Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Bob Camp]

Hi

At some very basic level, the GPSDO needs to decide when to go into or come
out of holdover. That decision often involves initial setup of the GPS module 
and
subsequent monitoring of the module. The risk in swapping modules is always
tripping over an obscure IF statement somewhere that does not work right with
the “new” module. On the Lucent boxes, there is a survey process “up front’ that
likely gets tangled when you change modules …..

Bob

> On Nov 15, 2017, at 1:27 AM, Mark Sims  wrote:
> 
> It might be eye candy, but is very useful eye candy when coupled with the 
> satellite SNR values.  A GPSDO does not NEED any communications to the GPS or 
> the outside world,  but EVERY commercial one does support it.  
> 
> The GPSDO firmware asks for the sat info from the GPS (so it can show it in 
> the SYST:STAT status page) and, if it doesn't get it, it assumes the GPS is 
> defective, crawls into a corner, and sobs.
> 
> 
> 
>> Isn’t info about what satellites are where, just eye candy and irrelevant to 
>> a real GPSDO?
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Bob Camp]

Hi

If you compare the PPS output of a simple GPS module (any of them) to a 
properly functioning GPSDO, you will see jumps in the module output. They
are a function of the way all of the modules quantize the PPS signal. For higher
resolution on the PPS you would have to use the sawtooth correction message
to somehow modify the PPS signal. 

Some GPSDO’s slip phase on the PPS as part of the alignment process so you 
can never say that there are only jumps in a bare module. GPSDO’s also steer
frequency to keep the PPS aligned. The damping (lag) in this process results in 
errors 
both in frequency and in the PPS edge. 

So, none of it is perfect (this is Time Nuts …). All of it has “issues” if you 
look 
close enough. A Frequency Nut would complain about some things and a 
Time (only) Nut wold complain about others. That’s not true in an absolute 
sense, but it is true in terms of what each would optimize for on a real world
device. 

Bob

> On Nov 14, 2017, at 12:55 PM, Jerry Hancock <je...@hanler.com> wrote:
> 
> Thomas, Yes, thank you, I read the work Dan posted.  
> 
> I have this TAPR GPS with the M12+ board in it that I received for free after 
> machining the end plates and the unused standby REF0 or REF1, can’t remember 
> which has the GPS in it.  I would like to have another 10Mhz standard in my 
> office.  I also have an OCXO out of my Tektronix 11301 I was given but that 
> uses a trimmer that I can’t really mod to discipline so that option of GPS + 
> OCXO is out.  So I wouldn’t mind figuring out a way to take the TAPR GPS and 
> feed it into the spare REF unit not unlike what the other REF unit is doing.  
> I would then have to fake some data per Dan’s site.  Having written this,  I 
> just might do this project now that I think about it. I could then also use 
> an STM32F7 board with display to post a clock as well.  I guess I would also 
> have to tap off the (debatably dirty) 10Mhz signal internally in the one that 
> is missing.
> 
> I’m going to go back and reread Dan’s paper.  There were questions about the 
> sawtooth IIRC and I remember seeing it when I compared the output of the TAPR 
> 1PPS vs the Lucent 1PPS as they would jump phase by successive increments and 
> then bounce back.  I don’t think we ever determined which one was moving but 
> I remember someone telling me it was most likely related to a sawtooth in the 
> discipline.  I don’t know enough about these things to say for sure, but 
> watching the 1PPS vs the other made me start to wonder about the absolute 
> phase accuracy of those signals.   You would have thought they would have 
> been perfectly in phase, no?  I go to bed at night with the confidence that 
> the free TAPR GPS is the culprit vs my Lucent that which cost me $200 when 
> all done.
> 
> So in summary, I have to plug the GPS REF unit, tap-off the 10Mhz someplace 
> on one or the other, feed the second REF unit with my TPAR GPS then also send 
> it some text (which is known by Dan) and I should get a second disciplined 
> 10Mhz unit.  This will take me a few weeks during which I will get bored and 
> forget why I was doing it in the first place.  So please remind me when I 
> post back.
> 
> Jerry
> 
> 
>> On Nov 14, 2017, at 8:50 AM, Thomas Petig <tho...@petig.eu> wrote:
>> 
>> Hi Jerry,
>> the 15 MHz is disabled by default, just bridging some pins enables the
>> output:
>> http://syncchannel.blogspot.se/2015/11/denuo-gps-hits-rev-b-dongles.html
>> 
>> If you want to insert some 1PPS signal to discipline it, you need some
>> fake some GPS messages. Dan has done some nice work here, a small ATTiny
>> is sufficient.
>> 
>> /Thomas, SA6CID
>> 
>> 
>> On Tue, Nov 14, 2017 at 08:30:54AM -0800, Jerry Hancock wrote:
>>> Bob, I thought you had to send it code, etc?  I have the two units
>>> with cable, etc running upstairs.  I want another one for in my office
>>> but the same guy only sells the REF0 and REF1 units separately now
>>> without the cable.  I thought about splitting the two and using this
>>> other GPS unit I have (it was one of the TAPR GPS Kits) to send the
>>> other one the 1pps.  You’re saying all you need is a plug?  I would
>>> need two functioning units.
>>> 
>>> Regards,
>>> 
>>> Jerry
>>> 
>>> 
>>> Jerry Hancock
>>> je...@hanler.com
>>> (415) 215-3779
>>> 
>>>> On Nov 14, 2017, at 8:13 AM, Bob Camp <kb...@n1k.org> wrote:
>>>> 
>>>> Hi
>>>> 
>>>> If you are going to get out the soldering iron, why simply make up a plug
>>>> to run the GPS unit stand alone?  Keep the second unit powered down 
>

Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Bob Camp]

Hi

Just going by memory (never a good thing ….); You can make the GPS unit believe 
that it has a “slave” present *and* that the slave is not working properly. 
It’s all done
with logic levels. In the “slave down” mode, the unit with the GPS puts out the 
15 MHz
and all the messages. The thing you loose is the (dirty) 10 MHz output from the 
slave.

Bob

> On Nov 14, 2017, at 11:30 AM, Jerry Hancock <je...@hanler.com> wrote:
> 
> Bob, I thought you had to send it code, etc?  I have the two units with 
> cable, etc running upstairs.  I want another one for in my office but the 
> same guy only sells the REF0 and REF1 units separately now without the cable. 
>  I thought about splitting the two and using this other GPS unit I have (it 
> was one of the TAPR GPS Kits) to send the other one the 1pps.  You’re saying 
> all you need is a plug?  I would need two functioning units.
> 
> Regards,
> 
> Jerry
> 
> 
> Jerry Hancock
> je...@hanler.com
> (415) 215-3779
> 
>> On Nov 14, 2017, at 8:13 AM, Bob Camp <kb...@n1k.org> wrote:
>> 
>> Hi
>> 
>> If you are going to get out the soldering iron, why simply make up a plug
>> to run the GPS unit stand alone?  Keep the second unit powered down 
>> as a set of spare parts….. Yes, it does depend a bit on what you are doing 
>> with them ….
>> 
>> Bob
>> 
>>> On Nov 13, 2017, at 11:50 PM, Jerry Hancock <je...@hanler.com> wrote:
>>> 
>>> Anyone have a spare cable for the Lucent setup?  I guess I can make one 
>>> with some DB15 connectors but trying to skip the effort.
>>> 
>>> Thanks
>>> 
>>> Jerry
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable

[Bob Camp]

Hi

If you are going to get out the soldering iron, why simply make up a plug
to run the GPS unit stand alone?  Keep the second unit powered down 
as a set of spare parts….. Yes, it does depend a bit on what you are doing 
with them ….

Bob

> On Nov 13, 2017, at 11:50 PM, Jerry Hancock  wrote:
> 
> Anyone have a spare cable for the Lucent setup?  I guess I can make one with 
> some DB15 connectors but trying to skip the effort.
> 
> Thanks
> 
> Jerry
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Bob Camp]

Hi

If the device pulls > 50 ppm at 80 MHz, it’s a wide range VCXO with a heater
on it :)  That is way more than you can pull a proper (low ADEV) OCXO.

Bob

> On Nov 13, 2017, at 5:04 AM, Mark Goldberg  wrote:
> 
> On Sun, Nov 12, 2017 at 7:02 PM, Mark Goldberg 
> wrote:
> 
>> 
>> On Sun, Nov 12, 2017 at 6:38 PM, John Miles  wrote:
>> 
>>> 
>>> Most of the 100 and 200 MHz bricks I've seen work with either 5 or 10 MHz
>>> .  I don't know if I've seen any 80 MHz units that do.  All of the ones
>>> I've bought on eBay have been from the customer-proprietary 500- series
>>> with unusual input frequencies.
>>> 
>>> 
>> I swept the input from 1 to 100 MHz. They lock at 38.4 MHz in. Yes they
>> are 4-5 kHz off when free running. Locked they are right on frequency.
>> 
>> Mark
>> 
>> 
> I have one more question.  Does anyone know if when unlocked it is possible
> to apply a tuning voltage to the Phase Lock Voltage monitor pin? What good
> is it to have an OCXO that needs to lock to a external frequency and is 4
> kHz off when unlocked? When locked, it comes up on frequency from first
> power on, so why would an oven be needed at all?
> 
> If interested, take a look at my qrz.com page for links as to why I am
> doing this. I have fallen down the rabbit hole of more accurate frequency!
> 
> Thanks,
> 
> Mark
> W7MLG
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS III

[Bob Camp]

Hi

There are papers from ION and other places detailing testing on the 
new(er) clocks. They do have quite good ADEV performance. If they 
start showing up on eBay, expect a bidding war ….

The most useful thing for an L1 user is getting the added bits into the
datastream for the epoch. That (plus ground firmware changes) will 
get rid of our roll over issues. Not much help for older product though. 

Bob

> On Nov 12, 2017, at 11:35 PM, Don  wrote:
> 
> 
> I read where the first GPS III satellite had finally been approved for
> flight. 
> 
> 
> The report said they will provide three times better location accuracy
> than current GPS.
> 
> Will  "better" onboard clocks help contribute to this improvement?  How
> are they "better"?
> 
> Can we expect enhanced timing accuracy from the timing receivers we use
> in our homemade GPSDO's?.
> 
> -Don
>  N5CID
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Bob Camp]

Hi

If it is a OCVCXO and it pulls > 50 ppm at 80 MHz, it’s got terrible phase 
noise close in.
That’s true with or without the PLL engaged.

Bob


> On Nov 12, 2017, at 7:46 PM, Mark Goldberg <marklgoldb...@gmail.com> wrote:
> 
> Yes, exactly those. With no input, would they be expected to be 4 kHz off?
> The spec for the standard part wants the input to be within 1e-7. I would
> not expect them to be so far off free running.
> 
> I saw 13 MHz on the 500-14273 and stayed away from those.
> 
> Do you know of any part numbers that use 10 MHz in? Wenzel would not tell
> me the exact specs of the 500 series parts available on ebay and only sent
> me the specs for the standard 501-14057 that takes 10 MHz.
> 
> I have a couple 8642As and can generate any frequency I want with decent
> phase noise, locked to my 10 MHz reference. I could try these frequencies
> above.
> 
> Do you know what the pll lock output does when the input frequency is off?
> These toggle high for any frequencies I have put in.
> 
> Any other ideas are appreciated.
> 
> Thanks,
> 
> Mark
> 
> 
> On Sun, Nov 12, 2017 at 5:19 PM, John Miles <j...@miles.io> wrote:
> 
>> Sounds like he's talking about the small 'bricks' that Wenzel sells with
>> internal PLL-disciplined OCXOs.  Some of these expect oddball input
>> frequencies.  Just looking at the 80 MHz parts on the shelf around here,
>> 500-14273 wants a 13 MHz input, 500-25010 uses 24.576 MHz, and 500-25009
>> uses 19.2 MHz.   So that's probably the issue, if two of them seem to be
>> failing the same way.
>> 
>> -- john, KE5FX
>> Miles Design LLC
>> 
>> 
>>> -Original Message-
>>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob
>>> Camp
>>> Sent: Sunday, November 12, 2017 2:03 PM
>>> To: Discussion of precise time and frequency measurement
>>> Subject: Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency
>>> 
>>> Hi
>>> 
>>> I guess my point was more that there is not a VCO / PLL combo in an OCXO.
>>> 
>>> If dropping the supply gets you on frequency, then you have moved things
>> a
>>> lot
>>> with that voltage change. 50 PPM is a lot of delta T on any normal OCXO
>>> crystal.
>>> That strongly suggests there is something wrong in the control circuit.
>>> 
>>> Bob
>>> 
>>>> On Nov 12, 2017, at 2:52 PM, Mark Goldberg <marklgoldb...@gmail.com>
>>> wrote:
>>>> 
>>>> The standard oscillator, 501-14057 (
>>>> www.wenzel.com/wp-content/parts/501-14057.pdf) will lock to an
>>> external 10
>>>> MHz reference and this one is marked "80 MHz" and "15V on the label.
>>> Maybe
>>>> someone swapped the labels. I did try lowering the supply voltage. It
>> got
>>>> to 80 MHz at about 11V and still did not lock to the reference. This
>>>> oscillator is specified at 1e-6/year aging. That is way less than it
>> is off
>>>> now.
>>>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Bob Camp]

Hi

I guess my point was more that there is not a VCO / PLL combo in an OCXO. 

If dropping the supply gets you on frequency, then you have moved things a lot
with that voltage change. 50 PPM is a lot of delta T on any normal OCXO 
crystal. 
That strongly suggests there is something wrong in the control circuit. 

Bob

> On Nov 12, 2017, at 2:52 PM, Mark Goldberg <marklgoldb...@gmail.com> wrote:
> 
> The standard oscillator, 501-14057 (
> www.wenzel.com/wp-content/parts/501-14057.pdf) will lock to an external 10
> MHz reference and this one is marked "80 MHz" and "15V on the label. Maybe
> someone swapped the labels. I did try lowering the supply voltage. It got
> to 80 MHz at about 11V and still did not lock to the reference. This
> oscillator is specified at 1e-6/year aging. That is way less than it is off
> now.
> 
> Mark
> 
> On Sun, Nov 12, 2017 at 12:34 PM, Bob Camp <kb...@n1k.org> wrote:
> 
>> Hi
>> 
>> It’s pretty certain that there is no PLL inside an 80 MHz low phase noise
>> OCXO.
>> If it is 4 KHz off frequency at 80 MHz, that gets you into the 50 ppm
>> range. Either
>> it is running on a really odd crystal spur or it’s not at the right
>> temperature. Drifting
>> around by 100’s of Hz ( = ppm’s at 80 MHz) is also a good indication that
>> the oven
>> is not doing it’s job correctly.
>> 
>> If multiple units do the same thing, either they all got busted being
>> puled from gear
>> (unfortunately that’s common) or you are running it at the wrong supply
>> voltage.
>> 
>> Bob
>> 
>> 
>> 
>>> On Nov 12, 2017, at 1:19 PM, Mark Goldberg <marklgoldb...@gmail.com>
>> wrote:
>>> 
>>> The seller has replaced it with one that does the exact same thing, which
>>> is weird to have two fail in the same way. They are getting hot and the
>>> frequency varies with the input voltage, so I tended to guess not the
>>> heater as I don't think it could pull that far over temp, and it always
>> is
>>> high. If it has an unlocked PLL on the output, with no control, would it
>> go
>>> to the max frequency? Since the seller seems to be reasonable, I was
>> trying
>>> to figure out best not to waste both of our's time, and me get a good
>> unit
>>> and them getting a sale.
>>> 
>>> Mark
>>> 
>>> 
>>> On Sun, Nov 12, 2017 at 9:22 AM, Bob Camp <kb...@n1k.org> wrote:
>>> 
>>>> Hi
>>>> 
>>>> As a guess - the oven circuit has stopped working. Next step
>>>> would be to tear it open and trace out the schematic. After that
>>>> make reasonable guesses for any parts that are poorly labeled.
>>>> 
>>>> Much of what shows up on eBay has been through the ringer in
>>>> China. A high percentage the OCXO's I get on eBay show up with
>>>> issues as a result. There is no way to be sure this or that part was
>>>> ok before it came out of the gear it was in. It’s always a gamble.
>>>> 
>>>> Bob
>>>> 
>>>>> On Nov 12, 2017, at 10:41 AM, Mark Goldberg <marklgoldb...@gmail.com>
>>>> wrote:
>>>>> 
>>>>> I have obtained a couple 80 MHz Wenzel Oscillators P/N 500-16423A. They
>>>> are
>>>>> proprietary but similar to the VHF PLO and 501-14057 Oscillators. I
>> want
>>>> to
>>>>> use this to replace the internal oscillator in my Perseus SDR, for
>> better
>>>>> accuracy and maybe better phase noise. Both of these are way off in
>>>>> frequency, about 4-5 kHz high from the ideal 80 MHz, and drift around
>>>>> hundreds of Hz. I believe they are broken in some way. The PLL lock
>>>> signal
>>>>> toggles when I put an input into the 10 MHz reference, but the output
>>>>> frequency is not affected.
>>>>> 
>>>>> Wenzel has answered some of my questions, but can't get specific as
>> these
>>>>> are proprietary to a customer.
>>>>> 
>>>>> Any experts on these oscillators out there?
>>>>> 
>>>>> Thanks,
>>>>> 
>>>>> Mark
>>>>> ___
>>>>> time-nuts mailing list -- time-nuts@febo.com
>>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>>>> mailman/listinfo/time-nuts
>>>>> and follow the instructions there.
>>>> 
>>>> __

Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Bob Camp]

Hi

It’s pretty certain that there is no PLL inside an 80 MHz low phase noise OCXO. 
If it is 4 KHz off frequency at 80 MHz, that gets you into the 50 ppm range. 
Either 
it is running on a really odd crystal spur or it’s not at the right 
temperature. Drifting 
around by 100’s of Hz ( = ppm’s at 80 MHz) is also a good indication that the 
oven 
is not doing it’s job correctly. 

If multiple units do the same thing, either they all got busted being puled 
from gear 
(unfortunately that’s common) or you are running it at the wrong supply 
voltage. 

Bob



> On Nov 12, 2017, at 1:19 PM, Mark Goldberg <marklgoldb...@gmail.com> wrote:
> 
> The seller has replaced it with one that does the exact same thing, which
> is weird to have two fail in the same way. They are getting hot and the
> frequency varies with the input voltage, so I tended to guess not the
> heater as I don't think it could pull that far over temp, and it always is
> high. If it has an unlocked PLL on the output, with no control, would it go
> to the max frequency? Since the seller seems to be reasonable, I was trying
> to figure out best not to waste both of our's time, and me get a good unit
> and them getting a sale.
> 
> Mark
> 
> 
> On Sun, Nov 12, 2017 at 9:22 AM, Bob Camp <kb...@n1k.org> wrote:
> 
>> Hi
>> 
>> As a guess - the oven circuit has stopped working. Next step
>> would be to tear it open and trace out the schematic. After that
>> make reasonable guesses for any parts that are poorly labeled.
>> 
>> Much of what shows up on eBay has been through the ringer in
>> China. A high percentage the OCXO's I get on eBay show up with
>> issues as a result. There is no way to be sure this or that part was
>> ok before it came out of the gear it was in. It’s always a gamble.
>> 
>> Bob
>> 
>>> On Nov 12, 2017, at 10:41 AM, Mark Goldberg <marklgoldb...@gmail.com>
>> wrote:
>>> 
>>> I have obtained a couple 80 MHz Wenzel Oscillators P/N 500-16423A. They
>> are
>>> proprietary but similar to the VHF PLO and 501-14057 Oscillators. I want
>> to
>>> use this to replace the internal oscillator in my Perseus SDR, for better
>>> accuracy and maybe better phase noise. Both of these are way off in
>>> frequency, about 4-5 kHz high from the ideal 80 MHz, and drift around
>>> hundreds of Hz. I believe they are broken in some way. The PLL lock
>> signal
>>> toggles when I put an input into the 10 MHz reference, but the output
>>> frequency is not affected.
>>> 
>>> Wenzel has answered some of my questions, but can't get specific as these
>>> are proprietary to a customer.
>>> 
>>> Any experts on these oscillators out there?
>>> 
>>> Thanks,
>>> 
>>> Mark
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Oscillators and Ovens

[Bob Camp]

Hi

I would say there are *very* few companies out there that will 
sell you high grade  precision OCXO crystals in single piece quantities.  
I think  you would get one much quicker and cheaper by pulling it out 
of an eBay OCXO. You can do good far removed phase noise with 
a lot of crystals. Once you look close in, the performance of the 
resonator matters. ADEV is the same issue, longer Tau’s are very
resonator dependent. 

Bob

> On Nov 12, 2017, at 10:14 AM, Attila Kinali  wrote:
> 
> Hi Jim,
> 
> On Wed, 1 Nov 2017 11:39:32 -0700
> jimlux  wrote:
> 
>> So, it would be nice to have a *cheap* lowish power packaged part that 
>> has the Q of an OCXO, but without the power consumption of the oven 
>> (typically measured in watts).
>> 
>> yeah, I'd be operating it *way* far from the optimum turnover temp, so 
>> the tempco might be huge (in oscillator terms), but I don't really care 
>> - in fact, that might give me a way to measure the temperature of the 
>> system.
> 
> Have you tried to build your own oscillator? There are a few companies
> that still sell single crystals. If you could piggy pack on some bigger
> customers production, you should be able to get the crystals relatively
> cheap. All you then have to do is to design an approriate, low noise
> oscillator. If you can relax your frequency specs, ie if you don't care
> if you are off by a few ppm, then you could scavenge the rejected crystals
> from said big customer.
> 
>   Attila Kinali
> 
> -- 
> You know, the very powerful and the very stupid have one thing in common.
> They don't alters their views to fit the facts, they alter the facts to
> fit the views, which can be uncomfortable if you happen to be one of the
> facts that needs altering.  -- The Doctor
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Wenzel VHF PLO Oscillators Off Frequency

[Bob Camp]

Hi

As a guess - the oven circuit has stopped working. Next step
would be to tear it open and trace out the schematic. After that
make reasonable guesses for any parts that are poorly labeled. 

Much of what shows up on eBay has been through the ringer in
China. A high percentage the OCXO's I get on eBay show up with 
issues as a result. There is no way to be sure this or that part was
ok before it came out of the gear it was in. It’s always a gamble.

Bob

> On Nov 12, 2017, at 10:41 AM, Mark Goldberg  wrote:
> 
> I have obtained a couple 80 MHz Wenzel Oscillators P/N 500-16423A. They are
> proprietary but similar to the VHF PLO and 501-14057 Oscillators. I want to
> use this to replace the internal oscillator in my Perseus SDR, for better
> accuracy and maybe better phase noise. Both of these are way off in
> frequency, about 4-5 kHz high from the ideal 80 MHz, and drift around
> hundreds of Hz. I believe they are broken in some way. The PLL lock signal
> toggles when I put an input into the 10 MHz reference, but the output
> frequency is not affected.
> 
> Wenzel has answered some of my questions, but can't get specific as these
> are proprietary to a customer.
> 
> Any experts on these oscillators out there?
> 
> Thanks,
> 
> Mark
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Favorite counters (current production)?

[Bob Camp]

Hi

Don’t get me wrong here, I think the SR620 is a great counter. My concern is 
that the
design came out a *long* time ago in terms of solid state generations. If 
things work out
as they often do, some random part in there is going to go obsolete. What part 
and when,
I have no idea. HP has always suffered from this when they shut down their 
custom 
IC production on this or that. I don’t know of anything custom in the 620 so it 
is sort of
a race to the end ….. My concern is going to the boss a year from now and 
having to
explain that the super counter is now EOL ….

Bob

> On Nov 10, 2017, at 2:50 PM, Magnus Danielson <mag...@rubidium.dyndns.org> 
> wrote:
> 
> Hi,
> 
> I would say CNT-99/91 and SR-620.
> 
> Bob has a point about 53230, since the others is older, but on the other 
> hand, it is a bit of a gamble. There are many aspects that goes into the 
> longlivety of a product, such as access to components, but also strategy of 
> companies.
> 
> The CNT-90/91 an 53230 both have graphical presentation, which is very 
> beneficial. The SR-620 still have better performance even being older than 
> everything else.
> 
> Cheers,
> Magnus
> 
> On 11/10/2017 05:37 PM, Bob Camp wrote:
>> Hi
>> There is no perfect answer. I’d go with the 53230 simply because it *might* 
>> be supported
>> the longest.
>> Bob
>>> On Nov 10, 2017, at 11:17 AM, Scott Newell <newell+timen...@n5tnl.com> 
>>> wrote:
>>> 
>>> What current production freq counters do people like for general 
>>> time-nuttery these days? There's a chance I can get a decent counter for 
>>> work, so I'm looking for suggestions. Bonus points for fanless. Don't need 
>>> anything past 200 MHz or so. Prefer ethernet over USB or GPIB.
>>> 
>>> The SR620 looks to be pretty big and a little dated. The 53230A seems to 
>>> have better specs and screen than the Tek/Fluke FCA3k series. Am I missing 
>>> any?
>>> 
>>> Rank your preferences!
>>> 
>>> -- 
>>> newell  N5TNL
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Favorite counters (current production)?

[Bob Camp]

Hi

There is no perfect answer. I’d go with the 53230 simply because it *might* be 
supported 
the longest. 

Bob

> On Nov 10, 2017, at 11:17 AM, Scott Newell  wrote:
> 
> What current production freq counters do people like for general time-nuttery 
> these days? There's a chance I can get a decent counter for work, so I'm 
> looking for suggestions. Bonus points for fanless. Don't need anything past 
> 200 MHz or so. Prefer ethernet over USB or GPIB.
> 
> The SR620 looks to be pretty big and a little dated. The 53230A seems to have 
> better specs and screen than the Tek/Fluke FCA3k series. Am I missing any?
> 
> Rank your preferences!
> 
> -- 
> newell  N5TNL
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Continously drifting HP 10811...

[Bob Camp]

Hi

One interesting thing to look at on modern OCXO’s:

Part of the factory alignment *probably* was intended to set the unit
at the center of the EFC range. Back in the days of people selecting caps 
or selecting resistors, that could be a pretty coarse kind of thing. At some 
point computers got into the act and OCXO’s got set very close to the 
center point. 

If you look at just about any of the OCXO’s that show up in GPSDO’s, they
are very close to mid range on the EFC. They may be ten or twenty years old.
They are mostly still on center. If you do the math on a 20 year old OCXO 
that is still < 0.1 ppm from center, that’s a crazy low drift rate.

No, not all OCXO’s are perfect after 20 years. There are a lot of examples that
have no output or have crushed cases. The stuff I’m talking about here are 
units that still are on the original card or something like that. Stuff that was
taken off a board with an axe …. not so much performance wise…..

Bob

> On Nov 9, 2017, at 12:59 PM, Mark Sims  wrote:
> 
> I put a UCT8663 DOCXO in my HP-53132A counter (using Gerry Sweeny's adapter 
> board).   I bought a bunch of those DOCXOs around 10 years ago.  It was never 
> powered up during that time.   Here are the notes that I made:
> 
> 
> UTC 8663 mounted on Sweeny DOCXO card in a HP 53132A counter.  The 8663 had
> not been powered up for over 10 years.  Below is the frequency drift per day
> as the 8663 aged in.  THe 8663 is spec'd at 1E-10 (1 mHz) per day aging. From
> past experience, they are capable of much better than that (1E-11 to 1E-12 per
> day).  They seem to be limited in the HP-53132A application by the EFC DAC / 
> VREF 
> performance.
> 
> The 8663 was mounted on the Gerry Sweeny aftermarket OCXO board for the 531xx
> counters.  For the first 30 days, the board was configured for the 0 .. 10V
> EFC DAC range.  The Sweeny board powers the DAC with +/- 12V which is a bit 
> out of the spec'd minimum +/- 13.5V required for optimum performance on 
> the 0 .. 10V range.
> 
> The Sweeny OCXO board is based up on the HP design with a couple of nice mods.
> First it has footprints for several common OCXO modules.  Second, it allows
> the DAC range to be configured for 0 .. 5V,  0 .. 10V, and +/- 5V.  
> 
> The circuit feeds the OCXO output through a differential line driver.  The 
> line
> driver sends the OCXO to the HP counter mother board through a ribbon cable.
> The motherboard makes the OCXO output available on a BNC on the counter
> back panel.  Checking the ADEVs of the raw OCXO outout and the counter output
> shows that the 53132A degrades the DOCXO output by around 1.5E-12 (raw DOCXO
> value around 5.1E-12 at 200 seconds,  counter 10 MHz output BNC around
> 6.5E-12)
> 
> For the first 30 days the EFC DAC reading was recorded and the HP53132A was 
> then auto-cal'd and the new EFC DAC output was recorded.  (The DAC readings
> for the first 10 days were lost when a momentary power failue occured and the
> system was not shut down cleanly).
> 
> The initial 30 day run was done with the Sweeny board DAC configured 
> for the 0 .. 10V range.  Given the DOCXO EFC sensitivity (around 0.75 V / Hz)
> and the 12-bit DAC, the minimum auto-cal resolution is 0.002 Hz.  Several
> auto-cal cycles were performed each morning until one was within 0.001 Hz.
> 
> DAC readings were made by a Tektronix DMM914 4.5 digit DMM, not the best tool
> for the task, but it was available.   The frequency reference for the tests 
> was an
> HP-5071A cesium beam unit. A TAPR TICC was used to measure the frequency of 
> the
> DOCXO.
> 
> 
>drift (Hz/day)DAC (after cal -> 24 hrs later)
> day 1:.298000 Hz   
> day 2:.057000 Hz   
> day 3:.033000 Hz   
> day 4:.022000 Hz   
> day 5:.017000 Hz   
> day 6:.011800 Hz   
> day 7:.009640 Hz  4.471V
> day 8:.008400 Hz  4.458V
> day 9:.006380 Hz  4.451V
> day 10:   .003880 Hz  4.443V
> day 11:   .002840 Hz  4.446V -> 4.438V  // power glitch caused reset
> day 12:   .003470 Hz  4.437V -> 4.437V
> day 13:   .002100 Hz  4.432V -> 4.433V
> day 14:   .001590 Hz  4.430V -> 4.430V
> day 15:   .001380 Hz  4.426V -> 4.428V
> day 16:   .001660 Hz  4.424V -> 4.426V
> day 17:   .000526 Hz  4.422V -> 4.423V
> day 19:   .000284 Hz  4.421V -> 4.423V
> day 20:   .38 Hz  4.423V -> 4.424V
> day 21:   .001019 Hz  4.420V -> 4.420V
> day 22:   .001350 Hz  4.417V -> 4.418V
> day 23:   .000402 Hz  4.417V -> 4.417V
> day 24:   .000953 Hz  4.418V -> 4.419V
> day 25:   .000304 Hz  4.417V -> 4.416V
> day 26:  -.000441 Hz  4.417V -> 4.418V
> day 27:   .000214 Hz  4.415V -> 4.415V
> day 28:   .000517 Hz  4.415V -> 4.416V
> day 29:  -.000998 Hz  4.415V -> 4.415V
> day 30:   .001300 Hz  4.415V -> 4.414V
> day 31:   .000423 Hz
> 
> 
> Powered down, replaced 53132A fan, changed DAC range to 0 .. 5V, and 
> the 53132A was put back into 

Re: [time-nuts] Continously drifting HP 10811...

