date:20141214


Hi,

Agree. It's not ideal. In it's simplicity it achieves first degree delay 
compensation, but it is not the best of signals you get.


You need to treat the signal as being essentially a sine, and overcome 
the slew-rate.


It may be a useful technique besides it's limits.

Cheers,
Magnus

On 12/15/2014 03:45 AM, Bob Camp wrote:

Hi


…. but …


Low edge speeds => poor signal to noise => high jitter.

The result is a clock that aligns, but has high(er) jitter compared to a 
conventional square wave clock. Most of the “lower phase noise / lower jitter” 
progress in CMOS logic has gone hand in hand with faster edge rates.

Bob



On Dec 14, 2014, at 8:27 PM, Magnus Danielson  
wrote:

Bob,

On 12/14/2014 02:10 AM, Robert Darby wrote:

This is an paper that may be of some interest to those interested in
clock distribution.  The author, Jinyuan Wu has done considerable work
on FPGA TIC's with Fermi Lab.

http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf


How incredibly cunning!

Cheers,
Magnus
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Re: [time-nuts] Fwd: Homebrew frequency counter, need help


Hi Bob,

On 12/15/2014 02:22 AM, Bob Camp wrote:

Hi

(yes, this is a bit confusing … it’s my replies to a forward from Magnus who 
got a bounce on submittal)


Whe're confusing Bob, I think they got that part now.


Begin forwarded message:

Date: December 14, 2014 at 7:57:39 PM EST
From: Magnus Danielson 
To: Bob Camp 
Cc: mag...@rubidium.se
Subject: Re: [time-nuts] Homebrew frequency counter, need help

Hi Bob,

Repost my email as I accidentally posted it with wrong from address.

On 12/14/2014 08:26 PM, Bob Camp wrote:

… and this is where it gets complicated. I would toss in the Hadamard deviation 
into that mix as well.


The Hadamard deviation is a great tool as it is not sensitive to linear 
frequency drift as Allan deviation is. This would help to remove the systematic 
effect, just as a quadratic curve-fitting of the raw-data and ADEV of the 
residual.


I like the Hadamard because it’s a bit better for mapping to the frequency 
domain. It’s what HP used to get phase noise from phase error data. I find that 
it gives a bit better detail on some types of problems.


I use if regularly, but TimeLab unfortunatly does not have the MHDEV.


The whole process of getting *correct* versions of things into a program is 
(unfortunately) much harder than simply tossing it in there. I’m glad that the 
stuff in TimeLab works correctly.


I do know that, and it's not the only culprit, John naturally wants one 
that works correctly in update form, and not batch form. He also does 
not want too many of these running in parallel.






Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with the 
same properties for drift. Similarly will Time Hadarmard Deviation (THDEV) 
replace TDEV. However, for longer taus you want better processing, so therefore 
you want to consider the TOTAL set of deviations, such that confidence 
intervals is better.


If I had to only use three, I would include it with modified ADEV (MDEV) and 
TDEV. All three are available in TimeLab with the click of a button. If you 
start getting lots of data (9,000 points per second) I would toss in a 
frequency domain (FFT) analysis as well. FFT on phase data is not (as far as I 
know) a feature of TimeLab.


FFT on phase-data is only available in TimeLab when doing phase-noise 
measurements. FFT is the way to analyse systematic noise rather than random 
noise where ADEV and friends is being used. You need to separate them, and the 
ADEV plot is not good for both.

There is a set of FFT based ADEV-style measures, which uses FFT, filtering of 
the various ADEV styles. There is a nice set of articles covering that 
approach, and actually the only style of ADEV processing that I haven't yet 
implemented, even if I have done most others.


Stable-32 will take phase data and convert it to the frequency domain.


Depending on what processing you are going to do, phase or frequency may be 
optimum.
Phase is better for normal deviations.
Frequency is better for modified deviations.


Stable 32 is nice in that it will convert one to the other with the click of a 
button.


I'm sure it is fine, but it does not fit my needs in one way, it doesn't 
run on Linux. My milage with Wine on different applications vary. 
TimeLab works, but is free. For an application I pay for and not knowing 
it works would be strange. Besides, I try to minimize my dependence on 
Windows apps, as they tend to bite me. Stable 32 thus does not fit my 
needs very well, even if I'm sure it is a fine application.