[Bob Camp]

Hi

One of the weak points of a normal 10811 is that it is not hermetically sealed. 
Left 
in storage for years, they “soak up” humidity. In some cases it can take a 
fairly long
time (weeks, months) for them to fully dry out. Until they have been run for at 
least a
week, don’t get excited about the drift.

Bob

> On Nov 8, 2017, at 12:24 PM, Ulf Kylenfall via time-nuts  
> wrote:
> 
> 
> Gentlemen.
> I am about to try to repair a second 5065Aand have now tested a number of 
> 10811 Quartzoscillators that was in the junk box.
> In order to test the 10811, I put them it in a chassisthat is used for 
> GPS-locking. Adjust for lockand then monitor the EFC-voltage over time.
> Starting out with a lock condition and the EFCvoltage adjusted to -2.500V I 
> can see that theoscillators exhibit a monotonus EFC voltagedrift towards 0 
> volts. About + 1 mV in 3 minutes.
> By comparison, I have a 10811-60109that was tested in the same 
> GPS-application andthis unit is rock-steadyand that does not show any sign of 
> EFC drift.
> Test time has been 3 Days, and I beleive thata 10811 should have been able to 
> reachthermal equilibrium during this time.
> I can and will (of course) take them apart.Anything special to look for other 
> thanthe usual signs of long-term over-heated discretes?
> Ulf Kylenfall -  SM6GXV 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?

[Bob Camp]

Hi

If you go back into the NIST evaluations of various receiver modules ….. they 
don’t always
work best with the correct coordinates. Some have guessed there are residual 
math errors
in the devices. Others suggest the “radio side” may be at fault.  Indeed 
varying susceptibility 
to multipath *might* be the answer.

Bob

> On Nov 7, 2017, at 2:12 PM, Ole Petter Ronningen  
> wrote:
> 
> Yes, I thought so too - but on the same antenna I have a couple of L1/L2
> continously logging survey receivers; the position accuracy should be
> within 5-10 mm. Unless I've messed something up with coordinate systems,
> the position the UBlox thinks it has should be pretty good.
> 
> Ole
> 
> On Tue, Nov 7, 2017 at 5:43 PM, Jean-Louis Oneto  wrote:
> 
>> Hi Ole,
>> I think that the long term undulation are caused by a (small) error in
>> geodetic position of the antenna. The period should be a sidereal day
>> (23:56...)
>> Have a good day,
>> Jean-Louis
>> 
>> 
>> 
>> Envoyé depuis mon appareil mobile Samsung.
>> 
>>  Message d'origine 
>> De : Ole Petter Ronningen 
>> Date :07/11/2017  15:15  (GMT+01:00)
>> A : Discussion of precise time and frequency measurement <
>> time-nuts@febo.com>
>> Objet : Re: [time-nuts] ublox NEO-M8T improved by insulated chamber?
>> 
>> Hi all
>> 
>> Attached is a 24 hour plot of PPS out from a UBlox 6T against a hydrogen
>> maser. From 00:00 the bare receiver board was inside a polystyrene box
>> where it has soaked for many months, at 16:00 I removed the box exposing
>> the board to the airflow in the room, including AC. The box was left off
>> for the rest of the day.
>> 
>> The green trace is temperature in the lab. The "long term undulation" in
>> phase is normal, although I do not know the precise cause (multipath or
>> something else. I am reasonably sure it is not related to temperature in
>> the lab.
>> 
>> [image: Inline image 1])
>> 
>> Ole
>> 
>> On Sat, Nov 4, 2017 at 6:06 PM, Denny Page  wrote:
>> 
>>> [I hate finding unsent email in my folder :-]
>>> 
>>> Others may disagree, but I doubt that the type of small temperature
>>> variation you are referring to has any meaningful effect on tracking.
>> While
>>> the datasheet for the M8T says that there can be "significant impact" to
>>> the specifications at “extreme operating temperatures,” it gives the
>>> operating temperature as -40 to +85 C. Simply said, if you can stand to
>> be
>>> in the same room/space with it, I think you are fine.
>>> 
>>> Of much greater interest would be the antenna and it’s placement. I’m
>>> afraid I can’t specifically recommend a “good” antenna, but perhaps
>> others
>>> on the list can. For my EVK-M8T, I’m using the antenna that came with the
>>> kit and it works very well. I haven’t tested other antennas with the M8T
>> at
>>> this time, but I do have a number of other devices with antennas that
>> work
>>> well. I also have a few antennas that work poorly with all the devices,
>>> including the ones with which they came. Unfortunately pretty much all of
>>> them lack sufficient identification markings to identify
>> manufacture/model
>>> info.
>>> 
>>> Regarding placement, I’ve found that in a restricted area even a few
>>> inches can have a significant impact on the average number of satellites
>>> and signal level. In my case, it’s associated with the single building
>>> structure, but it sounds your case is even more restrictive. Although it
>>> can be a very lengthy process, performing antenna surveys may help
>> improve
>>> your situation. For each location, you need to monitor the number of
>>> satellites and signal level for 24 hours or more before determining the
>>> relative merit of that location. Repeat… and repeat.. and repeat.
>>> Determining the very best location for the antenna will likely require as
>>> many antenna surveys as you have patience for. :)
>>> 
>>> Hope this helps.
>>> 
>>> Denny
>>> 
>>> 
 On Nov 02, 2017, at 18:54, MLewis  wrote:
 
 Earlier this week, I put the breakout board with my NEO-M8T into an
>>> aluminum can. The can is split into a lower half and an upper half. The
>>> lower half was insulated on its sides internally, but open to the upper
>>> half, which wasn't insulated. The lower area contains the NEO-M8T on its
>>> breakout board and its matching com breakout board.
 
 In the unusual skyview/RF environment described below:
 - LH was typically showing two or three green sats, with a min of none
>>> and a max of five for very brief periods.
 - The average dBc of the green sats was 22 dBc, with a max of 29 dBc.
 - Two screen shots of LH from this time period show an Accu of 12 ns
>> and
>>> 33 ns.
 
 This morning, I insulated the inside of the upper half of the can, and
>>> added insulation to seal the top of the lower area into a chamber that
>>> contained the GPS module board & its com 

Re: [time-nuts] TAPR TICC boxed

[Bob Camp]

Hi

You could simply immerse all the cables in a swimming pool full of mercury … :)
(bonus points for a link to the prior discussion of that topic ..).

Bob

> On Apr 2, 2017, at 11:05 PM, Bruce Griffiths  
> wrote:
> 
> For even more fun you could try to detect the PTFE phase change  at around 
> 20C using a cable with PTFE dielectric.
> 
> A pulse source with somewhat more pulse to pulse jitter may be more useful in 
> that averaging will occur over a wider range of fine interpolator codes.
> 
> Bruce
> 
>> 
>>On 03 April 2017 at 05:34 Mark Sims  wrote:
>> 
>>I implemented the channel offset compensation feature specifically to 
>> make measuring cable delays more accurate. I wanted to measure my TDR 
>> calibration cable and another very precision delay line. I used Heather to 
>> null out the channel/connector delays and then replaced one of the "T" 
>> cables with the TDR cable.
>> 
>>My test setup / TICC was coming up with a -306 ps channel offset error. 
>> The test signal was the 1PPS output of a FTS4060 cesium. Connecting / 
>> reconnecting one of the test setup cables and re-doing the offset test (I 
>> was averaging for 1800 seconds) could produce compensation values that 
>> varied from -300 ps to -325 ps. Just de-doing the offset test without 
>> messing with the cables produced values around -300 to -310 ps.
>> 
>>BNC connectors aren't the best for precision timing. I need to re-run the 
>> test with SMA cables / T adapter and the precision HP connector torque 
>> wrench and see what that looks like. It would also be fun to lay a coax 
>> outdoors and see how the delay changes over a day as it heats/cools.
>> 
>>
>> 
 
>>>Some “cables” have very long delay numbers.
>>> 
>>>___
>>>time-nuts mailing list -- time-nuts@febo.com
>>>To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>>and follow the instructions there.
>>> 
 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS first LO need to be locked?

[Bob Camp]

Hi


> On Apr 1, 2017, at 11:18 AM, paul swed  wrote:
> 
> Thanks everyone but I am working on an austron 2201a so all the discussions
> on modern methods won't help. Whats is interesting is indeed the 2201 down
> converts to 80KHz and the does sample in an IQ fashion. Its all discreet
> chips and such.

If you have a free running VCO in the head end, then indeed you need to lock it 
to 
something. An unlocked VCO will not be close enough to frequency to do you any 
good.
The 8660 may or may not be close enough in free run mode. It depends a lot on 
what standard you have in yours. 


> Easily traceable and logical.
> I think I have what I asked for and am experimenting with active mixers and
> IFs made of minicircuit gain stages.
> I am using a commercial antenna with 34 db of gain. It says 50db I question
> that.

That is a very normal antenna gain spec and it was quite common in the era the
device you have was designed. I run a number of GPS gizmos that need a 50
db antenna on them. They *might* work with a 40 db setup. They do not work 
with something in the 20 to 30 db range. If you watch for a while (as in 6 to 
12 
months) you can indeed get good old 50 db gain antennas on eBay pretty cheap.

Bob

> But lots of gain to a HP IAM 81008 active mixer low drive LO. Then a 40db
> at least 75 MHz IF. (Pretty sure this is overkill.)
> The LO is a HP 8660c for now. Locked to a TBolt.
> Thats the reason for the question. I can shift the 8660 to the ausytron 10
> MHz.
> Regards
> Paul.
> WB8TSL
> 
> On Fri, Mar 31, 2017 at 7:47 PM, Bob kb8tq  wrote:
> 
>> Hi
>> 
>> 
>> There are a lot of GPS chips that do an I/Q mix down to a low IF. It’s
>> then (re) sampled from there. The “LO” in this case would down convert to
>> the low IF ….
>> 
>> Bob
>> 
>>> On Mar 31, 2017, at 6:08 PM, Magnus Danielson <
>> mag...@rubidium.dyndns.org> wrote:
>>> 
>>> God natt Attila,
>>> 
>>> On 03/31/2017 11:29 PM, Attila Kinali wrote:
 God kväll Magnus,
 
 On Fri, 31 Mar 2017 21:19:00 +0200
 Magnus Danielson  wrote:
 
> Still fills the function of LO, as the sample and hold operates as a
> mixer and the fold-down can be seen as an overtone mix followed by a
> sampling of the mix product, so well, it's about the same thing.
 
 "Harmonic mixer" is the word you are looking for :-)
>>> 
>>> Not necessarily. It could be a locked oscillator too.
>>> Harmonic mixer is another way to go.
>>> 
>>> Cheers,
>>> Magnus
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TAPR TICC boxed

[Bob Camp]

Hi

The whole delay difference thing does get into a “do you care?” sort of 
category. The 
testing process you are doing may well calibrate out (or ignore) an offset of 
this nature. 
This is quite true in a number of TimeNut sort of tests. 

Bob

> On Apr 1, 2017, at 4:02 AM, Bruce Griffiths  
> wrote:
> 
> The common mode propagation delay dispersion is also likely to be significant 
> unless one uses an SiGe ECL/CML comparator.
> 
> Calibrating this or actually the differential dispersion between channels is 
> an interesting but not insoluble issue.
> 
> Bruce 
> 
>> 
>>On 01 April 2017 at 18:49 Scott Stobbe  wrote:
>> 
>>Also interesting the LTC6752 is rail-rail input. Any rail-rail input opamp
>>I've used ends up with an ugly bump in input offset voltage transitioning
>>from the nmos or npn diff pair to the pmos or nmos. I'm not sure how good
>>or bad a rail-rail comparator may behave when common-mode biased in that
>>region.
>> 
>>On Fri, Mar 31, 2017 at 11:22 PM Bruce Griffiths 
>> 
>>wrote:
>> 
 
>>>Attempting sub nanosecond timing with an actual 1Mohm source is an
>>>exercise in futility. There are very few cases where one would want 
>>> to
>>>attempt precision timing measurements with such a high impedance 
>>> source.
>>>The 1M pulldown on the TICC input is merely intended to maintain a 
>>> valid
>>>logic input should the user leave that input disconnected. In actual 
>>> use
>>>with PPS signals the source impedance is in most cases a few tens of 
>>> ohms.
>>>If one wishes to have a 1Mohm input impedance for use with AC coupled
>>>signals then a low noise FET input buffer preceding the comparator is
>>>required.
>>> 
>>>Protection diodes in this application not only need to have low 
>>> leakage,
>>>they also need to turn on and off fast enough to be useful.
>>> 
>>>The propagation delay dispersion (both vs common mode and vs 
>>> overdrive)
>>>also need to be considered along with the comparator jitter.
>>> 
>>>Bruce
>>> 
>>>and overdrive (both vs overdrive and vs input common modeOn 01 April 
>>> 2017
>>>at 15:34 Scott Stobbe  wrote:
>>> 
>>>Fwiw, for a precision comparator you'll probably want a bipolar 
>>> front end
>>>for a lower flicker corner and better offset stability over cmos. For
>>>high-speeds the diffpair is going to be biased fairly rich for 
>>> bandwidth.
>>>So you will more than likey have input bias currents of 100's of nA 
>>> to uA
>>>on your comparator. Which is not great with a 1 megohm source.
>>> 
>>>On Fri, Mar 31, 2017 at 9:08 PM Charles Steinmetz 
>>> 
>>>wrote:
>>> 
>>>Mark wrote:
>>> 
>>>I thought about using the clamp diodes as protection but was a bit
>>>worried about power supply noise leaking through the diodes and 
>>> adding some
>>>jitter to the input signals...
>>> 
>>>It is a definite worry even with a low-noise, 50 ohm input, and a
>>>potential disaster with a 1Mohm input. Common signal diodes (1N4148,
>>>1N914, 1N916, 1N4448, etc.) are specified for 5-10nA of reverse 
>>> current.
>>>Even a low-leakage signal diode (e.g., 1N3595) typically has several
>>>hundred pA of leakage. Note that the concern isn't just power supply
>>>noise -- the leakage current itself is quite noisy.
>>> 
>>>For low-picoamp diodes at a decent price, I use either (1) the B-C 
>>> diode
>>>of a small-signal BJT, or (2) the gate diode of a small-geometry 
>>> JFET.
>>>A 2N5550 makes a good high-voltage, low-leakage diode with leakage
>>>current of ~30pA. Small signal HF transistors like the MPSH10 and
>>>2N5179 (and their SMD and PN variants) are good for ~5pA, while the 
>>> gate
>>>diode of a PN4417A JFET (or SMD variant) has reverse leakage current 
>>> of
>>>~1pA (achieving this in practice requires a very clean board and good
>>>layout).
>>> 
>>>I posted some actual leakage test results to Didier's site, which 
>>> can be
>>>downloaded at
>>><
>>> 
>>>
>>> http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
>>>  
>>> http://www.ko4bb.com/getsimple/index.php?id=download=03_App_Notes_-_Proceedings/Reverse_leakage_of_diode-connected_BJTs_and_FETs_measurement_results.pdf
>>> 
>>>.
>>>This document shows the connections I used to obtain the data.
>>> 
>>>The TICC doesn't have the resolution for it to matter or justify a
>>>HP5370 or better quality front end. I'll probably go with a fast
>>>comparator to implement the 

Re: [time-nuts] more of a time distribution question

[Bob Camp]

Hi

The 8736 is a very nice part. I think some sort of group buy would be a good 
idea. 

Bob

Sent from my iPhone

> On Mar 31, 2017, at 12:14 PM, Bob Darlington  wrote:
> 
> I guess it's time for me to finish up that NTP cape for the BeagleBone.
> I'm using a Furuno GT-8736 ( http://www.furuno.com/en/
> products/gnss-module/GT-8736 )
> 
> I built up a prototype about two years ago but... got married very shortly
> after that and haven't played with it since.
> 
> Is there any interest in something like this?   As with past group buys, I
> never charge a penny of profit and sell at cost.   I want to say the brand
> new GT-8736 boards are $26 a pop (my cost) from the vendor.
> 
> Is there a better board from Furuno for timing applications?
> 
> -Bob
> N3XKB
> 
> On Fri, Mar 31, 2017 at 1:03 AM, David J Taylor <
> david-tay...@blueyonder.co.uk> wrote:
> 
>> From: Hal Murray
>> 
>> That should work.  I haven't found a GPS with PPS for the beaglebone.  What
>> level of accuracy do you want?  If you only need 100 ms or so, then a
>> normal
>> junk GPS (no PPS) on USB should work.
>> ==
>> 
>> This works with the BeagleBone:
>> 
>> https://www.adafruit.com/product/746
>> 
>> Cheers,
>> David
>> --
>> SatSignal Software - Quality software written to your requirements
>> Web: http://www.satsignal.eu
>> Email: david-tay...@blueyonder.co.uk
>> Twitter: @gm8arv
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] GPS first LO need to be locked?

[Bob Camp]

Hi

There is a limited tracking range for Doppler. You would need to stay inside 
that. 

Bob

Sent from my iPhone

> On Mar 30, 2017, at 9:46 AM, paul swed  wrote:
> 
> I am curious if the first local oscillator on a GPS receiver must actually
> be locked or coherent to the reference oscillator in the GPS receiver
> typically running at some 10 MHz approximately. Or as long as the first LO
> is quite stable it doesn't matter because the receiver can track the code.
> This is a question for very classic receivers like Austrons, Odetics etc.
> Discreet. Modern fully integrated receivers are not in question.
> Thank you for your insights.
> Regards
> Paul
> WB8TSL
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Sub 20 ps time detection

[Bob Camp]

Hi

One of the nasty issues doing something like this is the voltage tolerances. If 
you 
are after 0.02 ns on a 2 ns edge, that is at the 1% level. If you want a 10X 
margin
to take the voltages out of the picture, you are now at the 0.1% level. 

If you have 3.3V logic 0.1% is 3.3 mv. That is the sum of the voltage issues 
with the supply
on the detector side, the reference to your comparator, and the offset of the 
comparator. If 
you are in a dynamic environment, things like temperature stability may have to 
be 
factored into each of those budgets. You may also have ground offset issues to 
deal with. 

How much this matters is very much a “that depends” sort of thing. Not knowing 
much
about the system involved does make this a bit of a guessing game. Sorry if the
guess is not applicable to what you are doing. 

Bob


> On Mar 25, 2017, at 12:32 PM, Mohammad-Hadi Sohrabi  
> wrote:
> 
> Hello,
> I have been following the posts here for a while and learned alot. I
> thought I could get some help as well.
> I need to detect less than 20 ps between two incoming pulses from a
> detector. pulses are 5ns wide and the rise time and fall time is around 2ns
> each.
> I am planning to use a constant fraction discriminator, simply a fast
> comparator with less than 500 MHz bandwidth for zero crossing detection and
> providing a very sharp edge. Then this can be fed into a TDC such as GPX2
> or anything of this sort. I think these can be fairly easily implemented on
> FR4.
> Recently I stumbled upon LTC6957-4 logic converter from another discussion.
> Can anyone guide me if this can be used for producing a sharp edge from a
> pulse that I mentioned? Datasheet suggests 0.5 ns rise time is possible but
> I think this is for single tone sine wave and not a short pulse.
> 
> Bests,
> Mohammad
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

Back before GPS and similar systems, hauling Cs standards on commercial 
aircraft was
a bit more common than it is today. One of the critical tricks of the trade was 
knowing where
each power outlet was on a specific plane and how close it was to this or that 
seat. The next
trick was knowing how to talk the crew into letting you plug the gizmo in the 
seat next to yours
into that outlet. Sometimes the magic worked and other times you had to depend 
on your 
battery pack. Needless to say, getting through the over ocean travel process 
with a dead
standard was not good news. 

Bob

> On Mar 22, 2017, at 10:59 PM, Bob Bownes  wrote:
> 
> It's not getting one past the airport authorities that's the issue. It's 
> getting one that's powered up past them. ;)
> 
> Written from about 10,000'. :)
> 
>> On Mar 22, 2017, at 20:15, Tom Van Baak  wrote:
>> 
>> Chris Albertson wrote:
>>> Why drive up a mountain?
>> 
>> "Because it's there" ;-)  And because there's a paved road, and it's free, 
>> and there's a place to stay overnight, and the mountain doesn't move. Plus a 
>> car makes a good portable time lab; you can share the experience with family 
>> or students or visiting time nuts; and a number of technical reasons.
>> 
>> But most importantly: you can remain at altitude as long as you want -- in 
>> order to accumulate just enough nanoseconds of time dilation to meet your 
>> experiment's S/N goal -- without running into (or much worse, going beyond) 
>> the flicker floor of your clocks.
>> 
>> There are several different ways to measure time dilation with atomic 
>> clocks. Some notes here:
>> http://leapsecond.com/pages/atomic-tom/
>> 
>> 
>>> Take the clock with you inside the pressurized cabin of a commercial 
>>> airliner
>> 
>> Yes, and this has been done many times. The first (1971) and most famous of 
>> all traveling clock relativity experiments is:
>> https://en.wikipedia.org/wiki/Hafele%E2%80%93Keating_experiment
>> 
>> For vintage hp flying clock articles see:
>> https://www.febo.com/pipermail/time-nuts/2013-January/073743.html
>> 
>> Two modern examples are described here:
>> 
>> "Time flies"
>> http://www.npl.co.uk/news/time-flies
>> 
>> "Demonstrating Relativity by Flying Atomic Clocks"
>> http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf
>> 
>> /tvb
>> 
>> - Original Message - 
>> From: Chris Albertson 
>> To: Tom Van Baak ; Discussion of precise time and frequency measurement 
>> Sent: Tuesday, March 21, 2017 7:12 PM
>> Subject: Re: [time-nuts] Time Dilation tinkering
>> 
>> "flight" there is the word.Why drive up a mountain?   Take the clock 
>> with you inside the pressurized cabin of a commercial airliner next time you 
>> are on one of those 10 hour trans=pacific flights.   You be taller then any 
>> mountain and it is actually cheaper then a weather balloon. 
>> 
>> Can you get a Rb clock past the TSA x-ray machine.   Maybe if you ask first. 
>>  There must be a way to hand cary specialized equipment.
>> 
>> On Tue, Mar 21, 2017 at 7:03 PM, Tom Van Baak  wrote:
>> 
>> But attached is one of the first plots where I put a SA.32m in a home-brew 
>> vacuum chamber and pulled down to a few inches of Hg for a few hours to 
>> simulate the low pressure of a flight up to 50 or 90,000 ft. For a high 
>> altitude relativity experiment -- where you'd like your clock to remain 
>> stable to parts in e-13 and not accumulate too many stray ns -- it's not a 
>> good sign when your clock changes by 2e-11 (that's more than 1 ns per 
>> minute) just because of ambient pressure changes.
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

In this case, the vacuum might work against you. You change the pressure outside
the package and you get a flex. Flex translates to dimensional changes. That 
gives you
a frequency shift. People make absolute pressure sensors this way :) Rb’s are 
by no 
means the only frequency standard impacted by this effect. Precision OCXO’s 
have the
same issue.

If you had enough room inside the package, you could do a “can in a can” sort 
of approach. 
The outer vacuum sealed can flexes. The inner vacuum sealed can does not see 
anything. 
You don’t eliminate the sensitivity this way, you do attenuate it quite a bit 
with each layer. 
The question then becomes - is is worth the increase in size? Since the 
pressure sensitivity 
is well below many other environmental factors …. probably not.

Bob

> On Mar 22, 2017, at 1:04 AM, jimlux  wrote:
> 
> On 3/21/17 4:29 PM, Hal Murray wrote:
>> 
>> scmcgr...@gmail.com said:
>>> However CSAC not subject to barometric effects as Rb units are
>> 
>> Does anybody tried to measure CSAC vs pressure?
>> 
>> 
>> 
> The physics package in a CSAC is a vacuum, so it probably won't make much 
> difference.
> 
> But, as a practical matter, I have a system with a CSAC going through thermal 
> vacuum testing as I write this. We'll get some test data and we can compare 
> the frequency against GPS and a OCXO at room temp/pressure, and at various 
> temps in vacuum.
> 
> Remind me in 2 weeks, and I should have the data plotted.
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] PLL Digital Loop Filter

[Bob Camp]

Hi

Some quick hints:

1) You need a way to digitize the phase input with adequate resolution. If you 
have a 1 second period and want
1 ns, you need a way to digitize at a 1:1,000,000,000 sort of level. That’s in 
the 30 bit range so a simple ADC
isn’t going to do it alone. 

2) You need a way to digitize the control output. If you have a +/- 2 ppm EFC 
range and a 16 bit DAC you get
a LSB step around 4/65,000 = 6x10^-8. If you are after < 1x10^-9, 16 bits isn’t 
going to get you there all by it’s
self.

3) In the middle of the two, you have a loop gain, an integrator time constant, 
and a bit of phase shift. That plugs
into the standard equations to come up with a solution (along with the normal 
sensitivities that drive any PLL). 

Yes, there are a lot of weird issues to deal with, but conceptually there isn 
not  a lot to it.

Bob
 
> On Mar 21, 2017, at 7:25 PM, James Peroulas  wrote:
> 
> Thanks for the hints and references everyone. I'll dig in and possibly come
> back with some more questions.
> 
> BR,
> James
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] PLL Digital Loop Filter

[Bob Camp]

Hi

Slipped a factor of 1,000 on the DAC … sorry about that …

Bob

> On Mar 21, 2017, at 7:25 PM, James Peroulas  wrote:
> 
> Thanks for the hints and references everyone. I'll dig in and possibly come
> back with some more questions.
> 
> BR,
> James
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

Hi

Ummm … e …. it’s a gas cell standard. I’d bet there is a pressure effect.

Bob

> On Mar 21, 2017, at 7:01 PM, Scott McGrath  wrote:
> 
> Noted
> 
> However CSAC not subject to barometric effects as Rb units are
> 
> Content by Scott
> Typos by Siri
> 
>> On Mar 21, 2017, at 4:18 PM, jimlux  wrote:
>> 
>>> On 3/21/17 12:51 PM, Scott McGrath wrote:
>>> Or perhaps use the Symmetricom CSAC ...
>>> 
>>> Relatively expensive but might work
>>> 
>> 
>> 
>> The CSAC  is 8E-12 AVAR at 1000 seconds, comparable to a Rb.
>> 
>> 
>> See also http://tycho.usno.navy.mil/ptti/2011papers/Paper27.pdf
>> which shows a bit better performance (3E-12 @ 1000s), but the best 
>> performance appears to be at 10,000 seconds.
>> 
>> 
>> but don't you need better?
>> Attila wrote> You will need a stability 1e-14 @1d.
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

[Bob Camp]

HI


> On Mar 21, 2017, at 4:52 PM, Trent Piepho  wrote:
> 
> Thanks to all who responded.  Yes, I know PPS is the way get a more
> accurate timestamps.  That is the plan, but it takes more time to write
> FPGA programs.  The surprise is not that there is considerable jitter on
> the NMEA output, but rather why does the jitter have patterns in it?
> 
> It seems significant enough that someone who had used NMEA for time
> would have noticed it before.  Unless it is somehow unique to me, but
> how would that be?

The simple answer is that we *do* see it and that’s why we use PPS and not 
NMEA. 
Arrival times on NMEA sentences varying over a 100 ms region is not at 
all unusual. Getting them out “exactly on time” is not a priority compared to 
the
other tasks overworked CPU in the module needs to perform. 

Bob


> 
> On Tue, 2017-03-21 at 16:43 -0700, Kiwi Geoff wrote:
>> For example, here is a (24 hour) graph from my Garmin 18x (firmware
>> v3.6) where a plot (thanks to Hal) shows the start time of the NMEA
>> sentence from the time of the GPS 1PPS edge.
> 
> I've tried to duplicate that graph to some extent, plotting NMEA
> sentence offset from system clock.  Attached and also at
> https://goo.gl/photos/TBEg27SRqY2EQW3HA
> 
> In this plot I've taken the offset from the system clock, fitted it to a
> simple f(x)=a+b*x model, then plotted the residuals.  I.e., I've taken
> out a constant clock drift (of 5.7 ppm).  While interesting, there
> doesn't appear to be any pattern that synced to every four hours start
> at 00 UTC time.  It's not a lot different than your plot from the 18x.
> 
> However, if I plot not the raw offsets, but the mean and variance over
> an interval, we see there is a clear four hour pattern, and it's synced!
> 
> https://goo.gl/photos/JZhBbFKFzkBAykti6
> 
> Why would a GPS module produce jitter with a pattern like this?
> 
> 
> On Tue, 2017-03-20 at 15:19 -0700, Chris Albertson wrote:
>> If you have an FPGA available then you could significantly improve
>> system time keeping.   Currently the PPS interrupts the CPU to
>> snapshot internal counter.   Unpredictable interrupt latency lifts NTP
>> timekeeping to about 1 or 2 microseconds but is the counter snap
>> shooting could be moved out to FPGA hardware there would be no unknown
>> latency and you could get NTP to break a "magic" 1uS barrier.   I've
> 
> My initial idea for the PPS hardware would be to start a counter in the
> FPGA, there is a good 100 MHz clock for this, on the edge of the PPS
> signal.  The irq handler can use the value of the counter to subtract
> out most of the software interrupt latency.  Most, since the Linux PPS
> framework wants to create the system clock component of the PPS
> timestamp pair _after_ the hardware part is generated.  There is some
> delay and jitter in how long it takes the CPU to create the system
> timestamp after I have created the latency compensated PPS timestamp.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TS2100: Which OCXO's work?

[Bob Camp]

Hi
> On Mar 21, 2017, at 1:37 AM, Bruce Lane  wrote:
> 
> Fellow time-tickers,
> 
>   My thanks to Greg for getting back to me (and apologies for the spam
> filter bounce) but, apparently, MTI 240 OCXO's have become unobtanium.
> 
>   With this in mind: What other OCXO's are compatible with the
> Symmetricom TS2100? My understanding is whatever I choose would need a
> 12V oven circuit and a 0-5V tuning control input.

You also need the same pinout footprint. 

The problem with all the eBay OCXO’s is the suspect quality of the parts. About
the only way to get a good one is to buy a number of them and spend a bunch of
time testing them.

Bob

> 
>   Suggestions?
> 
>   Thanks much.
> 
> -- 
> ---
> Bruce Lane, ARS KC7GR
> http://www.bluefeathertech.com
> kyrrin (at) bluefeathertech dot com
> "Quando Omni Flunkus Moritati" (Red Green)
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Time Dilation tinkering

[Bob Camp]

H

> On Mar 21, 2017, at 4:58 AM, Tom Van Baak  wrote:
> 
> Hi Hugh,
> 
>> If I do the math correctly that's about 14ns difference per 24h the 
>> clocks are separated by that altitude. [1]
> 
> That's correct. For your 1500m elevation gain, the gravitational redshift, 
> the df/f frequency change, will be about 1.6e-13. To be able to measure with 
> any confidence you'll want your clocks to be stable to about 2e-14, at tau 1 
> or 2 days.
> 
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
> 
> There are tricks and technical factors, but the main one is how stable these 
> are at tau 1 day. Buy or borrow a few of them and see if they are mutually 
> stable to the level required. I suspect not. But perhaps other time nuts 
> could comment on how stable their surplus Rb are out to tau 1 day.
> 
> There are lots of other details; some to your advantage, some not. But if the 
> surplus Rb can't perform down in the -14's at a day, even in laboratory 
> conditions, then the rest of the discussion doesn't matter.

An ex-telecom Rb will run a bit below 1x10^-12, but not below 1x10^-13 at tau = 
1 day. Roughly speaking it’s about 10X less stable than you need. That’s in a 
carefully controlled temperature and pressure environment. One fake out with 
Rb’s is that they are pressure sensitive. You *will* see an impact simply from 
the lower pressure on the top of the mountain. How much impact varies from unit 
to unit. It’s a good bet you need to compensate for it well before you get to 
1x10^-13 on a mountain trip. 

To put this all in context, a 5071 in good condition can (barely) do this 
experiment by running up to a mountain top. There’s a lot of fiddly details you 
need to take care of even with a 5071.  AFIK, Tom is the first to do it this 
way (Cs in the back of the family car). All previous work with older Cs 
standards had to go to much greater lengths to observe the effect. If you take 
a standard up to satellite orbit sort of altitude, you get a shift of 
~1.5x10^-10. That would be fine for a number of frequency standards. It is not 
very practical on the transport side of the experiment. 

Many options, but none of them easy. 

Bob

> 
> Yes, the TAPR TICC counter would work well for this experiment. But to be 
> honest, any old nanosecond-level counter is good enough. I say this not to 
> discourage you from a good excuse to buy a TICC, but to encourage you to do 
> the ADEV math to see how clocks and counters and tau can interact in your 
> favor.
> 
> /tvb
> 
> - Original Message - 
> From: "Hugh Blemings" 
> To: "Discussion of precise time and frequency measurement" 
> 
> Sent: Monday, March 20, 2017 7:38 PM
> Subject: [time-nuts] Time Dilation tinkering
> 
> 
>> Hi,
>> 
>> I've been mostly lurking on the list for some time now and follow with 
>> interest the many discussions.  Very much at the early stages of my 
>> time-nut journey, but enjoying it so far :)
>> 
>> I'd like to have a go at re-creating the efforts of Tom (and I gather 
>> others) in taking a clock up a mountain for a while and seeing if I can 
>> measure the relativistic changes.
>> 
>> Being based in Australia gives me a couple of challenges, for one we 
>> don't really do mountains in the same sense as much of the rest of the 
>> world - so the highest peak I can readily get to from Melbourne is about 
>> 1,600m ASL.  I live at 80m ASL - so a delta of around 1,500m altitude 
>> and several hundred km drive.
>> 
>> If I do the math correctly that's about 14ns difference per 24h the 
>> clocks are separated by that altitude. [1]
>> 
>> We also lack quite the same surplus market here as the US, so purchasing 
>> a Caesium based standard is well beyond my means.
>> 
>> This got me to wondering if a Rubidium based standard might do the trick 
>> - the Efratom SLCR-101s seem readily available for ~USD$200 mark.
>> 
>> Clearly there'd need to be a bunch of extra gubbins [2] added to the 
>> 10MHz standard to turn it into an actual clock/counter including battery 
>> backup and so forth.  And would need a pair of everything.
>> 
>> Before I delve too far into the planning, I'd be interested in feedback 
>> as to whether this style of Rb standard is likely to be up to the task 
>> of being the core of such an endeavour or not ?
>> 
>> Oh I should add - my plan was to build the systems such that they 
>> function as nice standalone time/frequency references once this 
>> experiment is concluded :)
>> 
>> Thanks in advance,
>> 
>> Kind Regards/73,
>> Hugh
>> VK3YYZ/AD5RV
>> 
>> 
>> 
>> [1] gh/c^2 x 3600 x 24  Where h is 1500, g and c the usual values :)
>> 
>> [2] I presume at a minimum a counter running at a 5ns or less "tick" fed 
>> from a frequency source locked to the 10MHz of the Rb standard.  This 
>> counter would need to be latched for reading from an external signal 

Re: [time-nuts] time-nuts equipment verification from scratch (was: WTB: GPSDO)

[Bob Camp]

Hi


> On Mar 21, 2017, at 1:07 AM, Chris Albertson  
> wrote:
> 
> I built one of these using a PWM DAC also.   The design was posted to this
> list so I can't take credit for the idea.   But we used two PWM output
> pins.   The PWM provides more voltage range than is needed by the OXO's
> EFC.  To the output was scaled by a voltage divider.  This also scaled down
> thew step size. The second PWN output was scale down even more, like
> maybe 100X more.  The two PWM outputs were added.  One does course
> adjustment the other fine.   The software first sets the course PWM and
> then the fine one takes over.
> 
> But the PWM output was just run through an RC filter with a very long time
> constants low pass filter with corner freq. < 1 Hz.   The goal was to build
> a VERY low cost GPSDO and adding a good external DAC would add to the cost.
> 
> Someone here recently suggested that one could do as well by simply
> adjusting a good oversized crystal with a screw driver as they could using
> a simple GPSDO.   Well, before building the GPSDO I tried keeping my OXO in
> sync with my Tunderbolt using just a screw driver and a dual trace analog
> tektronix scope.  It is REALLY hard to do with a screw driver.

You need a finer adjust pot on the EFC. It’s no different than the process you 
describe above with the PWM’s. With a PPS that is good to 10 ns, you can get
to 0.1 ppb in 1000 seconds with margin. You will have a pretty good idea of 
what is going on in 100 seconds. 

If you are going to rig it up, a 20 turn wire wound pot with a dial on it is 
the high
end approach. Set up the pot with a ~1x10^-8 full scale range. You then have 
roughly 5x10^-10 per turn. The cool part is that you can log the readings and
work out what’s going on with the OCXO.

Bob

>   Some tines
> I'd think I had it right then I'd look at the scope after 30 minutes and
> fine one sine wave had gained 1/4 cycle on the other.  Lots of reason for
> this, perhaps one of my voltage regulators are temperature sensitive,
> "stiction" in the screw I was turning.  Who knows. But my simple GPSDO
> would notice the 1/4 cycle error and fix it automatically
> 
> It real life for practical purposes I use the Rb clock, was lucky to get
> one at the old $35 price.
> 
> On Mon, Mar 20, 2017 at 4:43 PM, Mark Sims  wrote:
> 
>> The "DAC" was PWM based, but used a separate voltage regulator for the
>> "reference".  I never tried it using the USB power as the reference.
>> 
>> The OCXO (+board) uses less than 500 mA warming up (which it does rather
>> quickly).  It's in a small hermetic package about twice the size of a
>> standard DIP-14 oscillator package.  There was a Ebay seller several years
>> ago offering them at $15 each or 10 for $100.
>> 
>> The Chinese "Arduino" board (it's not really and Arduino,  just a MEGA 328
>> and a proto area)  has a micro-USB connector for power input but does not
>> implement USB data.   I used the processor serial port with a level shifter
>> dongle.   The firmware was a cheap and dirty hack and I didn't implement
>> much in the way of control or monitoring... never got around to improving
>> it.  The project was basically "Hey, I forgot I had those parts...  Hmmm,
>> one could build a simple GPSDO... why not?
>> 
>> -
>> 
>>> Did you use the Arduino's PWM output plus a LPF for the DAC, or a
>> separate
>> DAC? If PWM, did you have problems with noise or sensitivity to the
>> USB-provided supply voltage?
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Four hour cycle in GPS NMEA jitter

[Bob Camp]

Hi


NMEA sentences are not the best thing to use for timing. If you *do* decide to 
use them, configure the 
receiver so that one and only one sentence comes out. Any time you have more 
than one, you run the risk
of collision in the serial buffer on the part. Next thing to do is to pick the 
shortest useful sentence you 
can find. In some cases you only have one option. 

Next up is to be sure that your PC is set up so that there is minimal lag in 
serial processing. That may not
be as simple as you might think. All modern OS’s head off to do “interesting 
things” from time to time. The
usual approach is to kill just about anything that *might* create an issue. 

Once you have all that, you start pruning the outliers and fitting to the 
center of the data. Since you don’t have
a super duper clock on your motherboard, you are fitting both the randomness of 
the clock and the GPS. The
answer is to go slow and look at data over a lot of samples. 

The other answer to all this is to use a GPS with a PPS out. Feed that into 
some sort of capture process and 
go from there. The result is likely to improve things by at least a couple 
orders of magnitude. 

Bob

> On Mar 20, 2017, at 5:00 PM, Trent Piepho  wrote:
> 
> Hello time nuts,
> 
> I'm working on a custom embedded Linux device, with a custom inertial 
> reference unit, which contains a GPS module.   The module is a Telit JN3, 
> which is based on the SiRFSTAR IV I believe.  I'd like to use the GPS to sync 
> the Linux system clock.  Eventually I'd like to use the PPS signal, which is 
> routed to a FPGA that's part of the CPU, to implement a custom PPS hardware 
> module that I can write a kernel driver for and use the Linux hardpps system. 
>   And maybe make that feedback to the CPU's main clock source, since the FPGA 
> also controls that and could create a PLL between the TCXO that serves as the 
> master clock signal and the CPU's source clock.
> 
> But first things first.  I'm just grabbing the time from NMEA sentences.  And 
> there's quite a bit of jitter there!  Clearly using the first sentence output 
> by the GPS is critical.  I've tried to account for any time delays in the 
> software.  I think it's the GPS module that is creating the largest source of 
> jitter.  It appears to go in four hour cycles, peaking at 0:00Z, 4:00Z, 
> 8:00Z, etc.
> 
> Does this sound like something that one would expect with the NMEA output of 
> a non-timing GPS?  Is it related to satellite orbits?  Or perhaps is has 
> something to do with the design of the SiRFStar IV?
> 
> I'll attach a graph of what I'm seeing.  If the attachment doesn't come 
> though it's viewable at https://goo.gl/photos/JtYfJCpRSZb3hCnM8.
> 
> Methodology for the graph:
> System clock is left free running and not disciplined, after an initial one 
> time set based on the GPS time.
> On each NMEA GGA sentence, sent at 1 Hz, the system clock's offset from the 
> NMEA timestamp is measured.
> Each minute, the mean, std.dev, min and max are found for the last 60 offset 
> samples.  This is plotted on the graph.
> Any outlier samples, defined as more than 3 sigma from the previous mean, are 
> also plotted.
> Concurrently, the chrony NTP daemon is running and monitoring the IT dept's 
> NTP server, but NOT being used to set the local system clock.
> Once a minute, the system clock's offset to chrony's idea of the NTP server's 
> clock is also measured.  Chrony is using an algorithm based on median 
> filtering to get its idea of the NTP server's clock.
> The NTP server is just a windows domain controller synced to the internet NTP 
> pool and far from a precision source.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WTB: GPSDO

[Bob Camp]

Hi

A good OCXO run continuously should get down to < 0.1 ppb / week. Doing a tweak 
every Saturday is likely enough to keep it in that range. The *big* advantage 
is that you
have the ADEV of the OCXO without any scruffy stuff from the control loop 
getting in the 
way. If your objective is to run something like a frequency counter, you 
probably are better
off with the trimmed OCXO.

Bob

> On Mar 20, 2017, at 5:26 PM, Mark Spencer <m...@alignedsolutions.com> wrote:
> 
> Hi:
> 
> Bob's comment about adjusting an oscillator from time to time aligns well 
> with my limited experience in the time nuts hobby.Once I realized that in 
> practice my better OCXO's were typically more than stable enough for my 
> intended uses things became much simpler.   I also realized that I could 
> utilize my collection of time interval counters to compare my chosen 
> reference to other references (including a GPSDO) while also comparing the 
> chosen reference to the "Device Under Test."  I realize this isn't likely an 
> approach that a commercial lab would use but for my hobby use it seems to 
> work ok for me.
> 
> I've more or less shelved my plans to discipline one of my high end OCXO's 
> via a home brew GPSDO scheme.
> 
> Mark Spencer
> 
> 
>> On Mar 14, 2017, at 5:24 PM, Bob Camp <kb...@n1k.org> wrote:
>> 
>> Hi
>> 
>> 
>>> On Mar 14, 2017, at 6:33 PM, Tim Lister <lister...@gmail.com> wrote:
>>> 
>>> On Fri, Mar 10, 2017 at 2:35 PM, Chris Albertson
>>> <albertson.ch...@gmail.com> wrote:
>>>> A GPSDO is not hard to make.  All you need is some way to compare the
>>>> phase of two signals, an XOR gate can do that.  Then a small $2
>>>> process moves the control voltage on the crystal.I tried one to
>>>> build the simplest GPSDO that could still work.   Got the parts count
>>>> down to about four or five and the cost well under $10 plus the OXO
>>>> which was about $20.  The simplest dumb one I could make keeps about
>>>> e-10.  Not great but enough for many uses.   I compared to my
>>>> Thunderbolt and I could see the phase advance and retreat.  Just a
>>>> little most sophistication and I likely could do much better but my
>>>> goal was to prove to myself that a GPSDO could be build VERY simply
>>>> with cheap parts
>>> 
>>> Hi Chris, that's good news that a GPSDO is that easy to make (at least
>>> a basic one) as that is exactly my medium term plan !
>> 
>> Actually it’s much easier. Just put a DVM on the XOR once a week and 
>> adjust your oscillator with a screwdriver. It saves *lots* of time and money.
>> 
>> Bob
>> 
>> 
>>> The issue of
>>> course is having something to test the newly built GPSDO against... I
>>> got one of the rehoused Trimble UCCM-based GPSDOs off ebay a while ago
>>> but haven't been super happy with it. It's quite a bit less sensitive
>>> than more modern GPS receivers and it often struggles to get even 1
>>> satellite with the indoor patch antenna. At one point both red alarm
>>> LEDs came on and stayed on despite power cycles - I eventually fixed
>>> that by taking it apart and finding and hitting a reset button on the
>>> board. Currently although I can talk to the unit over serial and it
>>> seems to respond, Lady Heather is not seeing any output from it.
>>> 
>>> Combined these things don't give me a great deal of confidence that
>>> this unit will act as a stable master reference. I was wondering if a
>>> second GPSDO like Russ linked to would work better (I have a ublox
>>> LEA-6T GPS already which I plan to use as the basis of the homebuilt
>>> GPSDO and it consistently sees many more satellites than the UCCM
>>> with a similar indoor antenna)  or put the money to getting an outdoor
>>> antenna mounted (don't feel happy drilling holes in the house myself)
>>> by someone. Do 2 GPSDOs tell you much more or just that each is
>>> different and you need a third to adjudicate ? (I can see a slippery
>>> slope looming from here...)
>>> 
>>> Cheers,
>>> Tim
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Optical Cesium or maybe Cesium "light"!

[Bob Camp]

Hi

Get a bigger bag :)

Bob

> On Mar 18, 2017, at 4:45 PM, Wojciech Owczarek  
> wrote:
> 
> I tried lifting it but it wouldn't fit in my bag :(
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Antique precision timing device without

[Bob Camp]

Hi



> On Mar 17, 2017, at 7:41 PM, Morris Odell  wrote:
> 
> HI all,
> 
> Thanks to all those who responded to my post and also for the great pics of
> other tuning forks. It's amazing that they were still being used for
> electronic purposes as recently as the 1960s.

Motorola was still very much in the business of making Vibrasenders and 
Vibrasponders
to generate and decode PL tones on FM radios well into the 1980’s. They were 
really not much more than tuning forks set to the proper tone frequency.

Bob


> Actually now that I think
> about it I have seen little tuning forks used to check the function of
> modern police speed radars so they still have some use. Musicians don't use
> them any more - guitar players will know the little electronic tuning
> devices clipped to the  neck of the instrument that displays the frequency
> or key of each string. Doctors still use 125 Hz forks to test vibration
> sense and higher frequency ones to test for conductive hearing loss. 
> 
> In answer to some of the questions posted: no there was no documentation
> with the unit. The most useful thing was the "12 volts in" label on the
> power socket so I knew where to start. The rest of it was necktop analysis.
> The fork is maintained by means of a central electromagnet and small leaf
> spring contacts on the tines - they also provide the 25 Hz power for the
> motor which runs at 12 volts. Of course they would reduce the Q of the fork
> a little and affect its resonance but I'm sure that was taken into  account
> by the designer and the frequency & symmetry can be adjusted with the
> weights on the ends. Operating current is about 0.5A at 12 volts when
> running and 1A when the fork is not vibrating. There's a switch marked "Neon
> Lamp" that controls the AC supply to a pair of clips between the tines of
> the fork. They are about 3-4 inches apart and I have no idea what sort of
> long thin tubular lamp would fit between them. Just for fun I'm going to
> make a simple stroboscope with a 555 timer and some high intensity white
> LEDs I have lying around to see if I can use it on the fork.
> 
> Cheers,
> 
> Morris
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Bob Camp]

Hi


> On Mar 16, 2017, at 9:43 PM, Hal Murray  wrote:
> 
> 
> kb...@n1k.org said:
>> Under normal conditions, the Gold Codes on CDMA are synchronized to < 100
>> ns.
> 
> Is that a full time synchronization, or something like a PPS where they can 
> get the ticks lined up but not know the time for any individual tick?

The GPSDO sends out a pp2s that is specified to be aligned to GPS time to 
within 
100 ns. The transmitter lines up to this “ever other second” pulse. There is 
normally
a serial link that tags the time. 

Bob 

> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vectron 233Y5317 OCXO data 250 Mhz

[Bob Camp]

Hi

Not an OCXO, but it’s a Vectron 233

https://www.vectron.com/products/xo/co-233_233h.htm

The 233’s are all un-compensated XO’s

Bob

> On Mar 16, 2017, at 4:51 PM, Jeff AC0C  wrote:
> 
> Looking for a datasheet for this OCXO, or for the general family.  
> 
> Thanks!
> 
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Smart Phone time display accuracy...?

[Bob Camp]

Hi

Under normal conditions, the Gold Codes on CDMA are synchronized to < 100 ns. 
It’s only when something goes wrong
that they drift out to the 10 us range. Once they get there, the transmitter 
needs to shut down. Unfortunately, there is no
mandatory connection between the transmitter time source for the output coding 
and the time reported to the phone. Yes,
that is really weird. 

Bob

> On Mar 16, 2017, at 1:06 PM, Mike Garvey  wrote:
> 
> CDMA mobile telephony needs system synchronization to +/- 10 uS in order to 
> smoothly handoff a moving client from one cell to the next. Most systems use 
> GPS to maintain this 10 uS.  This says nothing about how bad it could get 
> after that.
> Mike
> 
> -Original Message-
> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mike Baker
> Sent: Wednesday, March 15, 2017 22:33
> To: time-nuts@febo.com
> Subject: [time-nuts] Smart Phone time display accuracy...?
> 
> Hello, Time-nutters--
> 
> Any thoughts on what the likely accuracy of smart phone time
> displays might be?   I am thinking that the stacking of delays
> along the path to its receive antenna plus any internal processing delays 
> would accumulate to some unknown degree.  Any thoughts on this?
> 
> Mike Baker
> *
> ___
> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to 
> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

Ok, I missed that. 

Unless there is also a trimmer cap, the EFC will be >> 0.01Hz if it needs to be 
on frequency for any rational amount of time. If the crystals are the typical 
old fundamentals, 
they may age 5 to 10 ppm / year when heated to OCXO temperatures. That’s +/- 25 
to +/-
50 Hz just for the first year. 

Bob

> On Mar 15, 2017, at 6:11 PM, Bruce Griffiths <bruce.griffi...@xtra.co.nz> 
> wrote:
> 
> Bob
> 
> He stated 0.01Hz EFC tuning range was adequate.
> Gave no spec as to how close to nominal frequency is required though.
> 
> Bruce
>> On 16 March 2017 at 10:53 Bob Camp <kb...@n1k.org> wrote:
>> 
>> 
>> Hi
>> 
>> By most modern definitions, “high stability” starts around 1x10^-12 (1 ppt)  
>> at a tau of 1 second to 
>> 10 seconds. There are $20 eBay OCXO’s that run at that level.  With a 
>> fundamental crystal you 
>> aren’t going to get to that point. 
>> 
>> How much EFC range are you after? 
>> 
>> How good a CNC setup do you have?
>> 
>> What kind of temperature test setup do you have? 
>> 
>> Simply put, the design approach is a “test over temperature / collect data 
>> -> optimize” loop. 
>> Without good frequency vs temperature data, you are flying totally blind. 
>> Even on a production
>> design, this is how it’s done. The parts you fiddle are likely to be odd 
>> shaped chunks of metal 
>> that fit here or there. 
>> 
>> Bob
>> 
>>> On Mar 15, 2017, at 3:36 PM, Gilles Clement <clemg...@club-internet.fr> 
>>> wrote:
>>> 
>>> Hi, 
>>> I have a bunch of 5.184Mhz crystals. Large metallic tanks: HC33U case
>>> Maybe not OCXO grade, but I build a simple oscillator with a 4060 chip
>>> placed in a double oven, and reached 10E-9 short term stability up to 10sec 
>>> tau.
>>> Not bad, so wondering if I can get better with a more advanced design. 
>>> Gilles. 
>>> 
>>> 
>>>> Le 15 mars 2017 à 12:45, Bob Camp <kb...@n1k.org> a écrit :
>>>> 
>>>> Hi
>>>> 
>>>> Where do you plan on getting an OCXO grade crystal at an odd frequency 
>>>> like 
>>>> that? Much of the performance of a good OCXO is in the crystal. Doing a 
>>>> proper 
>>>> design on one is a lot of work. You *might* think that having a design for 
>>>> 5.00
>>>> MHz would give you a good design for 5.50 MHz. I have empirical 
>>>> evidence that
>>>> this isn’t the case. Many years later, I’m still utterly amazed that this 
>>>> is the way things
>>>> work in the crystal business ….( = it’s not just a design issue, it’s also 
>>>> a business decision) 
>>>> 
>>>> More or less the crystal needs to be:
>>>> 
>>>> 1) Cut specifically to have a turn at a temperature that makes sense for 
>>>> your application.
>>>> 2) A “large blank” design (for it’s frequency)
>>>> 3) In a cold weld package (most of the normal crystals are resistance weld)
>>>> 4) Run through a high vacuum / high temperature process
>>>> 5) Be plated with gold rather than something like silver or aluminum 
>>>> (unless it’s at VHF).
>>>> 6) Have a motional capacitance that makes sense for your EFC range ( 
>>>> normally = minimize)
>>>> 7) Preferably be an SC or modified SC cut. 
>>>> 
>>>> This is for a high stability part. The list does keep going on for a 
>>>> while, but that should 
>>>> give you a pretty good idea. 
>>>> 
>>>> Bob
>>>> 
>>>>> On Mar 15, 2017, at 3:11 AM, Gilles Clement <clemg...@club-internet.fr> 
>>>>> wrote:
>>>>> 
>>>>> Hi, 
>>>>> So what is the « best » design for DIY a high stability OCVXO ? 
>>>>> I am looking after one, needed for an exotic frequency : 5184kHZ 
>>>>> Thx, 
>>>>> Gilles. 
>>>>> 
>>>>> 
>>>>>> Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist 
>>>>>> <rich...@karlquist.com> a écrit :
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
>>>>>> 
>>>>>>> 
>>>>>>> Looking at oscillator circuits like the HP10811A will give some idea of 
>>>>>>> some of the additional complexity required for a o

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

> On Mar 15, 2017, at 3:55 PM, Dan Kemppainen  wrote:
> 
> Hi Bob,
> 
> If one prototypes any crystal oscillator, and runs it on a bench. Then builds 
> an 'oven' of sorts and runs it on the same bench. Would you expect to see any 
> improvement?

Sure, the XO likely moves 50 to 100 ppm over -30 to +70. You will cut that down 
to a couple of ppm. It’s much easier these 
days to just buy (or salvage) a cheap TCXO to get the same level of stability. 

One very basic issue: If I just grab a random crystal, it likely is a cut that 
does *not* have a useful turn temperature at all. For
a proper OCXO you need a crystal with a turn temperature in the practical range 
for your oven. There are many other 
issues. 

The key point (just as in the previous message) is that you must have good 
frequency vs temperature data to know if 
you are improving things or not. That involves having a real temperature test 
chamber than can be slewed in a controlled 
fashion and repeatably set to a sequence of temperatures. A typical run starts 
at room, steps down to cold (or up to hot). 
It then steps to the other end and finally steps back to room. Data is taken 
every 10C or so and analyzed to be sure that 
things are not all messed up. One obvious problem / issue would be drift during 
the run. A typical run takes several hours to
most of a day. 

Bob

> 
> In other words for a given oscillator (crystal and electronics, etc), will 
> there be any improvements in an oven compared to not in an oven? Or, are 
> there other things that outweigh the gains by temp controlling the whole 
> thing.
> 
> Yeah, this is a pretty open question, but I don't really have a feel for how 
> good an oscillator needs to be before an oven starts to improve things...
> 
> Dan
> 
> 
> 
> 
> On 3/15/2017 12:00 PM, time-nuts-requ...@febo.com wrote:
>> Hi
>> 
>> Where do you plan on getting an OCXO grade crystal at an odd frequency like
>> that? Much of the performance of a good OCXO is in the crystal. Doing a 
>> proper
>> design on one is a lot of work. You *might* think that having a design for 
>> 5.00
>> MHz would give you a good design for 5.50 MHz. I have empirical evidence 
>> that
>> this isn’t the case. Many years later, I’m still utterly amazed that this is 
>> the way things
>> work in the crystal business ….( = it’s not just a design issue, it’s also a 
>> business decision)
>> 
>> More or less the crystal needs to be:
>> 
>> 1) Cut specifically to have a turn at a temperature that makes sense for 
>> your application.
>> 2) A “large blank” design (for it’s frequency)
>> 3) In a cold weld package (most of the normal crystals are resistance weld)
>> 4) Run through a high vacuum / high temperature process
>> 5) Be plated with gold rather than something like silver or aluminum (unless 
>> it’s at VHF).
>> 6) Have a motional capacitance that makes sense for your EFC range ( 
>> normally = minimize)
>> 7) Preferably be an SC or modified SC cut.
>> 
>> This is for a high stability part. The list does keep going on for a while, 
>> but that should
>> give you a pretty good idea.
>> 
>> Bob
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

By most modern definitions, “high stability” starts around 1x10^-12 (1 ppt)  at 
a tau of 1 second to 
10 seconds. There are $20 eBay OCXO’s that run at that level.  With a 
fundamental crystal you 
aren’t going to get to that point. 

How much EFC range are you after? 

How good a CNC setup do you have?

What kind of temperature test setup do you have? 

Simply put, the design approach is a “test over temperature / collect data -> 
optimize” loop. 
Without good frequency vs temperature data, you are flying totally blind. Even 
on a production
design, this is how it’s done. The parts you fiddle are likely to be odd shaped 
chunks of metal 
that fit here or there. 

Bob

> On Mar 15, 2017, at 3:36 PM, Gilles Clement <clemg...@club-internet.fr> wrote:
> 
> Hi, 
> I have a bunch of 5.184Mhz crystals. Large metallic tanks: HC33U case
> Maybe not OCXO grade, but I build a simple oscillator with a 4060 chip
> placed in a double oven, and reached 10E-9 short term stability up to 10sec 
> tau.
> Not bad, so wondering if I can get better with a more advanced design. 
> Gilles. 
> 
> 
>> Le 15 mars 2017 à 12:45, Bob Camp <kb...@n1k.org> a écrit :
>> 
>> Hi
>> 
>> Where do you plan on getting an OCXO grade crystal at an odd frequency like 
>> that? Much of the performance of a good OCXO is in the crystal. Doing a 
>> proper 
>> design on one is a lot of work. You *might* think that having a design for 
>> 5.00
>> MHz would give you a good design for 5.50 MHz. I have empirical evidence 
>> that
>> this isn’t the case. Many years later, I’m still utterly amazed that this is 
>> the way things
>> work in the crystal business ….( = it’s not just a design issue, it’s also a 
>> business decision) 
>> 
>> More or less the crystal needs to be:
>> 
>> 1) Cut specifically to have a turn at a temperature that makes sense for 
>> your application.
>> 2) A “large blank” design (for it’s frequency)
>> 3) In a cold weld package (most of the normal crystals are resistance weld)
>> 4) Run through a high vacuum / high temperature process
>> 5) Be plated with gold rather than something like silver or aluminum (unless 
>> it’s at VHF).
>> 6) Have a motional capacitance that makes sense for your EFC range ( 
>> normally = minimize)
>> 7) Preferably be an SC or modified SC cut. 
>> 
>> This is for a high stability part. The list does keep going on for a while, 
>> but that should 
>> give you a pretty good idea. 
>> 
>> Bob
>> 
>>> On Mar 15, 2017, at 3:11 AM, Gilles Clement <clemg...@club-internet.fr> 
>>> wrote:
>>> 
>>> Hi, 
>>> So what is the « best » design for DIY a high stability OCVXO ? 
>>> I am looking after one, needed for an exotic frequency : 5184kHZ 
>>> Thx, 
>>> Gilles. 
>>> 
>>> 
>>>> Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist <rich...@karlquist.com> 
>>>> a écrit :
>>>> 
>>>> 
>>>> 
>>>> On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
>>>> 
>>>>> 
>>>>> Looking at oscillator circuits like the HP10811A will give some idea of 
>>>>> some of the additional complexity required for a overtone operation. 
>>>>> Dissecting a few ocxos may also be helpful. Some start with a 10MHz 
>>>>> crystal and a Colpitts sustaining stage and use a 74HC74 or similar to  
>>>>> divide the 10Mhz by 2 and drive the output pin. Even when a sinewave 
>>>>> output is required often a CMOS inverter drives the output pin via an LC 
>>>>> filter.
>>>>> 
>>>>> Bruce
>>>>> 
>>>> 
>>>> I don't agree here.  The 10811 is not a good tutorial for general 
>>>> oscillator design.  Because it is SC cut, it has a complicated
>>>> mode suppression network across the base emitter junction to
>>>> suppress mode B as well as the fundamental.
>>>> 
>>>> The E1983A oscillator uses the same crystal (in a low profile
>>>> package).  You can read my paper about it and see that I
>>>> used a very simple bridged tee oscillator circuit.  That is
>>>> all you need to select the right overtone and mode.
>>>> 
>>>> This is the same circuit that I used at Zeta Labs 40 years
>>>> ago to design hundreds of custom VCXO's, up to the 9th
>>>> overtone.  It simply worked every time, unlike various other
>>>> designs that were in use at Zeta.
>>>> 
>>>> Around 198

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

Where do you plan on getting an OCXO grade crystal at an odd frequency like 
that? Much of the performance of a good OCXO is in the crystal. Doing a proper 
design on one is a lot of work. You *might* think that having a design for 
5.00
MHz would give you a good design for 5.50 MHz. I have empirical evidence 
that
this isn’t the case. Many years later, I’m still utterly amazed that this is 
the way things
work in the crystal business ….( = it’s not just a design issue, it’s also a 
business decision) 

More or less the crystal needs to be:

1) Cut specifically to have a turn at a temperature that makes sense for your 
application.
2) A “large blank” design (for it’s frequency)
3) In a cold weld package (most of the normal crystals are resistance weld)
4) Run through a high vacuum / high temperature process
5) Be plated with gold rather than something like silver or aluminum (unless 
it’s at VHF).
6) Have a motional capacitance that makes sense for your EFC range ( normally = 
minimize)
7) Preferably be an SC or modified SC cut. 

This is for a high stability part. The list does keep going on for a while, but 
that should 
give you a pretty good idea. 

Bob

> On Mar 15, 2017, at 3:11 AM, Gilles Clement  wrote:
> 
> Hi, 
> So what is the « best » design for DIY a high stability OCVXO ? 
> I am looking after one, needed for an exotic frequency : 5184kHZ 
> Thx, 
> Gilles. 
> 
> 
>> Le 14 mars 2017 à 18:02, Richard (Rick) Karlquist  a 
>> écrit :
>> 
>> 
>> 
>> On 3/14/2017 4:03 AM, Bruce Griffiths wrote:
>> 
>>> 
>>> Looking at oscillator circuits like the HP10811A will give some idea of 
>>> some of the additional complexity required for a overtone operation. 
>>> Dissecting a few ocxos may also be helpful. Some start with a 10MHz crystal 
>>> and a Colpitts sustaining stage and use a 74HC74 or similar to  divide the 
>>> 10Mhz by 2 and drive the output pin. Even when a sinewave output is 
>>> required often a CMOS inverter drives the output pin via an LC filter.
>>> 
>>> Bruce
>>> 
>> 
>> I don't agree here.  The 10811 is not a good tutorial for general oscillator 
>> design.  Because it is SC cut, it has a complicated
>> mode suppression network across the base emitter junction to
>> suppress mode B as well as the fundamental.
>> 
>> The E1983A oscillator uses the same crystal (in a low profile
>> package).  You can read my paper about it and see that I
>> used a very simple bridged tee oscillator circuit.  That is
>> all you need to select the right overtone and mode.
>> 
>> This is the same circuit that I used at Zeta Labs 40 years
>> ago to design hundreds of custom VCXO's, up to the 9th
>> overtone.  It simply worked every time, unlike various other
>> designs that were in use at Zeta.
>> 
>> Around 1985, I got a consulting gig at Equatorial Communications
>> to redesign their 5th overtone VCXO.  Only about half of the
>> crystals would work in their circuit.  They had thousands
>> of "reject" crystals.  I just used my old Zeta circuit and
>> all the crystals started working again.
>> 
>> Equatorial owned the 10 meter dish that you used to see on
>> your right going south on 237 just before passing over
>> Central Expressway in Mountain View.
>> 
>> Rick N6RK
>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] WTB: GPSDO

[Bob Camp]

Hi


> On Mar 14, 2017, at 6:33 PM, Tim Lister  wrote:
> 
> On Fri, Mar 10, 2017 at 2:35 PM, Chris Albertson
>  wrote:
>> A GPSDO is not hard to make.  All you need is some way to compare the
>> phase of two signals, an XOR gate can do that.  Then a small $2
>> process moves the control voltage on the crystal.I tried one to
>> build the simplest GPSDO that could still work.   Got the parts count
>> down to about four or five and the cost well under $10 plus the OXO
>> which was about $20.  The simplest dumb one I could make keeps about
>> e-10.  Not great but enough for many uses.   I compared to my
>> Thunderbolt and I could see the phase advance and retreat.  Just a
>> little most sophistication and I likely could do much better but my
>> goal was to prove to myself that a GPSDO could be build VERY simply
>> with cheap parts
>> 
> 
> Hi Chris, that's good news that a GPSDO is that easy to make (at least
> a basic one) as that is exactly my medium term plan !

Actually it’s much easier. Just put a DVM on the XOR once a week and 
adjust your oscillator with a screwdriver. It saves *lots* of time and money.

Bob


> The issue of
> course is having something to test the newly built GPSDO against... I
> got one of the rehoused Trimble UCCM-based GPSDOs off ebay a while ago
> but haven't been super happy with it. It's quite a bit less sensitive
> than more modern GPS receivers and it often struggles to get even 1
> satellite with the indoor patch antenna. At one point both red alarm
> LEDs came on and stayed on despite power cycles - I eventually fixed
> that by taking it apart and finding and hitting a reset button on the
> board. Currently although I can talk to the unit over serial and it
> seems to respond, Lady Heather is not seeing any output from it.
> 
> Combined these things don't give me a great deal of confidence that
> this unit will act as a stable master reference. I was wondering if a
> second GPSDO like Russ linked to would work better (I have a ublox
> LEA-6T GPS already which I plan to use as the basis of the homebuilt
> GPSDO and it consistently sees many more satellites than the UCCM
> with a similar indoor antenna)  or put the money to getting an outdoor
> antenna mounted (don't feel happy drilling holes in the house myself)
> by someone. Do 2 GPSDOs tell you much more or just that each is
> different and you need a third to adjudicate ? (I can see a slippery
> slope looming from here...)
> 
> Cheers,
> Tim
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

Some (but not all) of the resonant structures in the MEMS parts are effectively 
multi 
resonator / multi peak structures. Because of this the phase noise has multiple 
major 
bumps in it as you get into the region of all the peaks. Thats not going to 
give you
great close in phase noise or ADEV. Since the manufacturers are often a bit 
unclear 
on “what’s inside” you need be a bit careful as you sort through the different 
parts out 
there. Even after sorting, you still run the risk of an “improved” design 
suddenly 
replacing the one you decided on. 

So much fun !!!

Bob 

> On Mar 14, 2017, at 8:39 AM, Magnus Danielson <mag...@rubidium.dyndns.org> 
> wrote:
> 
> Hi,
> 
> Some claims that MEMS will kill crystals. It will surely eat a good market 
> share, but I think there is applications where MEMS is not mature enough 
> compared to crystals.
> 
> Another aspect is that various forms of synthesis technologies now exists, so 
> that a high frequency CMOS oscillator is locked and divided down. Works 
> sufficiently well for a whole bunch of applications.
> 
> Again, your milage may vary and there is applications where you need the real 
> deal or the right stuff.
> 
> Cheers,
> Magnus
> 
> 
> On 03/14/2017 01:06 PM, Bob Camp wrote:
>> Hi
>> 
>>> On Mar 14, 2017, at 3:19 AM, Chris Albertson <albertson.ch...@gmail.com> 
>>> wrote:
>>> 
>>> I think what he means is that the typical device sold today has four
>>> terminals not two.  It looks like a crystal because it is inside a
>>> little silver can but has four lead wires Power, ground and "output"
>>> and the fourth lead might not be used.  It is an "XO" not an "X".
>>> 
>>> But I argue that every one of these device has a crystal inside.  So
>>> they still make crystals, just you don't see them
>> 
>> These days, they may well have a MEMS resonator in them. No quartz and
>> no crystal. Good luck on the close in noise if that’s what they are doing ….
>> 
>> Bob
>> 
>>> 
>>> On Mon, Mar 13, 2017 at 12:07 AM, Bryan _ <bpl...@outlook.com> wrote:
>>>> sorry, what do you mean by "complete oscillator" have outnumbered loose 
>>>> crystals?
>>>> 
>>>> 
>>>> -=Bryan=-
>>>> 
>>>> 
>>>> 
>>>> From: time-nuts <time-nuts-boun...@febo.com> on behalf of Richard (Rick) 
>>>> Karlquist <rich...@karlquist.com>
>>>> Sent: March 12, 2017 4:38 PM
>>>> To: Discussion of precise time and frequency measurement
>>>> Subject: Re: [time-nuts] Bye-Bye Crystals
>>>> 
>>>> I got a job in 1975 to design Konel's first synthesized radio, which
>>>> was to obsolete their crystal controlled radios.  That's over 40 years
>>>> ago.  The other trend (not mentioned) is that since 20 years ago or
>>>> so, complete oscillator sales have vastly outnumbered sales of loose
>>>> crystals.
>>>> 
>>>> Rick N6RK
>>>> 
>>>> On 3/11/2017 8:51 PM, Bob Camp wrote:
>>>>> Hi
>>>>> 
>>>>> International’s main business  was re-channeling non-synthesized radios 
>>>>> and replacing
>>>>> broken crystals in various pieces of com gear. It’s been a *lot* of years 
>>>>> since the last of the
>>>>> non-synthesized radios came out. The business probably has been dropping 
>>>>> off pretty steadily
>>>>> for many years …
>>>>> 
>>>>> Bob
>>>>> 
>>>>>> On Mar 11, 2017, at 10:39 PM, jimlux <jim...@earthlink.net> wrote:
>>>>>> 
>>>>>> On 3/11/17 4:30 PM, Scott McGrath wrote:
>>>>>>> From the tone of the letter it sounds like the bank cancelled line of 
>>>>>>> credit,
>>>>>> 
>>>>>> Or, he wants to retire and nobody wants to carry it on.  His dad started 
>>>>>> it in 1950, the son picked it up in 1970.  It's 47 years later.
>>>>>> 
>>>>>>> 
>>>>>>> Which is stupid given that much of their line is military which is 
>>>>>>> getting a huge boost in spending
>>>>>> 
>>>>>> Plenty of other crystal and oscillator manufacturers around.
>>>>>> 
>>>>>> There's also a change in what kinds o

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

> On Mar 14, 2017, at 8:49 AM, jimlux <jim...@earthlink.net> wrote:
> 
> On 3/14/17 5:04 AM, Bob Camp wrote:
>> Hi
>> 
>>> The cost difference between a complete oscillator package and a simple
>>> crystal is tiny.  The osc is often cheaper if you include board space or
>>> engineering time.
>> 
>> Purchased in volume, the difference it the price of a crystal vs a complete 
>> XO
>> is enormous. You will see at least a 10:1 cost savings on the crystal and 
>> likely
>> more than that.  Simply attaching a crystal to the internal oscillator 
>> inside a
>> chip is nearly zero engineering cost.  If your product is cost sensitive and
>> not super tight tolerance … you go with the crystal.
>> 
> 
> And that crystal business (gazillions of inexpensive 16 MHz crystals) is very 
> different from making an approximately 12 MHz crystal used in a VCXO that 
> will be FMed and multiplied up by 36 to make a 430 MHz transmitter, oh, and 
> that matches whatever temperature compensation scheme GE used in 1970.

Well, what GE did in 1970 was to test every single assembly over temperature 
(multiple times)  
and pick parts for that specific assembly to compensate it. There never was a 
magic single crystal 
design to match the compensation in a given unit ….

Bob

> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

> On Mar 14, 2017, at 3:19 AM, Chris Albertson <albertson.ch...@gmail.com> 
> wrote:
> 
> I think what he means is that the typical device sold today has four
> terminals not two.  It looks like a crystal because it is inside a
> little silver can but has four lead wires Power, ground and "output"
> and the fourth lead might not be used.  It is an "XO" not an "X".
> 
> But I argue that every one of these device has a crystal inside.  So
> they still make crystals, just you don't see them

These days, they may well have a MEMS resonator in them. No quartz and
no crystal. Good luck on the close in noise if that’s what they are doing ….

Bob

> 
> On Mon, Mar 13, 2017 at 12:07 AM, Bryan _ <bpl...@outlook.com> wrote:
>> sorry, what do you mean by "complete oscillator" have outnumbered loose 
>> crystals?
>> 
>> 
>> -=Bryan=-
>> 
>> 
>> 
>> From: time-nuts <time-nuts-boun...@febo.com> on behalf of Richard (Rick) 
>> Karlquist <rich...@karlquist.com>
>> Sent: March 12, 2017 4:38 PM
>> To: Discussion of precise time and frequency measurement
>> Subject: Re: [time-nuts] Bye-Bye Crystals
>> 
>> I got a job in 1975 to design Konel's first synthesized radio, which
>> was to obsolete their crystal controlled radios.  That's over 40 years
>> ago.  The other trend (not mentioned) is that since 20 years ago or
>> so, complete oscillator sales have vastly outnumbered sales of loose
>> crystals.
>> 
>> Rick N6RK
>> 
>> On 3/11/2017 8:51 PM, Bob Camp wrote:
>>> Hi
>>> 
>>> International’s main business  was re-channeling non-synthesized radios and 
>>> replacing
>>> broken crystals in various pieces of com gear. It’s been a *lot* of years 
>>> since the last of the
>>> non-synthesized radios came out. The business probably has been dropping 
>>> off pretty steadily
>>> for many years …
>>> 
>>> Bob
>>> 
>>>> On Mar 11, 2017, at 10:39 PM, jimlux <jim...@earthlink.net> wrote:
>>>> 
>>>> On 3/11/17 4:30 PM, Scott McGrath wrote:
>>>>> From the tone of the letter it sounds like the bank cancelled line of 
>>>>> credit,
>>>> 
>>>> Or, he wants to retire and nobody wants to carry it on.  His dad started 
>>>> it in 1950, the son picked it up in 1970.  It's 47 years later.
>>>> 
>>>>> 
>>>>> Which is stupid given that much of their line is military which is 
>>>>> getting a huge boost in spending
>>>> 
>>>> Plenty of other crystal and oscillator manufacturers around.
>>>> 
>>>> There's also a change in what kinds of crystals are needed.   I suspect 
>>>> most things being built and designed today use the crystal as a "master 
>>>> oscillator" that is used to drive some sort of synthesis chain. The need 
>>>> for "I have to have a 12.345,324 Hz crystal" is going away.
>>>> 
>>>> 
>>>>> 
>>>>>> On Mar 11, 2017, at 4:56 PM, Bryan _ <bpl...@outlook.com> wrote:
>>>>>> 
>>>>>> Disappearing or manufacturing just moving overseas?. Video at the bottom 
>>>>>> is interesting, classic.
>>>>>> 
>>>>>> 
>>>>>> http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/
>> [https://www.bing.com/th?id=OVF.LElrlkkbByR3K%2f6qfaeHjg=Api]<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>
>> 
>> So Long, and Thanks for all the 
>> Crystals<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>
>> hackaday.com
>> There was a time when anyone involved with radio transmitting -- ham 
>> operators, CB'ers, scanner enthusiasts, or remote control model fans -- had 
>> a collection of ...
>> 
>> 
>> 
>>>>>> 
>>>>>> 
>>>>>> 
>>>>>> -=Bryan=-
>>>>>> ___
>>>>>> time-nuts mailing list -- time-nuts@febo.com
>>>>>> To unsubscribe, go to 
>>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> time-nuts Info Page - American Febo 
>> Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
>> www.febo.com
>> time-nuts is a low volume, high SNR list for the discussion of precise time 
>&

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

> On Mar 14, 2017, at 4:44 AM, Hal Murray  wrote:
> 
> 
> artgod...@gmail.com said:
>> I'm not after quality - I do have an application in mind but it doesn't need
>> to compete with mass production. Just wondering if it's feasible to make
>> something crude that will resonate.
> 
> Are you doing this for fun or ???
> 
> Feasible?  Sure.  Cheaper?  That depends.
> 
> The cost difference between a complete oscillator package and a simple 
> crystal is tiny.  The osc is often cheaper if you include board space or 
> engineering time.

Purchased in volume, the difference it the price of a crystal vs a complete XO
is enormous. You will see at least a 10:1 cost savings on the crystal and likely
more than that.  Simply attaching a crystal to the internal oscillator inside a 
chip is nearly zero engineering cost.  If your product is cost sensitive and 
not super tight tolerance … you go with the crystal. 

Bob

> 
> Is your background digital or analog?  Do you want a sine wave or a clock?
> 
> My background is primarily digital.  If the chip you are using has 2 pins 
> setup to drive a crystal, you can probably get it to run reliably by 
> following the data sheet and/or app notes.  The usual recipe is 2 tiny caps 
> and a big resistor.  (big in resistance, not physically big)
> 
> An advantage of using a crystal with the on-chip amplifier that I didn't 
> mention last time is that you save the osc power if you power down that 
> corner of the chip.
> 
> If you want a sine wave, you are out of my comfort zone.  I'd probably look 
> in ham radio literature.
> 
> They make logic chips like a 74HCU04, U for unbuffered.  One of their uses is 
> for making oscillators.  I've never done it.  Try google.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

If your application is happy with 0.1% accuracy, you use a simple crystal that 
costs 
< 10 cents. If your application requires <0.001% accuracy, you probably are 
better 
off using a packaged oscillator. 

Bob

> On Mar 13, 2017, at 8:11 PM, Hal Murray  wrote:
> 
> 
> jim...@earthlink.net said:
>> what about cheap crystals for microcontrollers.. I think the Arduino,  for
>> instance, uses a crystal (and the oscillator electronics are inside  the
>> Atmel part) 
> 
> I assume you can save a few pennies if you use a raw crystal rather than an 
> oscillator.  That probably matters in high volume low cost applications.
> 
> Atmel has the technology for making oscillators.  That's an analog-ish corner 
> on what is mostly a digital chip.  A lot of their chips are low standby power 
> which generally means an older digital process with thicker oxides that don't 
> leak as much.  That probably makes analog corners easier, but I'm far from a 
> wizard at that area.
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

If you are not to picky, you can buy crystals in bulk for < 5 cents each. Why 
make
them from scratch? Best guess is that in small volume, they will cost you > $20 
each
to make. Labor cost something ….

Bob

> On Mar 13, 2017, at 9:09 PM, Adrian Godwin  wrote:
> 
> I'm not after quality - I do have an application in mind but it doesn't
> need to compete with mass production. Just wondering if it's feasible to
> make something crude that will resonate.
> 
> On 14 Mar 2017 1:00 a.m., "Hal Murray"  wrote:
> 
> 
> jim...@earthlink.net said:
>> what about cheap crystals for microcontrollers.. I think the Arduino,  for
>> instance, uses a crystal (and the oscillator electronics are inside  the
>> Atmel part)
> 
> I assume you can save a few pennies if you use a raw crystal rather than an
> oscillator.  That probably matters in high volume low cost applications.
> 
> Atmel has the technology for making oscillators.  That's an analog-ish
> corner
> on what is mostly a digital chip.  A lot of their chips are low standby
> power
> which generally means an older digital process with thicker oxides that
> don't
> leak as much.  That probably makes analog corners easier, but I'm far from a
> wizard at that area.
> 
> --
> These are my opinions.  I hate spam.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/
> mailman/listinfo/time-nuts
> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

…. ummm …… errr ….. 10 MHz sweet spot is a fiction. 

Roughly speaking the Q of a crystal is inversely proportional to the frequency. 
Drop the frequency 2:1 and the Q doubles. That
assumes you don’t run into size constraints. If your package is a bit larger, 
the sweet spot is 2.5 MHz. If it’s a bit smaller the sweet
spot is 30 MHz. As package size has gotten smaller and smaller over the last 70 
years, the idea of the “ideal frequency” has gone
up. This of course leads to the interesting question of reversing package size 
history …. If anybody has a few million dollars to toss 
around, it’s an interesting thing to dig into. 

Bob

> On Mar 13, 2017, at 8:03 PM, Jeff AC0C <keepwalking...@ac0c.com> wrote:
> 
> Making a finished crystal, especially a high-Q one of a target frequency far 
> removed from the 8-10 Mhz sweet spot, is definitely one of those projects 
> that is a lot harder than you would think it is.  I was down at ICM a few 
> years back when we were building some high-Q 70 Mhz VHF crystals for a filter 
> project and it was amazing the amount of stuff they had there.
> 
> 73/jeff/ac0c
> www.ac0c.com
> alpha-charlie-zero-charlie
> 
> -Original Message- From: Bob Camp
> Sent: Monday, March 13, 2017 5:19 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Bye-Bye Crystals
> 
> Hi
> 
> …. ummm …. errr … Add to that:
> 
> X-ray gear to work out the orientation of the (possibly natural) bar you are 
> sawing
> Lapping gear to get the blanks flat (as optically flat)
> Automated / sorting X-ray gear to figure out what’s what after they are lapped
> Rounding equipment to turn the square ones into round ones without damaging 
> them
> Contouring gear to put the proper shape on one or both sides (or pipes)
> Polishing gear to finish the shaping process
> Etching baths to get the surface to it’s final condition
> High vacuum cleaning to get all the crud off of all the parts before you do 
> much of anything with themA base plater to put on the initial electrodes
> Mounting fixtures to get the crystal into the holder
> Cement curing (generally vacuum based) gear
> Plate to frequency gear
> 
> That’s a short list, there actually is a bit more on a full list. The 
> cleaning gear can get pretty extensive depending on the end application.
> 
> Bob
> 
> 
>> On Mar 13, 2017, at 3:56 PM, Attila Kinali <att...@kinali.ch> wrote:
>> 
>> On Mon, 13 Mar 2017 15:01:39 +
>> Adrian Godwin <artgod...@gmail.com> wrote:
>> 
>>> What minimal equipment would you need to make your own crystals ?
>> 
>> The equipment is quite minimal:
>> 
>> * A diamond precision saw to cut the crystals
>> * Some tool to check the accuracy of the cut (orientation and thicknes)
>> * a lapping/grinding machine
>> * an electroplating machine (usually sputtering) for the electrodes.
>> * either some machine to produce the crystal holder yourself or buy them
>> * vacuum system to evacuate the crystal holder and to bake everything
>> * something to (cold) weld the case close
>> 
>> 
>> All of this can be put in a (relatively) small workshop.
>> The difficulty is also not producing quartz crystals
>> in holders. The difficulty controlling the whole process
>> to such an degree that you get high quality crystals
>> at the frequency you want.
>> 
>> If you managed to do that, you can further improve
>> your system by using a BVA[1,2] like geometry, where
>> the electrodes are not on the resonator itself but
>> on the surrounding crystal, which acts at the same
>> time as holder.
>> But be warned, many attempted to re-create the BVAs
>> but few succeeded... and none but Oscilloquartz ever
>> managed to produce a economically viable product.
>> 
>> 
>> Attila Kinali
>> 
>> [1] http://www.nature.com/articles/srep02132/figures/1
>> [2] http://www.nature.com/articles/srep02132/figures/2
>> 
>> -- 
>> It is upon moral qualities that a society is ultimately founded. All
>> the prosperity and technological sophistication in the world is of no
>> use without that foundation.
>>-- Miss Matheson, The Diamond Age, Neil Stephenson
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there. 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

> On Mar 13, 2017, at 7:12 PM, jimlux <jim...@earthlink.net> wrote:
> 
> On 3/13/17 3:19 PM, Bob Camp wrote:
>> Hi
>> 
>> …. ummm …. errr … Add to that:
>> 
>> X-ray gear to work out the orientation of the (possibly natural) bar you are 
>> sawing
>> Lapping gear to get the blanks flat (as optically flat)
>> Automated / sorting X-ray gear to figure out what’s what after they are 
>> lapped
>> Rounding equipment to turn the square ones into round ones without damaging 
>> them
>> Contouring gear to put the proper shape on one or both sides (or pipes)
>> Polishing gear to finish the shaping process
>> Etching baths to get the surface to it’s final condition
>> High vacuum cleaning to get all the crud off of all the parts before you do 
>> much of anything with themA base plater to put on the initial electrodes
>> Mounting fixtures to get the crystal into the holder
>> Cement curing (generally vacuum based) gear
>> Plate to frequency gear
>> 
>> That’s a short list, there actually is a bit more on a full list. The 
>> cleaning gear can get pretty extensive depending on the end application.
>> 
>> 
> 
> Just get the Kurt J. Lesker catalog out and start ordering

… since a lot of it goes into a single “never break vacuum” enclosure, it gets 
complicated fast. Toss in the 
fact that you want a *good* vacuum and there’s a lot of stainless steel all 
over the place. 

Bob

> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

…. ummm …. errr … Add to that:

X-ray gear to work out the orientation of the (possibly natural) bar you are 
sawing
Lapping gear to get the blanks flat (as optically flat)
Automated / sorting X-ray gear to figure out what’s what after they are lapped 
Rounding equipment to turn the square ones into round ones without damaging them
Contouring gear to put the proper shape on one or both sides (or pipes)
Polishing gear to finish the shaping process
Etching baths to get the surface to it’s final condition 
High vacuum cleaning to get all the crud off of all the parts before you do 
much of anything with themA base plater to put on the initial electrodes
Mounting fixtures to get the crystal into the holder
Cement curing (generally vacuum based) gear
Plate to frequency gear 

That’s a short list, there actually is a bit more on a full list. The cleaning 
gear can get pretty extensive depending on the end application. 

Bob


> On Mar 13, 2017, at 3:56 PM, Attila Kinali  wrote:
> 
> On Mon, 13 Mar 2017 15:01:39 +
> Adrian Godwin  wrote:
> 
>> What minimal equipment would you need to make your own crystals ?
> 
> The equipment is quite minimal:
> 
> * A diamond precision saw to cut the crystals
> * Some tool to check the accuracy of the cut (orientation and thicknes)
> * a lapping/grinding machine
> * an electroplating machine (usually sputtering) for the electrodes.
> * either some machine to produce the crystal holder yourself or buy them
> * vacuum system to evacuate the crystal holder and to bake everything
> * something to (cold) weld the case close
> 
> 
> All of this can be put in a (relatively) small workshop.
> The difficulty is also not producing quartz crystals
> in holders. The difficulty controlling the whole process
> to such an degree that you get high quality crystals
> at the frequency you want.
> 
> If you managed to do that, you can further improve
> your system by using a BVA[1,2] like geometry, where
> the electrodes are not on the resonator itself but
> on the surrounding crystal, which acts at the same
> time as holder.
> But be warned, many attempted to re-create the BVAs
> but few succeeded... and none but Oscilloquartz ever
> managed to produce a economically viable product.
> 
> 
>   Attila Kinali
> 
> [1] http://www.nature.com/articles/srep02132/figures/1
> [2] http://www.nature.com/articles/srep02132/figures/2
> 
> -- 
> It is upon moral qualities that a society is ultimately founded. All 
> the prosperity and technological sophistication in the world is of no 
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neil Stephenson
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

There also was an intermediate phase between channel frequency -> crystal 
frequency -> you buy a crystal and synthesizers.
My early fun and games at Motorola involved designing TCXO’s and OCXO’s that 
had non-replicable crystals in them. We shipped
them as a fully sealed unit. The compensation on them was very specific to the 
crystal involved. The assembly was such that
replacing the crystal likely broke the part in some way. At the very least it 
required you to re-weld the case on the TCXO’s. 

So yes, in this context (as opposed to the market in general) radios based on 
complete oscillators dominated a *long* time ago. 

Bob


> On Mar 13, 2017, at 3:07 AM, Bryan _ <bpl...@outlook.com> wrote:
> 
> sorry, what do you mean by "complete oscillator" have outnumbered loose 
> crystals?
> 
> 
> -=Bryan=-
> 
> 
> 
> From: time-nuts <time-nuts-boun...@febo.com> on behalf of Richard (Rick) 
> Karlquist <rich...@karlquist.com>
> Sent: March 12, 2017 4:38 PM
> To: Discussion of precise time and frequency measurement
> Subject: Re: [time-nuts] Bye-Bye Crystals
> 
> I got a job in 1975 to design Konel's first synthesized radio, which
> was to obsolete their crystal controlled radios.  That's over 40 years
> ago.  The other trend (not mentioned) is that since 20 years ago or
> so, complete oscillator sales have vastly outnumbered sales of loose
> crystals.
> 
> Rick N6RK
> 
> On 3/11/2017 8:51 PM, Bob Camp wrote:
>> Hi
>> 
>> International’s main business  was re-channeling non-synthesized radios and 
>> replacing
>> broken crystals in various pieces of com gear. It’s been a *lot* of years 
>> since the last of the
>> non-synthesized radios came out. The business probably has been dropping off 
>> pretty steadily
>> for many years …
>> 
>> Bob
>> 
>>> On Mar 11, 2017, at 10:39 PM, jimlux <jim...@earthlink.net> wrote:
>>> 
>>> On 3/11/17 4:30 PM, Scott McGrath wrote:
>>>> From the tone of the letter it sounds like the bank cancelled line of 
>>>> credit,
>>> 
>>> Or, he wants to retire and nobody wants to carry it on.  His dad started it 
>>> in 1950, the son picked it up in 1970.  It's 47 years later.
>>> 
>>>> 
>>>> Which is stupid given that much of their line is military which is getting 
>>>> a huge boost in spending
>>> 
>>> Plenty of other crystal and oscillator manufacturers around.
>>> 
>>> There's also a change in what kinds of crystals are needed.   I suspect 
>>> most things being built and designed today use the crystal as a "master 
>>> oscillator" that is used to drive some sort of synthesis chain. The need 
>>> for "I have to have a 12.345,324 Hz crystal" is going away.
>>> 
>>> 
>>>> 
>>>>> On Mar 11, 2017, at 4:56 PM, Bryan _ <bpl...@outlook.com> wrote:
>>>>> 
>>>>> Disappearing or manufacturing just moving overseas?. Video at the bottom 
>>>>> is interesting, classic.
>>>>> 
>>>>> 
>>>>> http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/
> [https://www.bing.com/th?id=OVF.LElrlkkbByR3K%2f6qfaeHjg=Api]<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>
> 
> So Long, and Thanks for all the 
> Crystals<http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/>
> hackaday.com
> There was a time when anyone involved with radio transmitting -- ham 
> operators, CB'ers, scanner enthusiasts, or remote control model fans -- had a 
> collection of ...
> 
> 
> 
>>>>> 
>>>>> 
>>>>> 
>>>>> -=Bryan=-
>>>>> ___
>>>>> time-nuts mailing list -- time-nuts@febo.com
>>>>> To unsubscribe, go to 
>>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> time-nuts Info Page - American Febo 
> Enterprises<https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts>
> www.febo.com
> time-nuts is a low volume, high SNR list for the discussion of precise time 
> and frequency measurement and related topics. To see the collection of prior 
> postings to ...
> 
> 
> 
>>>>> and follow the instructions there.
>>>> ___
>>>> time-nuts mailing list -- time-nuts@febo.com
>>>> To unsubscribe, go to 
>>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> time-nut

Re: [time-nuts] Bye-Bye Crystals

[Bob Camp]

Hi

International’s main business  was re-channeling non-synthesized radios and 
replacing 
broken crystals in various pieces of com gear. It’s been a *lot* of years since 
the last of the 
non-synthesized radios came out. The business probably has been dropping off 
pretty steadily 
for many years …

Bob

> On Mar 11, 2017, at 10:39 PM, jimlux  wrote:
> 
> On 3/11/17 4:30 PM, Scott McGrath wrote:
>> From the tone of the letter it sounds like the bank cancelled line of credit,
> 
> Or, he wants to retire and nobody wants to carry it on.  His dad started it 
> in 1950, the son picked it up in 1970.  It's 47 years later.
> 
>> 
>> Which is stupid given that much of their line is military which is getting a 
>> huge boost in spending
> 
> Plenty of other crystal and oscillator manufacturers around.
> 
> There's also a change in what kinds of crystals are needed.   I suspect most 
> things being built and designed today use the crystal as a "master 
> oscillator" that is used to drive some sort of synthesis chain. The need for 
> "I have to have a 12.345,324 Hz crystal" is going away.
> 
> 
>> 
>>> On Mar 11, 2017, at 4:56 PM, Bryan _  wrote:
>>> 
>>> Disappearing or manufacturing just moving overseas?. Video at the bottom is 
>>> interesting, classic.
>>> 
>>> 
>>> http://hackaday.com/2017/03/11/so-long-and-thanks-for-all-the-crystals/
>>> 
>>> 
>>> 
>>> -=Bryan=-
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Thunderbolt Rollover Testing

[Bob Camp]

Hi

> On Mar 6, 2017, at 1:38 AM, Mark Sims  wrote:
> 
> Does it have a saved/surveyed position?  With a saved position you can 
> reasonable time performance with 1 sat.   Without a saved position all bets 
> are off,  there is no way for the receiver to determine the 
> receiver/satellite clock difference.
> 
> Trimble reports that the device is in "over-determined clock" mode if that is 
> how it is configured.  Even if it is in "over-determined clock" mode the 
> receiver may not have enough data to do anything effective.   Trimble's 
> overdetermined clock mode is basically a "position hold" mode.

I very much prefer the “position hold” term for what it is doing compared to 
Trimble’s “overdetermined” description. Overdetermined suggests that it has 
more information than it needs to come up with the time.

Bob

> 
> 
> 
>> I just re-checked this with a Resolution-T, and it does go into OD mode with 
>> all but 1
> SV masked from cold restart using a real SV.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] RFDO - Experience and questions

[Bob Camp]

Hi

One way to “cheat” at recovering a time signal is to demodulate it with
known information. Once you know the information from the first “frame”
of data (time, date, etc) you can predict what the information in the next
frame will be. Yes it does take a little work. If the signal is completely 
defined 
(no extra data about the weather forecast or something like that) you can
reduce your bandwidth significantly.

Bob

> On Mar 5, 2017, at 11:42 PM, Iain Young  wrote:
> 
> On 05/03/17 20:23, paul swed wrote:
> 
>> Gilles what signal is that at 162KHz. A European station? Nice thats its C
>> controlled.
> 
> That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
> the AM Station France Inter as well, but that went when France turned
> off all LW, MW, and LORAN stations at the end of 2016.
> 
> The Time Signal is Phase Modulated (I have a gnuradio decoder which
> works very well if anyone is interested)
> 
> See https://en.wikipedia.org/wiki/TDF_time_signal and
> https://en.wikipedia.org/wiki/Allouis_longwave_transmitter
> 
> With no AM modulation, there are obvious benefits with regards to using
> it as a frequency reference. Average phase and frequency deviation is
> zero over 200msec (see link above for details)
> 
> 
> Iain
> 
> PS, The signal is used by the French railways SNCF, the electricity
> distributor ENEDIS, airports, hospitals according to the Allouis link
> above
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Fwd: Dusty 53131A

[Bob Camp]

Hi

53131’s are dust magnets. It is not at all uncommon for them to fill up with 
dust, 
overheat, and die. Popping them open every 10 years or so to clean them out is
well worth the effort. 

Bob

> On Mar 5, 2017, at 8:54 PM, Scott Stobbe  wrote:
> 
> Recently the fan in my 53131 has been making a pretty awful sound, so its
> time to replace it. When I disassembled the counter I found the trim cap
> had turned into a fur ball. Not that it really matters since it runs on an
> external reference, but its interesting to see if the dust has any effect.
> See https://www.flickr.com/photos/147407087@N06/32427230764/. So with the
> unit disassembled I logged the effect of removing the dust by logging a
> GPSDO during the cleaning process.
> 
> Must of the dust was around the shroud of the trim cap. Near the mounting
> terminals there was fairly minimal amounts of dust. At least in this
> instance, if the dust had any impact on frequency, its orders of magnitude
> below the thermal instability of the AT crystal.
> 
> The crystal appears to be in a to-39 3-lead package. It is also
> freestanding directly in front of the exhausting cooling fan...
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Thunderbolt Rollover Testing

[Bob Camp]

Hi

> On Mar 5, 2017, at 6:31 AM, Trevor N.  wrote:
> 
> On Sat, 4 Mar 2017 20:39:45 -0800, you wrote:
> 
>> Matthias Jelen did a test on the Trimble Thunderbolt here:
>> 
>> https://www.febo.com/pipermail/time-nuts/2014-September/086664.html
>> https://www.febo.com/pipermail/time-nuts/2015-May/091805.html
>> https://www.febo.com/pipermail/time-nuts/2015-May/091825.html
>> 
> 
> 
> Thanks for the links, I didn't see the 2015 test.  Currently the older
> Spirent simulators are going for very resonable prices on the 'bay.
> The GSS4100 can be had for under $200 and 6100s frequently pop up for
> $150.

One thing a 6100 will let you do is to calibrate the PPS out of your “gizmo” to 
+/- 5 ns (one sigma). While it’s 
not an impressive number by TimeNuts standards, it is one of the few ways to 
get that job done. 

>  Anything newer is still very expensive, though. It may be
> necessary to use a multichannel simulator for newer receivers (or
> multiple synchronized single channel units), as I haven't yet been
> able to get the Trimble Resolution boards to go into overdetermined
> mode with a single simulated SV.

It would be a bit alarming if you *could* get it to show overdetermined with 
only a single clock source :)

Bob

> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Coming to a drive-way near you: Optical Lattice clocks

[Bob Camp]

Hi

> On Feb 24, 2017, at 5:02 AM, Michael Wouters <michaeljwout...@gmail.com> 
> wrote:
> 
> On Fri, Feb 24, 2017 at 10:27 AM, Bob Camp <kb...@n1k.org> wrote:
>> Hi
>> 
>> I agree with their premise that to be useful you need transportable clocks. 
>> I’m not quite sure
>> that something the size (and weight) of a pickup truck is really 
>> transportable. Yes one can
>> move it around (unlike a small mountain)  …. Transporting something like 
>> that from here to
>> Europe and back *would* make the charges FedEx comes up with on a  40Kg box 
>> look
>> cheap though :)
>> 
>> Bob
> 
> I suspect that it's really only meant to be driven around to labs in
> Europe with optical clocks, like LNE-SYRTE and NPL.
> I think that you would repack it if you were shipping it overseas.
> 
> My one experience of something remotely like this was delivery of our
> frequency comb (two full-height 19 inch racks plus the laser on a
> large breadboard) from Germany to Australia. It was all working the
> same day it was unpacked. But no UHV system of course.

It’s the things like keeping vacuum systems running that while it’s possible, 
is not trivial. 
I sort of wonder if “transportation” involves one person driving the truck and 
two people
riding in back as “minders” for all the gear.

This is indeed cool stuff. Their clock is amazing. I’d love to have one. It’s 
still a massive
piece of gear. 

Bob

> 
> The Chinese one is a bit simpler: it's a single-ion Paul trap, rather
> than a lattice clock. Probably less control electronics are needed
> too, so maybe it's a bit more mobile.
> 
> Cheers
> Michael
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Coming to a drive-way near you: Optical Lattice clocks

[Bob Camp]

Hi

I agree with their premise that to be useful you need transportable clocks. I’m 
not quite sure
that something the size (and weight) of a pickup truck is really transportable. 
Yes one can 
move it around (unlike a small mountain)  …. Transporting something like that 
from here to 
Europe and back *would* make the charges FedEx comes up with on a  40Kg box 
look 
cheap though :)

Bob

> On Feb 23, 2017, at 3:23 PM, Poul-Henning Kamp  wrote:
> 
> Have we talked about this yet ?
> 
> https://arxiv.org/abs/1609.06183
> 
> https://arxiv.org/abs/1607.03731
> 
> 
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] TTimelab question

[Bob Camp]

Hi


> On Feb 21, 2017, at 11:45 PM, Mark Sims  wrote:
> 
> I doubt that it is something TAPR would do.   Building complete systems gets 
> into all sorts of issues (mainly regulatory).

There’s also the issue of cost. If you need to sell maybe 200 gizmos at $100 to 
make things work, The same process is a bit more 
exciting when it’s 200 gizmos at $800. In the first case, somebody needs to 
front the money for a $20,000 project. In the second 
case they may need to take out a second mortgage. If 20 of the $100 devices 
don’t sell, they have $2K in inventory to write off.
In the second case they have $16K. As you can quickly see on their web site, 
some of their projects hang around in inventory 
for a *long* time.  Yes, that’s all in sales dollars to make the math easy. 
Somehow I doubt that TAPR is a high margin / high profit
organization :)

Bob

>   But it is easy enough to build.   They sell a nice case that the RPI3 and 
> touchscreen mounts in.  The PI+touchscreen+case sells for around $110.   The 
> TICC(s) connect to it via USB.  
> 
> There are also some Win10 tablets with 1024x600 touch screens that sell for 
> around $60 (apparently Microsoft doesn't charge manufacturers for Win10 on 
> tablets with small/low res screens).
> 
> I  am thinking about laying out a front-end board for the TICC.  It would 
> have some switchable (relay?) 50 ohm input terminators,  switchable PICDIV 
> dividers for PPS/1MHz/5MHz/10MHz/15MHz (or 2.5 MHz)  inputs,  footprints for 
> a decent reference oscillator (MV89/8663/DIP/etc), and a 12V to 5V (3A?) 
> power converter for the  TICC and PI... most of the better surplus 
> oscillators run off of 12V.  Also maybe add a data multiplexer for combining 
> the outputs of two TICC boards into one data stream (but Heather could do 
> that in software).  John has some ideas for a similar board.  
> 
> -
> 
>> Wow!  If you can persuade John and TAPR to produce that, I would be there
> with my chequebook before the ink had dried on the web-page! :-)
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPSdecoding cards

[Bob Camp]

Hi


> On Feb 21, 2017, at 9:50 PM, Trevor N.  wrote:
> 
> On Tue, 21 Feb 2017 07:37:34 -0500, BC wrote:
>> 
>> Some 1588 chip sets have (or had, I haven’t looked recently) external sync 
>> pins. 
>> This does get into the whole, what’s a motherboard / what’s a peripheral 
>> debate. Plugging in a 1588 card to get that pin probably no longer counts
>> as a simple solution. If plugging in a card *does* count then that opens up 
>> a lot of possible options. 
>> 
>> Bob
> 
> I found while looking at the datasheets for newer Intel server
> ethernet cards that they have the ability to timestamp GPIO pin
> transitions, but none of them have their internal timebase
> synchronized to a counter in the CPU. It looks like they are clocked
> from a separate XO on the card.

Everything on a motherboard traces back to this or that XO. None of the time 
sources are anything that would get you excited as a frequency standard. Linking
them together can be exciting. Replacing this or that one with a better 
frequency
source *is* possible in some cases. If you are going to replace one, why not
replace several :)

Bob

>  Maybe if it was synchronized to the
> PCIe clock / BCLK  they could take advantage of that new Always
> Running Timer in Skylake processors.  I'm surprised that Intel hasn't
> made a big deal about it. Support for it was added in the Linux e1000e
> driver early last year.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPSdecoding cards

[Bob Camp]

Hi


> On Feb 20, 2017, at 9:26 PM, Trevor N.  wrote:
> 
> SA6CID wrote:
>> 
>> So, I thought actually of the jitter added on the way between our
>> accurate source (GPS rx), until we can capture our timer. How much can
>> this be? As far as I see we don't have a capture mode for the HPET. But,
>> if we have to do it in software, we get more than 100 ns jitter. I just
>> measured 60-80 ns for a instruction cache miss, with Intels mlc software.
>> Overall I would guess > 500 ns, are there measurements on this?
> 
>> This then defines some lower bound of what can be archived for
>> synchronizing the clock off the OS. Also hardware time stamping on a
>> dedicated PPS card (or PTP ethernet card) does not help unless the clock
>> on the card is synchronized to the clock used by the OS.
>> 
> 
> On Intel processors newer than the core2 it appears that there are no
> input pins that can be polled or used as an interrupt source.  Current
> AMD processors still have LINT0 and LINT1 pins that can be polled
> through the XAPIC interface, but using them would require modifying
> the motherboard to temporarily disconnect them from their usual
> sources. It seems likely that a transition on those pins could be
> timestamped within a few tens of ns.
> 
> An option for Linux kernel 4.6 or newer on Skylake processors when
> using PTP on the chipset ethernet would be to use the
> PTP_SYS_OFFSET_PRECISE ioctl to eliminate the problem you mentioned in
> the quoted text. See
> https://patchwork.kernel.org/patch/8497611/
> https://patchwork.kernel.org/patch/8497621/
> https://lwn.net/Articles/670081/
> It looks like the chipset and CPU share an "Always Running Timer"
> which the chipset can sample in sync with the ethernet PTP, USB[2] and
> audio timing registers, and it has a defined relationship to the CPU
> TSC. I didn't spot a way to timestamp a GPIO pin transition in the
> chipset datasheet, so this sort of kicks the can down the road when
> using PTP. It might be possible to use this to improve PPS over USB.  
> 
> Skylake chipsets have three 16550-compatible UARTS, so depending on
> how they are connected internally (might be on the LPC bus) the line
> status signals may have very low read latency. It looks like they are
> supported in Linux 4.3 and newer; has anyone tested them?
> 
> For now I've focused on using parallel port cards for PPS capture. The
> machine I'm using has a Q67 chipset and i5-2500 processor (the Q67 is
> one of the last chipsets with native parallel PCI). There is no option
> in the BIOS to disable clock spread-spectrum so it's probably active.
> The system XO was replaced with an IDT525 so I can use 10MHz sources.
> I added a polling mode and PPS echo to the Linux 4.1 pps_parport
> driver.
> 
> Using a Lava parallel PCI card, port reads and writes take an average
> of 962ns when done in a calibration loop with the processor TSC. For
> measurements I'm using a TIC hooked to the PPS input and echo output,
> and Miroslav Lichavar's ppsallan program[3].  The counter I'm using
> only has GPIB and I don't yet have an interface card, so I can only do
> short tests with it at the moment since I have to watch it.  I've
> listed some results below with a test time of 1 minute. The system
> oscillator and PPS source is an Endrun Technologies Praecis Cf, so all
> the data below should be showing only the PPS capture error.

Some 1588 chip sets have (or had, I haven’t looked recently) external sync 
pins. 
This does get into the whole, what’s a motherboard / what’s a peripheral 
debate. Plugging in a 1588 card to get that pin probably no longer counts
as a simple solution. If plugging in a card *does* count then that opens up 
a lot of possible options. 

Bob

> 
> --Driver in polling mode with no system load:
> The minimum observed interval between the PPS input and echo was
> 1.3us, maximum interval was 2.3us, eyeball-average 1.9us, and the 1t
> adev was 513ns. attachment:
> adev-praecis-lavanew-poll-noload-1min-04.plog
> 
> --Driver in polling mode with high system load:
> min 1.3us, max 2.4us, avg 1.9us, 1t adev 549ns
> adev-praecis-lavanew-poll-load-1min-01.plog
> 
> --Driver in interrupt mode with no system load:
> min 2.4us, max 3.1us, avg 2.7us, 1t adev 467ns
> adev-praecis-lavanew-int-noload-1min-01.plog
> 
> --Driver in interrupt mode with high system load:
> min 2.4us, max 4.1us avg 2.8us, 1t adev 533ns
> adev-praecis-lavanew-int-load-1min-01.plog
> 
> After subtracting the echo's port write time, polling mode can go
> below 400ns delay.  This is below the 962ns read time, but is probably
> valid since the PPS edge could occur between when the card has decoded
> the read command and when it samples the port pins to place on the
> bus. 962ns latency seems very high for parallel PCI -- it should be
> able to achieve below 300ns. The lava card may be using wait cycles to
> throttle down to standard LPT speeds. The card uses an FPGA so it
> might be possible to improve its 

Re: [time-nuts] Have done some more cutting on the Cs beam tube

[Bob Camp]

Hi

The high performance tube runs at a higher beam current than the standard
tube. One would guess that a bit more Cs boils off to supply the beam 
at the higher temperature. There are rumors that the high performance tubes
were “selected” out of the batch. Even if that was once true, who knows 
if it’s true today …

Bob

> On Feb 19, 2017, at 3:04 PM, Bill Dailey  wrote:
> 
> Is it possible that the higher temp keeps the tube "cooked off?"
> 
> Bill Dailey
> 
> 
>> On Feb 19, 2017, at 12:54 PM,   wrote:
>> 
>> Hi,
>> 
>> The tiny coil inside the beam path is the low frequency coil used for DC
>> testing of the tube.
>> 
>> The tube shown is a standard performance tube and has no degaussing coil.
>> 
>> The flat windings on top of the shield are the C-field winding.
>> 
>> The high performance cavity is even "prettier".
>> 
>> You can see one at http://www.leapsecond.com/pages/cesium-tube/
>> 
>> Towards the bottom you can see the C-field windings in slots around the
>> circumference of the cavity.
>> 
>> BTW in 5071A tubes there is no internal difference between the STD and
>> High Performance tubes.
>> 
>> They just run at different temperatures! Saves having to build two
>> different tubes!
>> 
>> Some more interesting 5071A tube info will post in a couple weeks!!! 
>> 
>> (Hint: Run your 5071A HiPerf tube at the Std tube temperature to extend
>> life!!!???)
>> 
>> Cheers,
>> 
>> Corby
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

The point is that some chip sets have better access to timer / counters than 
others do.
One of the Soekris (sp?) boards is an example of this. We also are moving into 
an era where
fairly fancy ARM CPU’s are grafted onto FPGA’s. Once you have that, you are no 
longer
dependent on somebody else to brew up the peripheral you need. 

Bob



> On Feb 18, 2017, at 10:45 AM, Thomas Petig <tho...@petig.eu> wrote:
> 
> Hi Bob,
> 
> On Sat, Feb 18, 2017 at 08:36:51AM -0500, Bob Camp wrote:
>> Hi
>> 
>>> On Feb 18, 2017, at 4:53 AM, David J Taylor <david-tay...@blueyonder.co.uk> 
>>> wrote:
>>> 
>>> Hi,
>>> 
>>> I was wondering whether there is some data/information available on the
>>> claimed +/- 100 ns jitter?
>> 
>> 
>> I guess the previous was not complete enough.
>> 
>> I routinely measure PPS jitter on GPS modules down well below 10 ns on a 
>> 53131.
>> That’s after sawtooth correction is applied. Without sawtooth correction, 
>> the +/- 24
>> or +/- 12 or +/- 1.25 ns of the sawtooth adds into that.
>> 
>> The reference used is an HP 5071 with a high performance tube option.
> 
> I agree, in this setup we get this performance. I also agree that using
> timers in capture mode on microprocessors will give this performance, as
> you wrote before.
> 
> But as we where discussing the performance between capturing some PPS
> via PCIe, serial i/o from the chipset, or some USB cable. The reference
> clock is here the clock of the CPU, or OS. This clock is of course not
> very precise, but the reason for capturing the PPS might be we want to
> run some NTP server.
> 
> So, I thought actually of the jitter added on the way between our
> accurate source (GPS rx), until we can capture our timer. How much can
> this be? As far as I see we don't have a capture mode for the HPET. But,
> if we have to do it in software, we get more than 100 ns jitter. I just
> measured 60-80 ns for a instruction cache miss, with Intels mlc software.
> Overall I would guess > 500 ns, are there measurements on this?
> 
> This then defines some lower bound of what can be archived for
> synchronizing the clock off the OS. Also hardware time stamping on a
> dedicated PPS card (or PTP ethernet card) does not help unless the clock
> on the card is synchronized to the clock used by the OS.
> 
> So, can we do better?
> 
> Best regards,
>Thomas
>DK6KD
>SA6CID
> 
>> 
> 
>> Bob
>> 
>>> 
>>> Regarding the PPS -> USB (using the CTS line of a FTDI FT232R), I
>>> plotted, using some lines of Python, the time offset as attached. Just
>>> to get an overview how it is 'worst case', i.e., user program, python,
>>> etc. The 1PPS signal comes from a GPS rx.
>>> Looks like a standard deviation of around 150 us.
>>> y-axis:  measured pps offset from full second (computer time) in us,
>>> x-axis pps pulse number.
>>> 
>>> On the long term it looks interesting (while measuring I played with the
>>> NTP server on this computer)
>>> Until ca. second 1: ntpd synchronization via internet
>>> Until ca. second 17000: made an additional LAN NTP server (GPS) available
>>> Until the end: replaced ntpd with chrony (still using internet and local
>>> servers)
>>> 
>>> Interesting points:
>>> -It looks surprisingly bad with using the normal ntpd (especially, there
>>> is not really an improvement having an local GPS based server
>>> available, did I do something wrong? Only the offset changes by ca. 3
>>> ms.)
>>> -It looks surprisingly good with chrony. But there are continuously
>>> outliers of up to 4500 us, is this a result of the chrony control loop?
>>> The time is wandering around with ntpd, but has less jitter.
>>> 
>>> Conclusion:
>>> Despite the 150 us stddev, the using PPS over USB gives some interesting
>>> inside of what the local ntp server is actually doing. It looks to me
>>> like it would be an improvement to use it when using ntpd, but not when
>>> using chrony.
>>> 
>>> Best regards,
>>> Thomas
>>> DK6KD
>>> SA6CID
>>> 
>>> PS:
>>> Raw data is here, if you want to zoom in: (1.7 MiB, one row per PPS
>>> offset in us)
>>> http://petig.eu/pps-usb.txt
>>> =
>>> 
>>> Thomas,
>>> 
>>> I've done some tests with PPS over USB with Windows some time back, which 
>>> showed that PPS?USB could be better than

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

> On Feb 18, 2017, at 4:53 AM, David J Taylor  
> wrote:
> 
> Hi,
> 
> I was wondering whether there is some data/information available on the
> claimed +/- 100 ns jitter?


I guess the previous was not complete enough.

I routinely measure PPS jitter on GPS modules down well below 10 ns on a 53131. 
That’s after sawtooth correction is applied. Without sawtooth correction, the 
+/- 24 
or +/- 12 or +/- 1.25 ns of the sawtooth adds into that.

The reference used is an HP 5071 with a high performance tube option. 

Bob

> 
> Regarding the PPS -> USB (using the CTS line of a FTDI FT232R), I
> plotted, using some lines of Python, the time offset as attached. Just
> to get an overview how it is 'worst case', i.e., user program, python,
> etc. The 1PPS signal comes from a GPS rx.
> Looks like a standard deviation of around 150 us.
> y-axis:  measured pps offset from full second (computer time) in us,
> x-axis pps pulse number.
> 
> On the long term it looks interesting (while measuring I played with the
> NTP server on this computer)
> Until ca. second 1: ntpd synchronization via internet
> Until ca. second 17000: made an additional LAN NTP server (GPS) available
> Until the end: replaced ntpd with chrony (still using internet and local
> servers)
> 
> Interesting points:
> -It looks surprisingly bad with using the normal ntpd (especially, there
> is not really an improvement having an local GPS based server
> available, did I do something wrong? Only the offset changes by ca. 3
> ms.)
> -It looks surprisingly good with chrony. But there are continuously
> outliers of up to 4500 us, is this a result of the chrony control loop?
> The time is wandering around with ntpd, but has less jitter.
> 
> Conclusion:
> Despite the 150 us stddev, the using PPS over USB gives some interesting
> inside of what the local ntp server is actually doing. It looks to me
> like it would be an improvement to use it when using ntpd, but not when
> using chrony.
> 
> Best regards,
>  Thomas
>  DK6KD
>  SA6CID
> 
> PS:
> Raw data is here, if you want to zoom in: (1.7 MiB, one row per PPS
> offset in us)
> http://petig.eu/pps-usb.txt
> =
> 
> Thomas,
> 
> I've done some tests with PPS over USB with Windows some time back, which 
> showed that PPS?USB could be better than LAN-sync alone, but that also 
> included a reduction of the poll interval from possibly 64 seconds for LAN 
> sync to 16 seconds for PPS sync, which may have influenced the results.
> 
> It would be helpful to have some units on the axes - 1 what? 
> I'm guessing microseconds
> 
> For comparison, here is a Raspberry Pi running NTP, with the reported offset 
> plotted against time.
> 
> http://www.satsignal.eu/mrtg/raspi14_ntp_3.html
> 
> This Raspberry Pi (running a seismic detector) is using an Ethernet 
> connection via Power-line Ethernet (yes, I know, QRM etc. etc.), and a couple 
> of switches to a very good stratum-1 server.  I would estimate from your 
> graph that the jitter in offset is about 1 millisecond peak-to-peak, but it 
> seems that I get less than that - perhaps 100 microseconds peak-to-peak with 
> occasional excursions outside that.  This is with the latest reference 
> version of NTP.
> 
>remote   refid  st t when poll reach   delay   offset jitter
> ==
> *192.168.0.20.GPS.1 u   17   32  377   12.3510.000 0.428
> +192.168.0.11.uPPS.   1 u2   32  377   12.432   -0.106 0.824
> -192.168.0.3 .kPPS.   1 u   13   32  377   21.366   -4.524 0.804
> +192.168.0.83.kPPS.   1 u   27   32  377   21.614   -4.511 1.206
> uk.pool.ntp.org .POOL.  16 p-   6400.0000.000 0.001
> -193.150.34.2133.150.251.233  3 u   38   64  137   32.3432.738 1.477
> -80.87.128.1794.125.129.7 3 u   30   64  375   53.337   -1.225 1.516
> -192.146.137.13  82.148.230.254   2 u   56   64  377   46.0892.220 2.535
> -129.250.35.250  249.224.99.213   2 u  169   64  214   42.499   -3.015 12.507
> -213.130.44.252  145.238.203.14   2 u  487   64  200   37.210   -0.725 13.232
> 
> 73,
> David GM8ARV
> -- 
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-tay...@blueyonder.co.uk
> Twitter: @gm8arv 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Installing GPS Antenna

[Bob Camp]

Hi

Let’s back off a bit here. 

If the chimney is above the rest of the house, simply putting the antenna a 
foot or
two above the chimney will get you past the immediate issues of the house 
blocking
or reflecting stuff. 

If the top of the chimney has a view to the south down to about 10 degrees off 
the 
horizon *and* it maintains that for most of a +/- 100 degree arc, that is doing 
fine.

If the application is just timing, having a mount that does not move around a 
lot 
is a really good idea. 

With any antenna, putting it up higher than needed simply makes it a better 
lightning 
target (you *will* have proper grounding and suppression on this antenna, it 
still 
is not perfect).

On a GPSDO with a good sky view, you may well set the elevation mask to 
something 
like 20 or even 30 degrees to improve the timing performance. When you do, all 
the effort to get a sky view down to 10 degrees becomes a bit less worthwhile. 

=

So: what is the reason for getting the antenna 15 feet above the chimney?

Bob

> On Feb 18, 2017, at 12:57 AM, time...@metachaos.net wrote:
> 
> I have finally ordered a GPSDO (probably get here in April). In the meantime,
> I have the GPS antenna (Luctel, 26Db). I picked up a 20' solid section of 1 
> 1/4"
> copper pipe at the plumbing store with the intention of mounting it to my
> chimney.
> 
> My question is about the stability of that mounting. I expect that 16 or 17
> feet of the pipe will be above the chimney. The weight of the GPS antenna is
> trivial. The effective cross section area of the pipe is very small as well,
> so I would think that wind effects would be pretty small even for a good
> breeze.
> 
> Will that be sufficiently stable, or will I need to include guy wires? If so,
> are there any recommendations in that area. I don't really have any experience
> putting up antennas. I know that TV antennas are much heavier and, even though
> not mounted as high, still 10' or so is common without guy wires.
> 
> Thanks.
> 
> Michael
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

Roughly speaking, if you have a 10 MHz clock driving a timer and the pin 
latches data 
from that timer, you get 100 ns “buckets and +/- 100 ns “jitter”.  You can find 
MCU’s that
will do this for < $1. If you go crazy, you can spend < $10 and still get a 
very fancy MCU
on a board with all the support “stuff”. That would get you into > 100 MHz 
clocks driving
counters that might be 32 bits wide. 

The Intel guys have some *very* fast timers flying around their cpu’s. They 
would laugh
at the idea of a 10 or 100 MHz clock. If you can configure the pin to grab the 
data off those timer, you
have way better than 100 ns at the timer. The trick is writing a driver that 
does that. How 
easy that is to do depends a *lot* on your OS and the chipset you are running. 
It may 
be trivial or it may be impossible.

At some point one might ask: Is a $1 MCU a “system” or is it a peripheral? 

Bob


> On Feb 17, 2017, at 5:58 PM, Thomas Petig <tho...@petig.eu> wrote:
> 
> Hi,
> 
> I was wondering whether there is some data/information available on the
> claimed +/- 100 ns jitter?
> 
> Regarding the PPS -> USB (using the CTS line of a FTDI FT232R), I
> plotted, using some lines of Python, the time offset as attached. Just
> to get an overview how it is 'worst case', i.e., user program, python,
> etc. The 1PPS signal comes from a GPS rx.
> Looks like a standard deviation of around 150 us.
> y-axis:  measured pps offset from full second (computer time) in us,
> x-axis pps pulse number.
> 
> On the long term it looks interesting (while measuring I played with the
> NTP server on this computer)
> Until ca. second 1: ntpd synchronization via internet
> Until ca. second 17000: made an additional LAN NTP server (GPS) available
> Until the end: replaced ntpd with chrony (still using internet and local
> servers)
> 
> Interesting points:
> -It looks surprisingly bad with using the normal ntpd (especially, there
> is not really an improvement having an local GPS based server
> available, did I do something wrong? Only the offset changes by ca. 3
> ms.)
> -It looks surprisingly good with chrony. But there are continuously
> outliers of up to 4500 us, is this a result of the chrony control loop?
> The time is wandering around with ntpd, but has less jitter.
> 
> Conclusion:
> Despite the 150 us stddev, the using PPS over USB gives some interesting
> inside of what the local ntp server is actually doing. It looks to me
> like it would be an improvement to use it when using ntpd, but not when
> using chrony.
> 
> Best regards,
>   Thomas
>   DK6KD
>   SA6CID
> 
> PS:
> Raw data is here, if you want to zoom in: (1.7 MiB, one row per PPS
> offset in us)
> http://petig.eu/pps-usb.txt
> 
> On Tue, Feb 14, 2017 at 07:26:23AM -0500, Bob Camp wrote:
>> Hi
>> 
>> A direct port might be a +/- 100 ns sort of thing most of the time and a 
>> +/-10 us
>> thing every so often under some OS’s. Most desktop operating systems are not
>> designed to prioritize random pin interrupts. A dirt cheap MCU coded with a 
>> few
>> (hundred) lines of assembly code may be a better option than a typical 
>> desktop.
>> Complicating this further is the degree to which some OS’s can be directly or
>> indirectly optimized. Install *this* package and it all goes nuts. Install 
>> that package
>> and not much happens ….
>> 
>> Bob
>> 
>>> On Feb 13, 2017, at 11:07 AM, Ruslan Nabioullin <rnabioul...@gmail.com> 
>>> wrote:
>>> 
>>> Hi, generally speaking, what are the performance differences between the 
>>> following: 1. direct RS-232 (i.e., what I believe is a standard PCI card 
>>> offering RS-232---essentially UARTs interfaced more-or-less directly to the 
>>> PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also 
>>> have an IRIG input or even an onboard GNSS receiver).
>>> 
>>> Thanks in advance,
>>> Ruslan
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Problems with CHU

[Bob Camp]

Hi

Not quite sure what happened to the original message before it got here …

The voice / time announcements on WWV and CHU date back quite a ways. I wonder 
just
how old the gear they currently are using is? Once upon a time it was done with 
a 
mechanical marvel of a device. 

Bob


> On Feb 16, 2017, at 12:52 PM, jmfra...@cox.net wrote:
> 
> I meant to type 7.850 MHz, re-engaged brain. 
> 
> John WA4WDL
> 
>  jmfra...@cox.net wrote: 
>> 
>> I do not know if anyone has noticed, but since sometime before 17:00 UTC, 
>> the voice announcements on the 7.8350 kHz signal have been messed up. Some 
>> times they are missing, other times they are incorrect. I have not checked 
>> the other frequencies. I was working in my workshop and switched to CHU to 
>> stay aware of the time and noticed the discrepancies. 
>> 
>> John  WA4WDL
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

Whatever you do on the server, the same impacts will be felt on the client 
side. You may be
able to do this or that on a server to allocate resources. On a client 
workstation, resource
allocation is likely to be a bit more difficult. You may not even have control 
over which 
OS is being used. ( = other factors may dictate it’s Windows 10, or OS-X or …). 
When a 
big video processing blob comes along, the workstation likely ignores NTP for a 
while. 

Bob


> On Feb 16, 2017, at 7:05 AM, Mike Cook  wrote:
> 
> 
>> Le 16 févr. 2017 à 04:09, MLewis  a écrit :
>> 
>> On 15/02/2017 1:17 PM, Chris Albertson wrote:
>>> Why set up a dedicated NTP server if you only have two computers that will 
>>> use it? ... You could save some money and just run NTP on the two 
>>> computers. ... NTP is almost zero load on the CPU and the best thing is the 
>>> NTP accuracy is not effected by CPU load…
> 
> This is not strictly true in all scenarios as the NTP thread has to be able 
> to get to a cpu to be able to do its thing. Higher priority, or CPU intensive 
> threads can starve it.
> 
> Here is the result of a little test on a 700MHz clocked 4 core uP running 
> linux with usual utilities NTP, cron whatever, but no apps . No priority or 
> core dedication implemented. 
> The uP is running NTP with two GPS sync’d servers at stratum 1  on the LAN 
> plus  5 stratum 2 pool servers. poll time 64 secs for all.
> 
> 1. Check the clock offset of the DUT as reported by ntpdate -d with the DUT 
> idle.
> mike@muon /usr/home/mike $ ntpdate -d rasp3b1 2> /dev/null | grep adjust
> 16 Feb 11:17:46 ntpdate[11566]: adjust time server 192.168.1.157 offset 
> -0.86 sec
> 16 Feb 11:19:32 ntpdate[11569]: adjust time server 192.168.1.157 offset 
> -0.85 sec
> 16 Feb 11:21:18 ntpdate[11587]: adjust time server 192.168.1.157 offset 
> -0.82 sec
> 16 Feb 11:23:05 ntpdate[11590]: adjust time server 192.168.1.157 offset 
> -0.54 sec
> 16 Feb 11:24:51 ntpdate[11593]: adjust time server 192.168.1.157 offset 
> -0.28 sec
> 16 Feb 11:26:37 ntpdate[11611]: adjust time server 192.168.1.157 offset 
> 0.08 sec
> 16 Feb 11:28:24 ntpdate[11614]: adjust time server 192.168.1.157 offset 
> 0.26 sec
> 16 Feb 11:30:10 ntpdate[11632]: adjust time server 192.168.1.157 offset 
> 0.59 sec
> 2. Start up 4 cpu soaker threads - in this case calculating pi to 1 
> places.
>  11:31:00 4 cpu soakers started on rasp3b1
> 3. Continue checking clock offsets.
> 16 Feb 11:33:42 ntpdate[11638]: adjust time server 192.168.1.157 offset 
> -0.89 sec
> 16 Feb 11:35:29 ntpdate[11656]: adjust time server 192.168.1.157 offset 
> -0.000235 sec
> 16 Feb 11:37:15 ntpdate[11659]: adjust time server 192.168.1.157 offset 
> -0.000393 sec
> 16 Feb 11:39:01 ntpdate[11662]: adjust time server 192.168.1.157 offset 
> -0.000512 sec
> 16 Feb 11:40:48 ntpdate[11680]: adjust time server 192.168.1.157 offset 
> -0.000547 sec
> 16 Feb 11:42:34 ntpdate[11683]: adjust time server 192.168.1.157 offset 
> -0.000492 sec
> 16 Feb 11:44:20 ntpdate[11686]: adjust time server 192.168.1.157 offset 
> -0.000438 sec
> 16 Feb 11:46:07 ntpdate[11704]: adjust time server 192.168.1.157 offset 
> -0.000397 sec
> 16 Feb 11:47:53 ntpdate[11709]: adjust time server 192.168.1.157 offset 
> -0.000393 sec
> 16 Feb 11:49:39 ntpdate[11712]: adjust time server 192.168.1.157 offset 
> -0.000357 sec
> 16 Feb 11:51:26 ntpdate[11730]: adjust time server 192.168.1.157 offset 
> -0.000206 sec
> 
> As you can see the reported clock offset increases to a max 0,5ms due to the 
> load on the DUT. That is within the OPs limit so he should be ok but for 
> others that may be too much of a hit.
> 
> 4. wait till the processes stop
>They all ended normally at Thu 16 Feb 12:04:36 UTC 2017
> 5. While continuing to check the offsets as reported by ntpdate
> 16 Feb 12:00:17 ntpdate[11775]: adjust time server 192.168.1.157 offset 
> 0.000153 sec
> 16 Feb 12:02:03 ntpdate[11778]: adjust time server 192.168.1.157 offset 
> 0.000188 sec
> 16 Feb 12:03:50 ntpdate[11781]: adjust time server 192.168.1.157 offset 
> 0.000203 sec
> 16 Feb 12:05:36 ntpdate[11799]: adjust time server 192.168.1.157 offset 
> 0.000126 sec
> 16 Feb 12:07:22 ntpdate[11802]: adjust time server 192.168.1.157 offset 
> 0.92 sec
> 16 Feb 12:09:09 ntpdate[11805]: adjust time server 192.168.1.157 offset 
> 0.96 sec
> 16 Feb 12:10:55 ntpdate[11823]: adjust time server 192.168.1.157 offset 
> 0.51 sec
> 16 Feb 12:12:41 ntpdate[11826]: adjust time server 192.168.1.157 offset 
> 0.08 sec
> 16 Feb 12:14:28 ntpdate[11829]: adjust time server 192.168.1.157 offset 
> 0.02 sec
> 16 Feb 12:16:14 ntpdate[11847]: adjust time server 192.168.1.157 offset 
> -0.16 sec
> 16 Feb 12:18:00 ntpdate[11852]: adjust time server 192.168.1.157 offset 
> 0.07 sec
> 16 Feb 12:19:46 ntpdate[11855]: adjust time server 192.168.1.157 offset 
> 0.09 sec
> 16 Feb 12:21:33 ntpdate[11873]: 

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi


> On Feb 16, 2017, at 1:30 AM, Ruslan Nabioullin  wrote:
> 
> On 02/15/2017 01:17 PM, Chris Albertson wrote:
>> Why set up a dedicated NTP server if you only have two computers
>> that will use it?Your server will be accurate to a few
>> microseconds but your two computers will only by good to a few
>> milliseconds because ethernet is not nearly as good as PPS.
> 
> Well Ethernet can be *extremely* accurate if PTP is used (a whitepaper 
> specifies <= 100 ns accuracy if the LAN is optimized for it).

PTP single shot over ethernet is not at the < 100 ns level, even with proper 
cards. In real world settings, the traffic level for sub
100 ns PTP can be pretty high. Some situations appear to require > 100K 
transactions per second. I’ve never seen anything quite that
extreme myself. 

Bob


> 
> Well, the assumption here is that one would render this service available to 
> the public, registering the server(s) with the NTP website and/or the NTP 
> Pool Project; n.b. this is still possible for connections lacking a static IP 
> address, by means of an IPv6 tunnel, available at no cost from at least one 
> vendor.  Otherwise yes, by some perspectives it can be considered quite 
> pointless and wasteful to operate dedicated servers, standards, receivers, 
> etc. with no means of time transfer to customers.
> 
> > NTP is almost zero load on the CPU and the best thing is the NTP
> > accuracy is not effected by CPU load  SO you can run other service
> > without degrading the NTP server.
> 
> Well n.b. TVB's hardware PPS timestamping post.  Also WWV and CHU decoding by 
> NTP's modules can be problematic, as well as the obvious case of the server 
> being overloaded.  Finally note that based on others' experimentation, the 
> motherboard's XO temperature is nontrivially-highly correlated with CPU load, 
> so for better motherboard XO-based holdover performance, once must create an 
> ersatz oven utilizing the CPU(s), by running them at full utilization 
> (obviously with proper scheduling priority), so typically volunteer 
> distributed computing project(s) such as BOINC (SETI@home, etc.), 
> Folding@Home, etc.  Of course then power consumption becomes problematic.
> 
> -Ruslan
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

Silly Canadians :)

It seems that the term either has drifted a bit over the last 70 years or there 
is indeed 
another British / US difference here. 

Bob

> On Feb 15, 2017, at 5:00 PM, iovane--- via time-nuts  
> wrote:
> 
> This Canadian RCA apparatus was also called wavemeter but is a heterodyne 
> frequency meter and a signal generator.
> 
> https://www.pa3esy.nl/military/us/meet/TE149/html/te149_set-gb.html 
> 
> iov
> 
> 
>> Messaggio originale
>> Da: "Tim Shoppa" 
>> Data: 15/02/2017 17.29
>> A: "Discussion of precise time and frequency measurement"
>> Ogg: Re: [time-nuts] Vintage Frequency Measurement
>> 
>> For those of us who have to translate between the old "cps" and the modern
>> "Hz", I found this handy conversion table on the web:
>> http://www.aqua-calc.com/convert/frequency/hertz-to-cycle-per-second
>> 
>> Tim N3QE
>> 
>> [image: Inline image 1]
>> 
>> On Tue, Feb 14, 2017 at 5:29 AM, Peter Vince 
>> wrote:
>> 
>>> On 14 February 2017 at 04:23, Raj  wrote:
>>> 
 I have a Marconi T.F. 643 C, in Megacycles !
 
>>> 
>>> Ah, a sensible, descriptive name for the unit.  Some of these modern units
>>> really do Hert(z) :-)
>>> 
>>> Peter
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

The link gives an error, but I have no doubt that the meaning of the term 
varies a bit. 
Thanks for the reference. I’ll try to get it working from here. 

Bob

> On Feb 15, 2017, at 2:28 AM, Robert Atkinson via time-nuts 
> <time-nuts@febo.com> wrote:
> 
> Hi,Sorry if I caused confusion by calling the SCR/BC221 a wavemeter. Clearly 
> it's not in the wider usage of the term, and the manual and front panel call 
> it a frequency meter. However the similar British device was called a 
> wavemeter "Wavemeter Class D" 
> http://www.vmarsmanuals.co.uk/archive/724_Wavemeter_Class_D_No2_Working_Instructions.pdfSo
>  here in the UK the 221 was often also called a wavemeter. Classic wavemeters 
> were also available for example the Marconi TF975.
> Robert G8RPI.
> 
>  From: Bob Camp <kb...@n1k.org>
> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> 
> Sent: Monday, 13 February 2017, 23:46
> Subject: Re: [time-nuts] Vintage Frequency Measurement
> 
> Hi
> 
> With a VFO running, you have a heterodyne frequency meter. That is (at least 
> to me)
> a very different device than an absorption wave meter. I know way to put 
> power into
> a BC-221 and use it as an absorption device. 
> 
> I’m not in any way saying that the LM or the 221 are less useful. They are 
> still to this day
> great little boxes. The just aren’t (by my understanding) wave meters. That 
> term describes
> a different device that works a different way. 
> 
> Bob
> 
>> On Feb 13, 2017, at 5:52 PM, John Miles <j...@miles.io> wrote:
>> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi


> On Feb 14, 2017, at 9:23 PM, Chris Albertson  
> wrote:
> 
> On Tue, Feb 14, 2017 at 7:31 AM, MLewis  wrote:
> 
>> 
>> 
>> - a dedicated machine/box for unencumbered acceptance of PPS, and
>> - for systems with a business need, a dedicated NTP server/box disciplined
>> by the PPS source (with dedicated communication), while maintaining
>> internet NTP sources as backup for when the PPS source fails?
>> Is there a better way?
>> Other considerations?
> 
> 
> Don't ever think about "backup servers".  NTP will always select the "best"
> reference clocks.   The best ones are defined as the subset of references
> that track each other.
> 
> Best practice today is to have two independent NTP servers and two GPS
> receivers.  

I would argue that you need at least three servers (and more like five). When 
given only two 
servers NTP simply dithers back and forth between them. It does not have 
a way to figure out which of two clocks is wrong. It will detect a missing 
clock, but 
not one that is simply off time by a bit.

Bob


> It is best if these are independent as you can make them,
> different buildings if you can.   I would even use different brands of
> hardware to protect against a bug.   Then throughout your company all your
> PCs are configured to look at both NTP servers
> 
> Each server is configured to use the GPS reference clock, the other "twin"
> NTP server as well as about five Internet "pool" servers.
> 
> If your location does not have an Internet connection. ( YES this can
> happen.  I've worked on computers that process classified information and
> these computers never have Internet access.)  You can configure them so
> they run in "orphan mode" that is they all use each other as reference
> clocks.  Then when GPS is lost thenoormal NTP clock selection algorithm
> will select the subset of PCs that all agree on what the time is.   The
> outliers tent to get ignored.When GPS comes back up the system makes a
> gradual and graceful recovery.
> 
> 
> 
> 
> 
> Chris Albertson
> Redondo Beach, California
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

If you want a 1588 PHY and are on a budget:

https://www.digikey.com/products/en/development-boards-kits-programmers/evaluation-boards-embedded-mcu-dsp/786?k=freescale+freedom==freescale+freedom=24619=ffe00312%2C7e80098=0=0=0=1=0=0=0=25

Drop NTP into it and let it rip.

Bob


> On Feb 14, 2017, at 5:26 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> 
> Something like this would make a great NTP server.
> https://www.digikey.com/products/en?keywords=P0286-ND
> 
> Too bad they didn't include a PTP 1588 capable PHY...
> 
> On Tue, Feb 14, 2017 at 12:33 PM, Chris Albertson <albertson.ch...@gmail.com
>> wrote:
> 
>> Here is a something that could work.  It has a real serial port and you
>> could add more ethernet controllers, uses very little power and cost only
>> $60.
>> www.newegg.com/
>> <https://www.newegg.com/Product/Product.aspx?Item=
>> N82E16813157497_re=j1900-_-13-157-497-_-Product>
>> 
>> There are other boards like this that use the same J1900 CPU.   I'm
>> thinking about using this as th machine tool (milling machine) controller.
>> 
>> On Tue, Feb 14, 2017 at 4:26 AM, Bob Camp <kb...@n1k.org> wrote:
>> 
>>> Hi
>>> 
>>> A direct port might be a +/- 100 ns sort of thing most of the time and a
>>> +/-10 us
>>> thing every so often under some OS’s. Most desktop operating systems are
>>> not
>>> designed to prioritize random pin interrupts. A dirt cheap MCU coded with
>>> a few
>>> (hundred) lines of assembly code may be a better option than a typical
>>> desktop.
>>> Complicating this further is the degree to which some OS’s can be
>> directly
>>> or
>>> indirectly optimized. Install *this* package and it all goes nuts.
>> Install
>>> that package
>>> and not much happens ….
>>> 
>>> Bob
>>> 
>>>> On Feb 13, 2017, at 11:07 AM, Ruslan Nabioullin <rnabioul...@gmail.com
>>> 
>>> wrote:
>>>> 
>>>> Hi, generally speaking, what are the performance differences between
>> the
>>> following: 1. direct RS-232 (i.e., what I believe is a standard PCI card
>>> offering RS-232---essentially UARTs interfaced more-or-less directly to
>> the
>>> PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also
>>> have an IRIG input or even an onboard GNSS receiver).
>>>> 
>>>> Thanks in advance,
>>>> Ruslan
>>>> ___
>>>> time-nuts mailing list -- time-nuts@febo.com
>>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>>> mailman/listinfo/time-nuts
>>>> and follow the instructions there.
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>> 
>> 
>> 
>> --
>> 
>> Chris Albertson
>> Redondo Beach, California
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

HI

What frequency is the crystal and what sized package is it in? 

Bob

> On Feb 14, 2017, at 11:20 AM, Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> 
> Taking a second look in the manual, they specifically call out that its not
> an AT or BT, so I'm not sure what it would be.
> 
> Interestingly they describe the thermometer as space-saving and trouble
> free alternative to a heater and thermostat apparatus (I guess they weren't
> called ovens yet?)
> 
> On Mon, Feb 13, 2017 at 10:11 PM, Bob Camp <kb...@n1k.org> wrote:
> 
>> Hi
>> 
>> 
>>> On Feb 13, 2017, at 8:15 PM, Scott Stobbe <scott.j.sto...@gmail.com>
>> wrote:
>>> 
>>> On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp <kb...@n1k.org> wrote:
>>> 
>>>> 
>>>> 
>>>> I think what you would find is that it *is* a fairly normal AT cut and
>> the
>>>> data book
>>>> that came with the instrument plotted out the data for the specific
>>>> crystal in
>>>> the device. The usable temperature range was fairly small, so the plot
>> will
>>>> be pretty linear.
>>>> 
>>> 
>>> Attached is a plot of crystal calibrators temperature stability. Span is
>>> roughly 65 degC.
>> 
>> Which eyeballs out to be pretty close to an AT. Without knowing the PPM
>> scale there isn’t much way to be sure.
>> 
>>> 
>>> One of the other aspects I think is intriguing is the DC PSRR of a vacuum
>>> tube crystal oscillator. In the case of a bjt based oscillator you have
>> the
>>> C-V relation for depletion capacitance and the base-emitter dynamic
>>> capacitance as a function of collector current. I would suspect that for
>> a
>>> one active device oscillator, tube vs bjt, a tube crystal oscillator
>> would
>>> be less sensitive to small power supply variations (+- 10% ).
>> 
>> Except you *do* have miller effect which pretty much messes things up
>> for a triode. A pentode is a bit less sensitive, but you still have issues.
>> 
>>> Which is a
>>> convenient attribute for a poorly/unregulated battery supply in the
>> vacuum
>>> tube case. Unless filament current has an appreciable impact on
>> frequency,
>>> I wouldn't think so…
>> 
>> Umm… e …. check it out :)
>> Oddly enough, I remember a high school physics lab where they had us plot
>> the effect of filament voltage on plate current and gain. Seemed like a
>> weird
>> thing to do to me at the time. Turns out the teacher grew up with
>> microwave tubes
>> that were tuned by varying the filament. Who knew ???  Pretty strange
>> stuff if
>> you ask me.
>> 
>> The bigger issue is the tubes get hot. The heat varies with supply voltage.
>> Temperature change is the result. That temperature change messes up
>> oscillator stability. You pretty much have to wait for things to hit
>> equilibrium
>> before you do useful stuff ( = let it warm up for an hour or four).
>> 
>> Bob
>> 
>> 
>> 
>>> __
>> _
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/
>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

> On Feb 14, 2017, at 10:31 AM, MLewis <mlewis...@rogers.com> wrote:
> 
> 
> 
> On 14/02/2017 7:26 AM, Bob Camp wrote:
>> Hi
>> 
>> A direct port might be a +/- 100 ns sort of thing most of the time and a 
>> +/-10 us
>> thing every so often under some OS’s. Most desktop operating systems are not
>> designed to prioritize random pin interrupts. A dirt cheap MCU coded with a 
>> few
>> (hundred) lines of assembly code may be a better option than a typical 
>> desktop.
>> Complicating this further is the degree to which some OS’s can be directly or
>> indirectly optimized. Install *this* package and it all goes nuts. Install 
>> that package
>>  and not much happens ….
>> 
>> Bob
>> 
> Hence, wouldn't Best Practice be boxes loaded with only the bare OS and 
> software for the time-related tasks?

That would be one approach.

> As in:
> - a dedicated machine/box for unencumbered acceptance of PPS, and
> - for systems with a business need, a dedicated NTP server/box disciplined by 
> the PPS source (with dedicated communication), while maintaining internet NTP 
> sources as backup for when the PPS source fails?
> Is there a better way?

It depends on what you are trying to do. If the objective is to replace a piece 
of test gear
logging 100% of your events at the 100ns level, the computer likely will not 
measure up. If the objective is to run
NTP at the 100 us level, there are a lot more things you can get away with. NTP 
is designed from the 
ground up to be quite tolerant of various issues. 

Bob

> Other considerations?
> 
> Michael
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

That was one of the reasons I was a bit amazed high school students
were doing it as a lab exercise. The presence of high voltage here and 
there is something that you simply would not see in a similar school
today …

Bob

> On Feb 13, 2017, at 11:19 PM, Alex Pummer <a...@pcscons.com> wrote:
> 
> just be careful, because if you under-heat the cathode you could kill it
> 
> 73
> 
> Alex
> 
> 
> On 2/13/2017 7:11 PM, Bob Camp wrote:
>> Hi
>> 
>> 
>>> On Feb 13, 2017, at 8:15 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote:
>>> 
>>> On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp <kb...@n1k.org> wrote:
>>> 
>>>> 
>>>> I think what you would find is that it *is* a fairly normal AT cut and the
>>>> data book
>>>> that came with the instrument plotted out the data for the specific
>>>> crystal in
>>>> the device. The usable temperature range was fairly small, so the plot will
>>>> be pretty linear.
>>>> 
>>> Attached is a plot of crystal calibrators temperature stability. Span is
>>> roughly 65 degC.
>> Which eyeballs out to be pretty close to an AT. Without knowing the PPM
>> scale there isn’t much way to be sure.
>> 
>>> One of the other aspects I think is intriguing is the DC PSRR of a vacuum
>>> tube crystal oscillator. In the case of a bjt based oscillator you have the
>>> C-V relation for depletion capacitance and the base-emitter dynamic
>>> capacitance as a function of collector current. I would suspect that for a
>>> one active device oscillator, tube vs bjt, a tube crystal oscillator would
>>> be less sensitive to small power supply variations (+- 10% ).
>> Except you *do* have miller effect which pretty much messes things up
>> for a triode. A pentode is a bit less sensitive, but you still have issues.
>> 
>>> Which is a
>>> convenient attribute for a poorly/unregulated battery supply in the vacuum
>>> tube case. Unless filament current has an appreciable impact on frequency,
>>> I wouldn't think so…
>> Umm… e …. check it out :)
>> Oddly enough, I remember a high school physics lab where they had us plot
>> the effect of filament voltage on plate current and gain. Seemed like a weird
>> thing to do to me at the time. Turns out the teacher grew up with microwave 
>> tubes
>> that were tuned by varying the filament. Who knew ???  Pretty strange stuff 
>> if
>> you ask me.
>> 
>> The bigger issue is the tubes get hot. The heat varies with supply voltage.
>> Temperature change is the result. That temperature change messes up
>> oscillator stability. You pretty much have to wait for things to hit 
>> equilibrium
>> before you do useful stuff ( = let it warm up for an hour or four).
>> 
>> Bob
>> 
>> 
>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to 
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
>> 
>> -
>> No virus found in this message.
>> Checked by AVG - www.avg.com
>> Version: 2016.0.7998 / Virus Database: 4756/13950 - Release Date: 02/13/17
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] ``direct'' RS-232 vs. RS-232 via USB vs. PPS decoding cards

[Bob Camp]

Hi

A direct port might be a +/- 100 ns sort of thing most of the time and a +/-10 
us 
thing every so often under some OS’s. Most desktop operating systems are not
designed to prioritize random pin interrupts. A dirt cheap MCU coded with a few
(hundred) lines of assembly code may be a better option than a typical desktop. 
Complicating this further is the degree to which some OS’s can be directly or
indirectly optimized. Install *this* package and it all goes nuts. Install that 
package
 and not much happens ….

Bob

> On Feb 13, 2017, at 11:07 AM, Ruslan Nabioullin  wrote:
> 
> Hi, generally speaking, what are the performance differences between the 
> following: 1. direct RS-232 (i.e., what I believe is a standard PCI card 
> offering RS-232---essentially UARTs interfaced more-or-less directly to the 
> PCI bus); 2. RS-232 via USB; 3. PPS decoding PCI cards (which might also have 
> an IRIG input or even an onboard GNSS receiver).
> 
> Thanks in advance,
> Ruslan
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi


> On Feb 13, 2017, at 8:15 PM, Scott Stobbe <scott.j.sto...@gmail.com> wrote:
> 
> On Mon, Feb 13, 2017 at 6:41 PM, Bob Camp <kb...@n1k.org> wrote:
> 
>> 
>> 
>> I think what you would find is that it *is* a fairly normal AT cut and the
>> data book
>> that came with the instrument plotted out the data for the specific
>> crystal in
>> the device. The usable temperature range was fairly small, so the plot will
>> be pretty linear.
>> 
> 
> Attached is a plot of crystal calibrators temperature stability. Span is
> roughly 65 degC.

Which eyeballs out to be pretty close to an AT. Without knowing the PPM 
scale there isn’t much way to be sure. 

> 
> One of the other aspects I think is intriguing is the DC PSRR of a vacuum
> tube crystal oscillator. In the case of a bjt based oscillator you have the
> C-V relation for depletion capacitance and the base-emitter dynamic
> capacitance as a function of collector current. I would suspect that for a
> one active device oscillator, tube vs bjt, a tube crystal oscillator would
> be less sensitive to small power supply variations (+- 10% ).

Except you *do* have miller effect which pretty much messes things up
for a triode. A pentode is a bit less sensitive, but you still have issues.

> Which is a
> convenient attribute for a poorly/unregulated battery supply in the vacuum
> tube case. Unless filament current has an appreciable impact on frequency,
> I wouldn't think so…

Umm… e …. check it out :)
Oddly enough, I remember a high school physics lab where they had us plot
the effect of filament voltage on plate current and gain. Seemed like a weird
thing to do to me at the time. Turns out the teacher grew up with microwave 
tubes
that were tuned by varying the filament. Who knew ???  Pretty strange stuff if 
you ask me. 

The bigger issue is the tubes get hot. The heat varies with supply voltage. 
Temperature change is the result. That temperature change messes up 
oscillator stability. You pretty much have to wait for things to hit 
equilibrium 
before you do useful stuff ( = let it warm up for an hour or four).

Bob



> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi


> On Feb 13, 2017, at 10:35 AM, Scott Stobbe  wrote:
> 
> Hi Mike,
> 
> First of all, Wow what an interesting read, thanks for sharing some of the
> history and your experiences with the 105. A second thanks for uploading
> the manual, which I found to be a great read, as with most old test &
> measurement product manuals, they are far from just marketing fluff.
> 
> Bare with me, I'm not well versed in early radio history, but, I also found
> it neat they choose to crystal calibrate on the 3rd harmonic of the VFO to
> help prevent injection lock and for increased sensitivity (but that may be
> true of all frequency meters of the era, don't know).
> 
> Based on the manual, the thermometer is thermally mounted to crystal
> holder, allowing one to temperature compensate the crystal calibration
> point. I didn't see a mention as to what crystal cut they used. I would
> guess it is one with a flat tempCo with no turning points for the linear
> thermometer scale to be used effectively.

I think what you would find is that it *is* a fairly normal AT cut and the data 
book 
that came with the instrument plotted out the data for the specific crystal in 
the device. The usable temperature range was fairly small, so the plot will
be pretty linear.

Bob

> 
> Attached is a plot taken from the manual, the VFO stability strip-chart
> 
> On Mon, Feb 13, 2017 at 12:24 AM, Mike Naruta AA8K  wrote:
> 
>> 
>> On 02/12/2017 01:08 AM, Scott Stobbe wrote:
>> 
>>> I was inspired recently coming across a Lampkin 105 frequency meter, as to
>>> how  frequency measurement was done before counters.
>>> 
>>> Certainly zero-beating a dial calibrated oscillator, would be one
>>> approach.
>>> 
>>> Is there a standout methodology or instrument predating counters?
>>> 
>>> 
>> Hi Scott.  That Lampkin 105 is a sophisticated design.  I did some
>> research that you might be interested:
>> 
>> For the 2015 November ARRL Frequency Measuring Test, I fired up my old
>> Lampkin frequency meter.  For their 100th Anniversary, QST was encouraging
>> the use of “vintage” equipment for the FMT, and the Lampkin was designed in
>> the 1930s.
>> 
>> I (AA8K) did surprisingly well, coming within 322 Hertz on 40 meters, 202
>> Hertz on 80 meters, and 18 Hertz on 160 meters.
>> 
>> The Lampkin 105-B was designed by Guy Forest Lampkin BSEE, who got his
>> first ham license in 1924.  In 1933 he was selling the model 102, that was
>> checked with the Federal Radio Commission and commercial laboratories to be
>> within 3 to 15 cycles at 1,712 kc.  He was also selling a “foundation unit”
>> of the Precision Micrometer, Band Spread condenser, Special Isolantite coil
>> form, Temperature compensator, Adjustable pad condenser, and complete
>> circuit details for $14.50.  Lampkin Laboratories moved from 146 West
>> McMillian Street, Cincinnati, Ohio to 8400 Ninth Avenue N.W., Bradenton,
>> Florida 33506 in 1935.  It was incorporated in 1942.  Precise Power
>> Corporation had acquired Lampkin Laboratories in 1971/Oct.  At that time
>> Lampkin Labs had 17 employees and wasn't advertising their 107B Digital
>> Frequency Meter because they were selling as fast as they could make them.
>> The last known address was 12297 US Highway 41 North, Palmetto, Florida
>> 34221.  Voluntary Dissolution 2007/April/27.
>> 
>> The 105-B is a fascinating design, able to measure frequency to 0.0025%.
>> Signals can be measured from 100 KHz to 175 MHz.   It works similarly to
>> the later World War II BC-221 frequency meter.  It can receive, or transmit
>> the internal oscillator 2330-2670 KHz.  A diode generates harmonics that
>> can beat against the signal to be measured.
>> 
>> The variable condenser has a precision-machined tubular stator and a
>> tapered, conical rotor.  They are made from steel and brass and copper
>> plated.  The parts are proportioned such that, due to the differential
>> thermal expansion, the temperature coefficient of capacity is a few parts
>> per million per degree Celsius at all positions of the rotor.  The rotor is
>> moved in and out of the stator on a micrometer screw.  The large dial and
>> turns counter give a dial band spread of 8,000 divisions over 42 feet!  The
>> inductor is wound on a six-ribbed form of polystyrene.  Since the thermal
>> expansion of polystyrene is greater than copper, as coil temperature
>> increases, the turns are pulled from circular to hexagonal, and the average
>> diameter of the coil decreases.
>> 
>> Thermal design is utmost in the Lampkin MFM.  In addition to the L/C
>> circuit, the vacuum tubes and circuitry are mounted on the rear, with the
>> chassis cut-away to keep it from heating the front where the L/C and
>> calibration crystal are mounted.  Wires connecting the L/C and crystal are
>> very small diameter to reduce the thermal path.  Even the power transformer
>> is bolted to the outside of the cabinet.  The 7.5 MHz calibration crystal
>> (no oven) is held against 

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

With a VFO running, you have a heterodyne frequency meter. That is (at least to 
me)
a very different device than an absorption wave meter. I know way to put power 
into
a BC-221 and use it as an absorption device. 

I’m not in any way saying that the LM or the 221 are less useful. They are 
still to this day
great little boxes. The just aren’t (by my understanding) wave meters. That 
term describes
a different device that works a different way. 

Bob

> On Feb 13, 2017, at 5:52 PM, John Miles  wrote:
> 
> You could use it as an absorption wavemeter, in its broadest sense of a 
> passive tuned circuit with an indicating load.  The headphone jack was 
> normally used to calibrate the VFO against a harmonic of the internal crystal 
> oscillator, but it could zero beat an external source as well.  It stretches 
> the nomenclature but the job still gets done.
> 
> Even as late as the 1980s a BC-221 (or LM-10 in my case) was a useful piece 
> of gear.  As Bill suggests, all the qualities needed for indulgence in 
> time/frequency nuttery were present.  They were incredibly expensive to 
> build, being engineered to survive bombs that hadn't even been invented yet, 
> and they could perform at levels beyond any reasonable requirement.  I used 
> one for frequency spotting on my even-older Philco console.  
> 
> Just the other day, I visited the Spark Museum in Bellingham, WA, and was 
> amused to see one over by the 'Titanic' exhibit.  Not a curation mistake on 
> their part, just a consequence of having more cool stuff than exhibit space.  
> I had to restrain myself from reaching down and giving the dial a tweak.
> 
> -- john, KE5FX
> Miles Design LLC
> 
>> Hi Bob:
>> 
>> The BC-221 is usually referred to as either a Frequency Meter or a
>> Heterodyne Frequency Meter.
>> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

Ok, so how does that make a BC-221 a wave meter?

Bob

> On Feb 12, 2017, at 7:15 PM, Wes <w...@triconet.org> wrote:
> 
> On 2/12/2017 12:51 PM, Bob Camp wrote:
>> Hi
>> 
>> Maybe I’ve been wrong for the last many decades …
>> 
>> To me a wave meter is a tuned circuit device that tells you the frequency by 
>> a resonance
>> peak. They are a very common old school item for microwave frequency 
>> measurement in
>> a teaching setting.
>> 
>> https://www.britannica.com/technology/wavemeter
>> 
>> Bob
>> 
> As I said before, there were cavity wavemeters used in industry. I've 
> attached a couple of pictures that show some in action.  In both photos I 
> (with the tie) and my partner are working on a prototype IMPATT diode power 
> amplifier for the AIM-54C Phoenix Missile.  This used 16 matched IMPATT 
> diodes in an X-band cavity. At this point it is actually a free-running, 
> pulsed oscillator.  In the final usage it was injection locked to a three 
> diode oscillator which in turn was driven by a single diode that was locked 
> to a GUNN oscillator. These were all connected via a five-port circulator. 
> The GUNN was phase locked to VCXOs at about 100 MHz, multiplied 96 times to 
> X-Band.
> 
> Since this was free-running the frequency measurement accuracy of a cavity 
> wavemeter was adequate.  In photo 2 the wavemeter is the grey cylinder with 
> the black top just in front of the lab notebook.  In operation it was tuned 
> and caused an amplitude notch that was detected with a waveguide-mounted 
> diode.
> 
> In the other photo there is another wavemeter on the test station behind me 
> among some waveguide attenuators and phase shifters. Maybe of interest to 
> frequency nuts is the transmitter-receiver unit from the production AIM-54A 
> missile.  It is just "above" the bend of my elbow. There were seven, pie 
> shaped VCXO circuit cards in a temperature-controlled chassis.  Maintaining 
> frequency accuracy under launch shock and the vibration from hanging on the 
> wing of an F14 at Mach 2 was lots of fun.
> 
> Wes
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

The GR is a classical wave meter that works off of a tuned circuit and a 
broadband
detector. The BC-221 works on an entirely different principle and has no 
ability at all
to run in the mode that the GR operates in.

Bob

> On Feb 12, 2017, at 9:13 PM, Alan Hochhalter  wrote:
> 
> I have a General Radio Type CAG-60098-A Precision Wave Meter made for Navy
> Department - Bureau of Ships according to the nameplate.  According to
> Wikipedia that would date it between 1940 (when bureau of ships was
> created) and 1966 (when abolished).  It has an inductor in sort of a
> "hockey puck" labeled 16-50 kc that plugs into a socket on the front panel.
> Inside is a very nicely made variable capacitor with a vernier drive.  It
> has been a while since I had it apart, but there is a diode in series with
> the meter and not much else as I recall.  The meter scale is 0-200
> (microamp?) and the capacitor scale is 0-75 with no other marking.  I have
> no manual, but I assume there were other inductors for different frequency
> ranges with a calibration chart to interpret the 0-75 reading.  It must
> have been made to test transmitters by tuning for peak reading on the meter
> and determining the frequency from the dial reading.
> 
> a different Alan (KE7AXC)
> 
> On Sun, Feb 12, 2017 at 5:47 PM, Alan Melia 
> wrote:
> 
>> Hi Dan yes that is 5e-6 about all an unstabilised (temp) AT could hold for
>> any period. I guess there were no WWV or MSF signals around then. When a
>> good source was available off-air it was possible to do better than that.
>> In service it was probably "dont waste time trying to better the minimum
>> requirement. The transmitter you are looking for wont be that accurate or
>> stable"
>> 
>> In 1960s I saw several BC-221s in the racks at the Rugby LF and HF
>> stations acting as standby frequency sources (VFO) for rapidly running up a
>> transmitter on an unusual frequency (not a normal route) for which they did
>> not have a crystal available.
>> 
>> Alan
>> G3NYK
>> - Original Message - From: "Dan Rae" 
>> To: "Discussion of precise time and frequency measurement" <
>> time-nuts@febo.com>
>> Sent: Sunday, February 12, 2017 11:11 PM
>> Subject: Re: [time-nuts] Vintage Frequency Measurement
>> 
>> 
>> To put BC-221 things in perspective, the 1 Mc/s reference crystal was
>>> adjusted, according to the manual, to within 5 c/s...
>>> 
>>> Things have come a ways since!
>>> 
>>> Dan
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>>> ailman/listinfo/time-nuts
>>> and follow the instructions there.
>>> 
>> 
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

If you look at a typical BC-221 in use, it goes from “calibrated” in a nice 
warm hut to the back 
of a jeep. It heads out to an ice cold flight line and the switch turns the 
batteries back on again.
It bumps in and out of a batch of B-17’s setting each one up for the day’s net 
frequencies. You
would be doing very well to hold 50 ppm under those circumstances. That was 
indeed adequate
for the purpose.

Bob


> On Feb 12, 2017, at 7:58 PM, Bob Albert via time-nuts  
> wrote:
> 
> Well 5 cycles per second is more than accurate enough.  That translates to a 
> 150 Hz error at 30 MHz, definitely negligible for the uses of all these gear. 
>  There was no official Time Nuts group at the time, although many of us had 
> the spirit.  Yet the capability of the BC-221 far exceeded its specification 
> if you could receive WWV.
> 
> I noted immediately that zero beat of WWV at 5 MHz was not as precise as at 
> 15 MHz.  In those days there was even a 30 MHz WWV but it got shut down a 
> long time ago.  And there were CHU and JJY.
> 
> Bob
> 
> 
>On Sunday, February 12, 2017 4:02 PM, Dan Rae  wrote:
> 
> 
> To put BC-221 things in perspective, the 1 Mc/s reference crystal was 
> adjusted, according to the manual, to within 5 c/s...
> 
> Things have come a ways since!
> 
> Dan
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

That’s not the *accuracy* of the crystal mind you. That’s how close you do the 
zero 
beat to something else that is more accurate. The crystal is out in the open 
and it
drifts quite a bit as the unit warms up or changes temperature due to being 
moved 
around. 

Bob

> On Feb 12, 2017, at 6:11 PM, Dan Rae  wrote:
> 
> To put BC-221 things in perspective, the 1 Mc/s reference crystal was 
> adjusted, according to the manual, to within 5 c/s...
> 
> Things have come a ways since!
> 
> Dan
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] how many seconds out does GPS discipline being to improve Rubidium stability?

[Bob Camp]

Hi

How an ADEV floor do you expect to see on your devices? 

How short a Tau are you after.

Depending on the answers to those questions, splitting things can be pretty 
easy 
or pretty hard. Isolating signals between multiple test sets is a bit of a pain 
if the
splitting is not done with active devices. 

The phase data used for all of your tests is identical. The test run for one is 
no 
different than the test run for any of the rest of them. The process consists 
of 
obtaining a data set and then running the appropriate statistical evaluation 
on that data. 

Bob

> On Feb 12, 2017, at 1:16 PM, gkk gb <modjkl...@comcast.net> wrote:
> 
> That is an interesting suggestion (thanks), and would indeed work for me if 
> it is possible to split the DUT signal into 3 signals in a such a way that 
> wouldn't affect measurements for ADEV, TDEV, MTIE. But I'm thinking anything 
> active would introduce it's own noise into the signal and change the data. 
> Has this technique been used to success in the past?
> 
>> On February 12, 2017 at 4:12 AM Peter Reilley <preilley_...@comcast.net> 
>> wrote:
>> 
>> 
>> Could you do all three tests in parallel?   One unit under test driving 
>> three counters.
>> Each counter using a different reference signal, one on a OCXO, one on a 
>> rubidium,
>> and one on a GPS disciplined oscillator.   At each point in time during 
>> the test simply
>> choose the one that gives the best ADEV?
>> 
>> Pete.
>> 
>> On 2/11/2017 6:52 PM, Bob Camp wrote:
>>> Hi
>>> 
>>> Using ADEV as an example (the other stuff will have it’s own curves, but 
>>> the result is the same):
>>> 
>>> A typical Rb should have a stability at short tau that goes as 1/ square 
>>> root(Tau). If you are at 2x10^-11 at 1 second, you
>>> will be at 2x10^-12 at 100 seconds and 2x10^-13 at 1,000 seconds. Somewhere 
>>> in the parts in 10^-13 that relation will
>>> start to diverge from reality.
>>> 
>>> A fairly normal low frequency OCXO has a stability that is fairly flat with 
>>> tau in the 1 to 100 second range. If they have been
>>> on power constantly that “flat zone" may extend to 1,000 seconds. Floors 
>>> should be in the low parts in 10^-12 to mid parts
>>> in 10^-13 range.
>>> 
>>> A good OCXO *may* beat a normal Rb at 1,000 seconds. That may or may not be 
>>> an issue in your case. It depends a lot
>>> on what you are trying to do.
>>> 
>>> Simple solutions:
>>> 
>>> 1) Run something better than an Rb. A hydrogen maser is one alternative 
>>> (simple if you don’t have to pay for it).
>>> 2) Do all your measurements as three corner hats. You run two references 
>>> and one DUT into gear that will do that sort of test.
>>> 3) Segment the measurements and use carefully selected references for those 
>>> ranges.
>>> 
>>> None of those are actually simple. Number 3 sounds cool until you realize 
>>> that you are switching test setups around a lot and
>>> the devices you are using still need a setup like 2 to figure out which 
>>> ones to use.
>>> 
>>> So do you need a GPS? What are the limits on your MTIE tests? (MTIE on an 
>>> OCXO is highly dependent on several
>>> things so there is no simple number there). A very normal quartz based 
>>> GPSDO might be a fine reference for your test.
>>> 
>>> How much shorter are the other tests? Is ADEV at 1,000 seconds even of 
>>> interest? If the answer is < 1,000 seconds a
>>> Rb may not do you much good at all.
>>> 
>>> Lots of twists and turns.
>>> 
>>> Bob
>>> 
>>> 
>>> 
>>> 
>>> 
>>>> On Feb 11, 2017, at 5:52 PM, gkk gb <modjkl...@comcast.net> wrote:
>>>> 
>>>> Thanks Bob,
>>>> 
>>>> 
>>>> 
>>>> I should clarify the MTIE measurement extends 10 seconds (the others 
>>>> are less time). Is it a reasonable question to ask if GPS is needed? Or 
>>>> are there other variables that are involved?
>>>> 
>>>> 
>>>> 
>>>> Good point about the temperature stability, I hadn't considered that. Can 
>>>> I place in a temperature chamber to provide a better thermal environment, 
>>>> or does that cause other issues (vibration from blowers, EMI noise, etc.)? 
>>>> Other ways to mitigate temperature changes?
>>>> 
>>>> 
>>>> 
>>>>

Re: [time-nuts] how many seconds out does GPS discipline being to improve Rubidium stability?

[Bob Camp]

Hi

You likely need to do this with something like a TimePod to get the resolution. 
Setting up 
three of them (or anything similar) is going to cost you way more than the Rb.

If you have a 100 ps counter, you will get 1x10^-10 at 1 second for ADEV data. 
That will
go to 1x10^-11 at 10 seconds and 1x10^-12 at 100 seconds. You only hit 1x10^-13 
at
1,000 seconds. Again it’s a “resolution 5X better than measurement” sort of 
thing. You
don’t want to read the floor of your test gear, you want to see the device 
under test. If
you have a 20 ps counter the numbers above would be your 5X limits rather than 
the floor. 

Again, this gets back to the “what do you want to do?” and “how short is your 
shortest tau?” 
questions. In the actual use case, there may be no interest at all in Tau’s 
shorter than 
1,000 seconds. It’s also possible that the OCXO’s have an expected floor at 
1x10^-10 from
1 second to 1,000 seconds. There are lots of variables. 

Bob

> On Feb 12, 2017, at 7:12 AM, Peter Reilley <preilley_...@comcast.net> wrote:
> 
> Could you do all three tests in parallel?   One unit under test driving three 
> counters.
> Each counter using a different reference signal, one on a OCXO, one on a 
> rubidium,
> and one on a GPS disciplined oscillator.   At each point in time during the 
> test simply
> choose the one that gives the best ADEV?
> 
> Pete.
> 
> On 2/11/2017 6:52 PM, Bob Camp wrote:
>> Hi
>> 
>> Using ADEV as an example (the other stuff will have it’s own curves, but the 
>> result is the same):
>> 
>> A typical Rb should have a stability at short tau that goes as 1/ square 
>> root(Tau). If you are at 2x10^-11 at 1 second, you
>> will be at 2x10^-12 at 100 seconds and 2x10^-13 at 1,000 seconds. Somewhere 
>> in the parts in 10^-13 that relation will
>> start to diverge from reality.
>> 
>> A fairly normal low frequency OCXO has a stability that is fairly flat with 
>> tau in the 1 to 100 second range. If they have been
>> on power constantly that “flat zone" may extend to 1,000 seconds. Floors 
>> should be in the low parts in 10^-12 to mid parts
>> in 10^-13 range.
>> 
>> A good OCXO *may* beat a normal Rb at 1,000 seconds. That may or may not be 
>> an issue in your case. It depends a lot
>> on what you are trying to do.
>> 
>> Simple solutions:
>> 
>> 1) Run something better than an Rb. A hydrogen maser is one alternative 
>> (simple if you don’t have to pay for it).
>> 2) Do all your measurements as three corner hats. You run two references and 
>> one DUT into gear that will do that sort of test.
>> 3) Segment the measurements and use carefully selected references for those 
>> ranges.
>> 
>> None of those are actually simple. Number 3 sounds cool until you realize 
>> that you are switching test setups around a lot and
>> the devices you are using still need a setup like 2 to figure out which ones 
>> to use.
>> 
>> So do you need a GPS? What are the limits on your MTIE tests? (MTIE on an 
>> OCXO is highly dependent on several
>> things so there is no simple number there). A very normal quartz based GPSDO 
>> might be a fine reference for your test.
>> 
>> How much shorter are the other tests? Is ADEV at 1,000 seconds even of 
>> interest? If the answer is < 1,000 seconds a
>> Rb may not do you much good at all.
>> 
>> Lots of twists and turns.
>> 
>> Bob
>> 
>> 
>> 
>> 
>> 
>>> On Feb 11, 2017, at 5:52 PM, gkk gb <modjkl...@comcast.net> wrote:
>>> 
>>> Thanks Bob,
>>> 
>>> 
>>> 
>>> I should clarify the MTIE measurement extends 10 seconds (the others 
>>> are less time). Is it a reasonable question to ask if GPS is needed? Or are 
>>> there other variables that are involved?
>>> 
>>> 
>>> 
>>> Good point about the temperature stability, I hadn't considered that. Can I 
>>> place in a temperature chamber to provide a better thermal environment, or 
>>> does that cause other issues (vibration from blowers, EMI noise, etc.)? 
>>> Other ways to mitigate temperature changes?
>>> 
>>> 
>>> 
>>> It seems a Rubidium is good after a timescale of 100 s. What do people do 
>>> below 100 s to characterize quartz oscillators. Do they simply try to find 
>>> the most stable parts they can afford and break the x-axis (tau) into two 
>>> regions using difference references for each? If so, are there generally 
>>> accepted "gold" standards anyone can recommend for crystal products with 
>>> the best s

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

Maybe I’ve been wrong for the last many decades … 

To me a wave meter is a tuned circuit device that tells you the frequency by a 
resonance
peak. They are a very common old school item for microwave frequency 
measurement in
a teaching setting. 

https://www.britannica.com/technology/wavemeter

Bob

> On Feb 12, 2017, at 12:16 PM, Robert Atkinson via time-nuts 
>  wrote:
> 
> In a word,Wavemeters. Classic US onwas the BC221 with built in 100kHz crystal 
> calibrator
> http://radionerds.com/index.php/BC-221
> British was the "Class D"http://www.royalsignals.org.uk/photos/classDno1.htm
> 
> For UHF and Microwave it was Lecher lines or cavity wavemeters.
> Robert G8RPI.
> 
> 
>  From: Scott Stobbe 
> To: Discussion of precise time and frequency measurement  
> Sent: Sunday, 12 February 2017, 6:08
> Subject: [time-nuts] Vintage Frequency Measurement
> 
> I was inspired recently coming across a Lampkin 105 frequency meter, as to
> how  frequency measurement was done before counters.
> 
> Certainly zero-beating a dial calibrated oscillator, would be one approach.
> 
> Is there a standout methodology or instrument predating counters?
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
> 
> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Vintage Frequency Measurement

[Bob Camp]

Hi

Counters go back at least into the early 1950’s. I started out with fully 
vacuum 
tube (except for diodes) counters obtained as surplus in the mid 1960’s. They
used some odd gas filled triodes. Everything in them could have been on the 
market
in 1947. They were not a common thing until the late 50’s. 

Prior to that (WWII era) the standard approach was to use a heterodyne frequency
meter. They could be quite complex. I once passed up a “deal” on one that 
spread 
out over several rack cabinets. The idea was that you produced a beat against 
this or that
and then beat it again against something else. Ultimately a meter or scope 
showed
you the phase offset. 

The heterodyne approach lived on in the era of the counter using a synthesizer 
as
the reference. The beat note went into an analog meter based audio frequency 
meter.
It allowed you do do cute things like servo to a target when grinding or 
plating something 
to frequency. 

One key thing to keep in mind: in the 1930’s it is rare to find a frequency 
spec that is 
not stated in percent (with some zeros involved). A  tight spec was in the 20  
ppm 
(or 0.002% ) range. The idea of a heated crystal as a reference was a “national 
standards” sort of thing in 1935. The crystal industry as we know it today 
really only dates
back to 1939. Before that the number of producers and the volume produced
was *very* small.

Bob


> On Feb 12, 2017, at 1:08 AM, Scott Stobbe  wrote:
> 
> I was inspired recently coming across a Lampkin 105 frequency meter, as to
> how  frequency measurement was done before counters.
> 
> Certainly zero-beating a dial calibrated oscillator, would be one approach.
> 
> Is there a standout methodology or instrument predating counters?
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] how many seconds out does GPS discipline being to improve Rubidium stability?

[Bob Camp]

Hi

Using ADEV as an example (the other stuff will have it’s own curves, but the 
result is the same):

A typical Rb should have a stability at short tau that goes as 1/ square 
root(Tau). If you are at 2x10^-11 at 1 second, you 
will be at 2x10^-12 at 100 seconds and 2x10^-13 at 1,000 seconds. Somewhere in 
the parts in 10^-13 that relation will
start to diverge from reality. 

A fairly normal low frequency OCXO has a stability that is fairly flat with tau 
in the 1 to 100 second range. If they have been
on power constantly that “flat zone" may extend to 1,000 seconds. Floors should 
be in the low parts in 10^-12 to mid parts
in 10^-13 range. 

A good OCXO *may* beat a normal Rb at 1,000 seconds. That may or may not be an 
issue in your case. It depends a lot 
on what you are trying to do.

Simple solutions: 

1) Run something better than an Rb. A hydrogen maser is one alternative (simple 
if you don’t have to pay for it).
2) Do all your measurements as three corner hats. You run two references and 
one DUT into gear that will do that sort of test.
3) Segment the measurements and use carefully selected references for those 
ranges. 

None of those are actually simple. Number 3 sounds cool until you realize that 
you are switching test setups around a lot and
the devices you are using still need a setup like 2 to figure out which ones to 
use. 

So do you need a GPS? What are the limits on your MTIE tests? (MTIE on an OCXO 
is highly dependent on several 
things so there is no simple number there). A very normal quartz based GPSDO 
might be a fine reference for your test. 

How much shorter are the other tests? Is ADEV at 1,000 seconds even of 
interest? If the answer is < 1,000 seconds a
Rb may not do you much good at all. 

Lots of twists and turns. 

Bob





> On Feb 11, 2017, at 5:52 PM, gkk gb <modjkl...@comcast.net> wrote:
> 
> Thanks Bob,
> 
> 
> 
> I should clarify the MTIE measurement extends 10 seconds (the others are 
> less time). Is it a reasonable question to ask if GPS is needed? Or are there 
> other variables that are involved?
> 
> 
> 
> Good point about the temperature stability, I hadn't considered that. Can I 
> place in a temperature chamber to provide a better thermal environment, or 
> does that cause other issues (vibration from blowers, EMI noise, etc.)? Other 
> ways to mitigate temperature changes?
> 
> 
> 
> It seems a Rubidium is good after a timescale of 100 s. What do people do 
> below 100 s to characterize quartz oscillators. Do they simply try to find 
> the most stable parts they can afford and break the x-axis (tau) into two 
> regions using difference references for each? If so, are there generally 
> accepted "gold" standards anyone can recommend for crystal products with the 
> best stability to use as a reference between 0.1 and 100 seconds, for 
> example? 
> 
> 
> 
> On February 11, 2017 at 6:29 AM Bob Camp <kb...@n1k.org> wrote:
> 
> Hi
> 
> Backing up a bit here.
> 
> On Feb 10, 2017, at 7:35 PM, gkk gb <modjkl...@comcast.net> wrote:
> 
> Hello experts, I need a Rubidium frequency reference for my company, and 
> wonder if I also need to GPS discipline it.
> 
> I characterize crystal-based OCXOs for ADEV, MTIE, and TDEV, and my longest 
> measurement time is 100,000 seconds (28 hours).
> 
> If your longest measurement is a 100,000 second ADEV, then your measurement 
> time will be out in the
> 1,000,000 to 10,000,000 second range. Is that really what you are doing?
> 
> If 100,000 seconds ADEV is your longest measurement, what is the shortest tau 
> you are interested in?
> A Rb is not going to be much use for testing a good OCXO at shorter tau. 
> Where the crossover happens
> depends a lot on the grade of OCXO you are working with. By the time you get 
> to 1 second
> most OCXO’s will be noticeably better than most Rb’s.
> 
> I'm looking at this graph from SRS for PRS10,
> 
> http://www.thinksrs.com/assets/instr/PRS10/PRS10diag2LG.gif
> 
> I would suggest that plot is probably not the best one to depend on for GPS 
> performance. In a GPSDO setting
> the cut over points are all over the place depending on which design you look 
> at.
> 
> and thinking that as long as I calibrate a Rubidium source annually, there's 
> no need for a GPS (since it only appears to degrade stability). Is this true 
> in general, or is the graph misleading me because it may be true here, but 
> not always.
> 
> The big issue is going to be temperature stability. If you have a Rb that is 
> (say) 5x10^-10 over 0 to 50C, that is likely 1x10^-11 / C (or maybe more). A 
> 2C delta in
> your lab as the HVAC cycles will give you a 2x10^-11 “hump” in your ADEV plot.
> 
> Also consider that if you want an “easy” measurement 

Re: [time-nuts] Neoprene rubber drops GPS multipath signals to zero

[Bob Camp]

Hi

For any microwave material, the good old “toss it in a microwave” test is a 
quick
and dirty one. If the material heats up, it’s lossy. Yes, there are other 
fairly exciting 
things that can happen other than it warming a bit …. 

Bob

> On Feb 11, 2017, at 5:51 PM, MLewis  wrote:
> 
> Interesting.
> My guess wasn't a material made for RF but a carbon added to give a decent 
> black colour.
> 
> "It is not inconceiveable that off-spec or scrap materials from the 
> production might end up as mousemats."  and "stealth material".
> Very interesting.
> At an airshow many years ago, these mouse pads were a promotional give-away 
> by the Department of National Defence in Canada...
> 
> I'm now seeing some multipath signals sneak through, usually in the single 
> digital strength but for brief moments as high as 15 dBs. Coming from 
> elevation 5 to 10 degrees, between azimuth 300 to 330 and also azimuth 30 and 
> 60. I'm suspecting the office tower at 135 that sticks up above the bank of 
> buildings. I'll have to add a 1" strip up to 3" high in LOS to that building 
> to see what that does.
> The other multipath signals remain at 0.0.
> 
> Michael
> 
> On 11/02/2017 1:22 PM, Poul-Henning Kamp wrote:
> > 
> >
> > I can guarantee you that it is not the neoprene itself which does it.
> >
> > It could be residual ZnO, used to catalyze polymerisation of the neoprene,
> > but more likely it is metal deliberately added to the neoprene to
> > change the RF impedance of the material.
> >
> > ...
> >
> > [1] If you arrange for the imperance to ramp from open to short you
> > have a "stealth material".
> >
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] The USFS Frequency Standard...

[Bob Camp]

Hi

One *could* make a WWVB “new modulation” receiver with some sort
of MCU demo board and a handful of parts. It would be fine for a basement
lab / learning sort of project. Given the way the semiconductor world works,
the longer you wait to start that project, the better a board you will have
as the base of the project. 

At the end of the project with everything working fine, you still have WWVB
as the “source”. Propagation issues still limit what you can achieve. 
MSF (as far as I know) is still on the air. That still is going to cause issues
if you are in the New England area. Miami is still a long way from Colorado.
If you happen to live in Denver, not much of a problem at all. 

How many people want to spend more than a year on that sort of thing when
a < $10 GPS USB dongle would do as good a job? It’s a back burner project
here. There isn’t a real big push to get it onto the front burner. Yes, 
following 
the masses like that is a bit sad. There are things that would be learned doing
this sort of thing. Some of them would be about WWVB. A few of the learnings
would be about GPS. As others have very correctly pointed out, diverse sources 
of time
are a good thing. We are headed towards a GPS monoculture. 

Bob


> On Feb 10, 2017, at 8:02 PM, paul swed  wrote:
> 
> Burt you missed nothing. It would appear that all good intentions did not
> lead to new business. So there you go the old receivers useless and no new
> ones made.
> Certainly all of the old ones can be made to work using the cheatn dpskr
> shared with time nuts. But boy compared to the gpsdo's this lazy time nut
> likes the simplicity and economics. Sure I can't say I am the first kid on
> the block with a USFS but that hasn't been much of a topic lately.
> 
> I do fire up the old wwvb receivers just to make sure the cheatn dpskr
> works and that they still do. But 99.9% of the time its the gpsdo these
> days. Its there until it isn't.
> Regards
> Paul
> WB8TSL
> 
> On Fri, Feb 10, 2017 at 3:47 PM, Burt I. Weiner  wrote:
> 
>> Technically speaking, the United State Frequency Standard (USFS) is still
>> considered to be transmitted via WWVB on 60 kHz, essentially making WWVB
>> the USFS.  But is WWVB still a usable frequency standard reference since
>> they've gone to phase shifting their signal for time keeping purposes?
>> Will GPS become the "official" USFS reference signal?
>> 
>> Is there a 60 kHz WWVB receiver out there that can still be used as
>> reference?  Is there a commercially made receiver out there that now uses
>> the phase shifting technique of WWVB for accurate time keeping?
>> 
>> Have I missed something?
>> 
>> Burt, K6OQK
>> 
>> Burt I. Weiner Associates
>> Broadcast Technical Services
>> Glendale, California U.S.A.
>> b...@att.net
>> K6OQK
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/m
>> ailman/listinfo/time-nuts
>> and follow the instructions there.
>> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] how many seconds out does GPS discipline being to improve Rubidium stability?

[Bob Camp]

Hi

Backing up a bit here.


> On Feb 10, 2017, at 7:35 PM, gkk gb  wrote:
> 
> Hello experts, I need a Rubidium frequency reference for my company, and 
> wonder if I also need to GPS discipline it.
> 
> 
> I characterize crystal-based OCXOs for ADEV, MTIE, and TDEV, and my longest 
> measurement time is 100,000 seconds (28 hours). 

If your longest measurement is a 100,000 second ADEV, then your measurement 
time will be out in the 
1,000,000 to 10,000,000 second range. Is that really what you are doing? 

If 100,000 seconds ADEV is your longest measurement, what is the shortest tau 
you are interested in?
A Rb is not going to be much use for testing a good OCXO at shorter tau. Where 
the crossover happens
depends a lot on the grade of OCXO you are working with. By the time you get to 
1 second 
most OCXO’s will be noticeably better than most Rb’s.

> 
> 
> I'm looking at this graph from SRS for PRS10,
> 
> 
> http://www.thinksrs.com/assets/instr/PRS10/PRS10diag2LG.gif

I would suggest that plot is probably not the best one to depend on for GPS 
performance.  In a GPSDO setting 
the cut over points are all over the place depending on which design you look 
at. 

> 
> 
> and thinking that as long as I calibrate a Rubidium source annually, there's 
> no need for a GPS (since it only appears to degrade stability). Is this true 
> in general, or is the graph misleading me because it may be true here, but 
> not always.

The big issue is going to be temperature stability. If you have a Rb that is 
(say) 5x10^-10 over 0 to 50C, that is likely 1x10^-11 / C (or maybe more). A 2C 
delta in 
your lab as the HVAC cycles will give you a 2x10^-11 “hump” in your ADEV plot. 

Also consider that if you want an “easy” measurement of the devices you are 
testing, the reference source probably should be 
5X better than what you expect out of the DUT. You probably will not have that 
luxury in this case. That gets you into multiple
references and things like three corner hat testing. 

> 
> 
> So my question, is a GPS necessary to discipline a Rubidium standard to 
> characterize the best crystal oscillators for stability, or can I do without 
> it (and just calibrate the Rubidium annually to maintain accuracy) and 
> actually get better stability?
> 
> 
> How many seconds out is a GPS generally needed to improve accuracy from a 
> Rubidium standard?

If you really are running 1,000,000 to 10,000,000 second long tests, you need 
the GPS.

Lots of variables 

Bob


> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

To be fair to these guys, they have a number of challenges that have nothing to
do with technology. They cross link to other companies and have little control 
over how each one operates. Here in the US, we have multiple regulatory 
agencies (it happens at the state, federal, and international level).  they all 
are involved 
in any change. That makes for a very long and drawn out dance when you fiddle
with this or that. Also, in many cases are the shareholders in the company 
who seem to have goals as well ….

Not an easy thing.

Bob 

> On Feb 11, 2017, at 5:22 AM, Magnus Danielson  
> wrote:
> 
> Work is already underway to improve the relicense of power grid operations. 
> They is smarting up quickly. The PMU/synchrophasor measurements depend on UTC 
> and before it can be used full-blown for operation the single point of 
> failure needs to be handled.
> 
> Cheers,
> Magnus
> 
> On 02/09/2017 11:19 PM, Peter Reilley wrote:
>> Isn't this "hard" lock to UTC creating a single point of failure? A
>> solar burst, an EMP, or
>> a software error could leave us all in the dark.   After all, smart
>> inverters could be
>> programmed to act like big lumps of rotating iron and be compatible with
>> the current
>> system.
>> 
>> Pete.
>> 
>> On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:
>>> 
>>> In message
>>> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
>>> verpod.net>, "Thomas D. Erb" writes:
>>> 
 I was wondering if anyone was familiar with this proposal, is this
 a uncoupling of line frequency from a time standard ?
>>> The interesting thing about this is that all research and experiments
>>> (for instance on the danish island Bornholm) indicates that the only
>>> way we stand any chance of keeping future AC grids under control in the
>>> medium term is to lock the frequency *hard* to UTC.
>>> 
>>> Its a very interesting topic.
>>> 
>>> In the traditional AC grid power is produced by big heavy lumps of
>>> rotating iron.  This couples the grid frequency tightly to the
>>> power-balance of the grid:  If the load increases, the generators
>>> magnetic field drags harder slowing the rotor, lowering the frequency
>>> and vice versa.
>>> 
>>> This makes the grid frequency a "proxy signal" for the power balance,
>>> and very usefully so, because it travels well and noiselessly through
>>> the entire AC grid.
>>> 
>>> The only other possible "balance signal" is the voltage, and it
>>> suffers from a host of noise mechanisms, from bad contacts and
>>> lightning strikes to temperature, but worst of all, it takes double
>>> hit when you start big induction motors, thus oversignalling the
>>> power deficit.
>>> 
>>> Where the frequency as "proxy" for grid balance reacts and can
>>> be used to steering on a 100msec timescale, you need to average
>>> a voltage "proxy" signal for upwards of 20 seconds to get the
>>> noise down to level where you don't introduce instability.
>>> 
>>> The big picture problem is that we are rapidly retiring the rotating
>>> iron, replacing it with switch-mode converters which do not "couple"
>>> the frequency to power balance.
>>> 
>>> For instance HVDC/AC converters, solar panel farms, and increasingly
>>> wind generators, do not try to drag down the frequency when they
>>> cannot produce more or drag the frequency up when they can produce
>>> more power, they just faithfully track whatever frequency all the
>>> rotating lumps of iron have agreed on.
>>> 
>>> As more and more rotating iron gets retired, the grid frequency
>>> eventually becomes useless as a "proxy-signal" for grid balance.
>>> 
>>> Informal and usually undocumented experiments have already shown
>>> that areas of grids which previously were able to run in "island"
>>> mode, are no longer able to do so, due to shortage of rotating iron.
>>> 
>>> One way we have found to make the voltage a usable fast-reacting
>>> proxy for grid power-balance, is to lock the frequency to GNSS at
>>> 1e-5 s level at all major producers, which is trivial for all the
>>> switch-mode kit, and incredibly hard and energy-inefficient for the
>>> rotating iron producers.
>>> 
>>> The other way is to cut the big grids into smaller grids with HVDC
>>> connections to decouple the frequencies, which allows us to relax
>>> the frequency tolerance for each of these subgrids substantially.
>>> 
>>> This solution gets even better if you load the HVDC up with capacitance
>>> to act as a short time buffers, but the consequences in terms of
>>> short circuit energy are ... spectacular?
>>> 
>>> (It is already bad enough with cable capacitance in long HVDC
>>> connections, do the math on 15nF/Km and 100.000 kV yourself.)
>>> 
>>> All these issues are compounded by the fact that the "50/60Hz or
>>> bust" mentality has been tatooed on the nose of five generations
>>> of HV engineers, to such an extent that many of them are totally
>>> incapable of even imagining anything else, and they all 

Re: [time-nuts] The USFS Frequency Standard...

[Bob Camp]

Hi

The simple answer is that WWVB still has the good old AM modulation on it. 
Any of the old *time* receivers will work just fine with the current broadcast
format. There are a number of them that show up on the surplus market. The
gotcha is those receivers that wanted to get both frequency and time. Those 
are toast without some heroic modification efforts. 

The world is still waiting for the magic chips that will decode the new format
to show up on the market. The issue is that you *could* do a design that uses 
a  hundred dollars of parts. Poof! you have a commercial device to sell.
Next day out come the magic chips for < $1 and 80% of your BOM is replaced.
Your competitor now has a unit on the market for 1/5 your price. You better 
*hope*
you recovered all of your up front costs before that happens. You also now have
a group of customers that expect at least 20 years of free updates and free  
support 
on your gizmo ….and it’s a dead end for you. Zero dollars in on that design and 
many
many dollars out every year. Simple answer is not to go down that road. Wait for
the magic chips to show up. That’s the way it’s worked for at least 40 years. 

Basement lab wise, sure you can come up with this or that to demodulate the 
signal.
That’s been done and is being done. That’s a long ways from a commercial rack 
mount
gizmo that “just works”. 

On a more practical basis, GPS is traceable to UTC and to USNO. By law USNO is 
the 
authority on time in the US. NIST is the authority on frequency. That 
distinction goes back
to a long gone era when time was a “navigation” thing and frequency was a 
“commerce” 
function.  In either case, you need to be able (legally) to trace via a valid 
path to whatever
each of them say is correct. These days there are *lots* of paths. They all 
work and all
have tolerance estimates on them. On a global basis you need to trace back to 
UTC and 
BIH. It’s the same idea only one level higher. 

Bob

> On Feb 10, 2017, at 3:47 PM, Burt I. Weiner  wrote:
> 
> Technically speaking, the United State Frequency Standard (USFS) is still 
> considered to be transmitted via WWVB on 60 kHz, essentially making WWVB the 
> USFS.  But is WWVB still a usable frequency standard reference since they've 
> gone to phase shifting their signal for time keeping purposes?  Will GPS 
> become the "official" USFS reference signal?
> 
> Is there a 60 kHz WWVB receiver out there that can still be used as 
> reference?  Is there a commercially made receiver out there that now uses the 
> phase shifting technique of WWVB for accurate time keeping?
> 
> Have I missed something?
> 
> Burt, K6OQK
> 
> Burt I. Weiner Associates
> Broadcast Technical Services
> Glendale, California U.S.A.
> b...@att.net
> K6OQK 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

> On Feb 9, 2017, at 6:55 PM, Poul-Henning Kamp  wrote:
> 
> 
> In message 
> 

Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

Hi

If you are talking about big power gizmos, putting a GPSDO on them is pretty 
simple 
cost and system wise. Given the fact that 10 ns sync is not required, the 
actual implementation 
might be pretty cheap.

Bob


> On Feb 9, 2017, at 5:19 PM, Peter Reilley  wrote:
> 
> Isn't this "hard" lock to UTC creating a single point of failure? A solar 
> burst, an EMP, or
> a software error could leave us all in the dark.   After all, smart inverters 
> could be
> programmed to act like big lumps of rotating iron and be compatible with the 
> current
> system.
> 
> Pete.
> 
> On 2/9/2017 4:31 PM, Poul-Henning Kamp wrote:
>> 
>> In message 
>> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
>> verpod.net>, "Thomas D. Erb" writes:
>> 
>>> I was wondering if anyone was familiar with this proposal, is this
>>> a uncoupling of line frequency from a time standard ?
>> The interesting thing about this is that all research and experiments
>> (for instance on the danish island Bornholm) indicates that the only
>> way we stand any chance of keeping future AC grids under control in the
>> medium term is to lock the frequency *hard* to UTC.
>> 
>> Its a very interesting topic.
>> 
>> In the traditional AC grid power is produced by big heavy lumps of
>> rotating iron.  This couples the grid frequency tightly to the
>> power-balance of the grid:  If the load increases, the generators
>> magnetic field drags harder slowing the rotor, lowering the frequency
>> and vice versa.
>> 
>> This makes the grid frequency a "proxy signal" for the power balance,
>> and very usefully so, because it travels well and noiselessly through
>> the entire AC grid.
>> 
>> The only other possible "balance signal" is the voltage, and it
>> suffers from a host of noise mechanisms, from bad contacts and
>> lightning strikes to temperature, but worst of all, it takes double
>> hit when you start big induction motors, thus oversignalling the
>> power deficit.
>> 
>> Where the frequency as "proxy" for grid balance reacts and can
>> be used to steering on a 100msec timescale, you need to average
>> a voltage "proxy" signal for upwards of 20 seconds to get the
>> noise down to level where you don't introduce instability.
>> 
>> The big picture problem is that we are rapidly retiring the rotating
>> iron, replacing it with switch-mode converters which do not "couple"
>> the frequency to power balance.
>> 
>> For instance HVDC/AC converters, solar panel farms, and increasingly
>> wind generators, do not try to drag down the frequency when they
>> cannot produce more or drag the frequency up when they can produce
>> more power, they just faithfully track whatever frequency all the
>> rotating lumps of iron have agreed on.
>> 
>> As more and more rotating iron gets retired, the grid frequency
>> eventually becomes useless as a "proxy-signal" for grid balance.
>> 
>> Informal and usually undocumented experiments have already shown
>> that areas of grids which previously were able to run in "island"
>> mode, are no longer able to do so, due to shortage of rotating iron.
>> 
>> One way we have found to make the voltage a usable fast-reacting
>> proxy for grid power-balance, is to lock the frequency to GNSS at
>> 1e-5 s level at all major producers, which is trivial for all the
>> switch-mode kit, and incredibly hard and energy-inefficient for the
>> rotating iron producers.
>> 
>> The other way is to cut the big grids into smaller grids with HVDC
>> connections to decouple the frequencies, which allows us to relax
>> the frequency tolerance for each of these subgrids substantially.
>> 
>> This solution gets even better if you load the HVDC up with capacitance
>> to act as a short time buffers, but the consequences in terms of
>> short circuit energy are ... spectacular?
>> 
>> (It is already bad enough with cable capacitance in long HVDC
>> connections, do the math on 15nF/Km and 100.000 kV yourself.)
>> 
>> All these issues are compounded by the fact that the "50/60Hz or
>> bust" mentality has been tatooed on the nose of five generations
>> of HV engineers, to such an extent that many of them are totally
>> incapable of even imagining anything else, and they all just "know"
>> that DC is "impossible".
>> 
>> In the long term, HVDC is going to take over, because it beats HVAC
>> big time on long connections, and it is only a matter of getting
>> semiconductors into shape before that happens.  That however,
>> is by no means a trivial task:  It's all about silicon purity.
>> 
>> 
> 
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.

Re: [time-nuts] Line Frequency standard change - Possible ?

[Bob Camp]

> On Feb 9, 2017, at 4:31 PM, Poul-Henning Kamp  wrote:
> 
> 
> In message 
> <4fbdd81ddf04fc46870db1b9a747269202916...@mbx032-e1-va-8.exch032.ser
> verpod.net>, "Thomas D. Erb" writes:
> 
>> I was wondering if anyone was familiar with this proposal, is this
>> a uncoupling of line frequency from a time standard ?
> 
> The interesting thing about this is that all research and experiments
> (for instance on the danish island Bornholm) indicates that the only
> way we stand any chance of keeping future AC grids under control in the
> medium term is to lock the frequency *hard* to UTC.
> 
> Its a very interesting topic.
> 
> In the traditional AC grid power is produced by big heavy lumps of
> rotating iron.  This couples the grid frequency tightly to the
> power-balance of the grid:  If the load increases, the generators
> magnetic field drags harder slowing the rotor, lowering the frequency
> and vice versa.
> 
> This makes the grid frequency a "proxy signal" for the power balance,
> and very usefully so, because it travels well and noiselessly through
> the entire AC grid.
> 
> The only other possible "balance signal" is the voltage, and it
> suffers from a host of noise mechanisms, from bad contacts and
> lightning strikes to temperature, but worst of all, it takes double
> hit when you start big induction motors, thus oversignalling the
> power deficit.
> 
> Where the frequency as "proxy" for grid balance reacts and can
> be used to steering on a 100msec timescale, you need to average
> a voltage "proxy" signal for upwards of 20 seconds to get the
> noise down to level where you don't introduce instability.
> 
> The big picture problem is that we are rapidly retiring the rotating
> iron, replacing it with switch-mode converters which do not "couple"
> the frequency to power balance.
> 
> For instance HVDC/AC converters, solar panel farms, and increasingly
> wind generators, do not try to drag down the frequency when they
> cannot produce more or drag the frequency up when they can produce
> more power, they just faithfully track whatever frequency all the
> rotating lumps of iron have agreed on.
> 
> As more and more rotating iron gets retired, the grid frequency
> eventually becomes useless as a "proxy-signal" for grid balance.
> 
> Informal and usually undocumented experiments have already shown
> that areas of grids which previously were able to run in "island"
> mode, are no longer able to do so, due to shortage of rotating iron.
> 
> One way we have found to make the voltage a usable fast-reacting
> proxy for grid power-balance, is to lock the frequency to GNSS at
> 1e-5 s level at all major producers, which is trivial for all the
> switch-mode kit, and incredibly hard and energy-inefficient for the
> rotating iron producers.
> 
> The other way is to cut the big grids into smaller grids with HVDC
> connections to decouple the frequencies, which allows us to relax
> the frequency tolerance for each of these subgrids substantially.
> 
> This solution gets even better if you load the HVDC up with capacitance
> to act as a short time buffers, but the consequences in terms of
> short circuit energy are ... spectacular?
> 
> (It is already bad enough with cable capacitance in long HVDC
> connections, do the math on 15nF/Km and 100.000 kV yourself.)
> 
> All these issues are compounded by the fact that the "50/60Hz or
> bust" mentality has been tatooed on the nose of five generations
> of HV engineers,

Umm… you left out the 25Hz power system that runs across the 
road just a few miles from here :) Some of these ideas take a *long* time
to die. It’s been happily doing it’s thing for over a century. 

> to such an extent that many of them are totally
> incapable of even imagining anything else, and they all just "know"
> that DC is "impossible”.

Except we’ve had HVDC distribution running around for many decades
and it seems to work quite well. Indeed that’s your point here. 

> 
> In the long term, HVDC is going to take over, because it beats HVAC
> big time on long connections, and it is only a matter of getting
> semiconductors into shape before that happens.  That however,
> is by no means a trivial task:  It's all about silicon purity.

… or silicon carbide purity or something even more weird and (so far)
poorly understood.

Bob

> 
> 
> -- 
> Poul-Henning Kamp   | UNIX since Zilog Zeus 3.20
> p...@freebsd.org | TCP/IP since RFC 956
> FreeBSD committer   | BSD since 4.3-tahoe
> Never attribute to malice what can adequately be explained by incompetence.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the 

Re: [time-nuts] eLoran is up and operating. Looking good

[Bob Camp]

Hi

P
> On Feb 7, 2017, at 11:17 PM, Gary E. Miller <g...@rellim.com> wrote:
> 
> Yo Bob!
> 
> On Tue, 7 Feb 2017 21:38:52 -0500
> Bob Camp <kb...@n1k.org> wrote:
> 
>> Teaching
>> the NTP drivers when not to use the data and how to compare data is a
>> do-able thing.  It’s just that nobody has ever bothered to do it.
> 
> The NTPsec team would love to work with anyone that has a device
> that could use an improved NTP driver.

I have absolutely no doubt of that.The issue is not being *able* to do 
the driver and get it accepted. The issue is that there is …errr … 
work involved. :)

Bob

> 
>> Coming up with some simple to use tools to estimate the errors and
>> config them in is likely the only practical way to do it.
> 
> NTPsec has done a lot of recent work on tools.  We are open to any
> suggestions or requests that people may make.
> 
> RGDS
> GARY
> ---
> Gary E. Miller Rellim 109 NW Wilmington Ave., Suite E, Bend, OR 97703
>   g...@rellim.com  Tel:+1 541 382 8588
> 
>   Veritas liberabit vos. -- Quid est veritas?
>"If you can’t measure it, you can’t improve it." - Lord Kelvin
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.