To start with, on all of these measures, you are looking for bumps and spikes. 
They are telling you that something is wrong. If you flip over to the phase 
plot in TimeLab, spikes and abrupt steps in it also are telling you the same 
sort of thing. Exactly what this or that bump is telling you may not be obvious 
at first. Posting plots to the list is a great way to get things sorted out.


Bumps, spikes and slopes... ADEV isn't the only tool one should be using, FFT 
might be much better for systematic noises.


Right, so when you see them, alarm bells should go off. Something is indeed 
wrong and further investigation is required.


Maybe, ADEV is good at smoothing out things, so spikes in spectrum-analysis 
might not be as easy to spot in the ADEV form.


A good reason to look at multiple data sets and analysis approaches


Which is what I am say, do not rely on ADEV alone, and move your 
analysis of systematics out of the ADEV plot and remove those effects 
fro the ADEV plot so it becomes better at modeling the random noises.





In the end of the day, there is an overbeleife in ADEV both as a scale as well 
as a processing tool, to analyze deviations, without considering the separation 
of various systmeatic effect and systematic noises, while ADEV and friends is 
there to analyze random noise types, it does not handle systematics good. Seems 
like we have to kill ADEV as the universal measure. Ah well.


It’s been around much longer than some of t

Re: [time-nuts] Homebrew frequency counter, need help

2014-12-14 Thread Li Ang


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Re: [time-nuts] The Trapezoidal Clocking

Hi

…. but …

Low edge speeds => poor signal to noise => high jitter.

The result is a clock that aligns, but has high(er) jitter compared to a 
conventional square wave clock. Most of the “lower phase noise / lower jitter” 
progress in CMOS logic has gone hand in hand with faster edge rates. 

Bob

> On Dec 14, 2014, at 8:27 PM, Magnus Danielson  
> wrote:
> 
> Bob,
> 
> On 12/14/2014 02:10 AM, Robert Darby wrote:
>> This is an paper that may be of some interest to those interested in
>> clock distribution.  The author, Jinyuan Wu has done considerable work
>> on FPGA TIC's with Fermi Lab.
>> 
>> http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf
> 
> How incredibly cunning!
> 
> Cheers,
> Magnus
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Re: [time-nuts] The Trapezoidal Clocking


Bob,

On 12/14/2014 02:10 AM, Robert Darby wrote:

This is an paper that may be of some interest to those interested in
clock distribution.  The author, Jinyuan Wu has done considerable work
on FPGA TIC's with Fermi Lab.

http://www-ppd.fnal.gov/EEDOffice-w/Projects/ckm/comadc/TrapezCLK1b.pdf


How incredibly cunning!

Cheers,
Magnus
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Hi

> On Dec 14, 2014, at 8:05 PM, Pete Lancashire  wrote:
> 
> And 'scope probes :-)

Ok, that’s just plain not fair. I could accept the motherland of bumpers and 
handles. Tossing in scope probes … you are not to expect the usual fruit basket 
from me at Christmas :)

Bob

> On Dec 14, 2014 12:59 PM, "Bob Camp"  wrote:
> 
>> Hi
>> 
>> 
>>> On Dec 14, 2014, at 3:50 PM, Scott McGrath  wrote:
>>> 
>>> Much of the Malaysian Agilent gear uses this style of case with a
>> wraparound bumper in place of the system II feet and feet are removed when
>> gear is rack mounted.
>>> 
>>> One of my best surplus buys ever was a huge crate of mixed mounting
>> hardware feet / rack flanges etc I've been using that box o stuff for 10
>> years
>> 
>> Somewhere there’s a building full of gear all of which is missing it’s
>> feet and bumpers …
>> 
>> You are lucky to have found that box. In most cases they get tossed out
>> with the trash. The same is true of many of the fancy i/o cables, they get
>> put into the copper recycle pile and are gone…
>> 
>> Bob
>> 
>>> 
>>> Content by Scott
>>> Typos by Siri
>>> 
 On Dec 14, 2014, at 3:09 PM, Bob Camp  wrote:
 
 Hi
 
 The desktop version (with handle) used the rubber “bumper” wrap around
>> for feet. The bumpers got pulled when they were rack mounted. The ones that
>> got put back on may or may not be identical to the originals. That’s a very
>> normal part of the surplus process. The 100% correct HP original case on
>> the box as HP built it did not use the clip on feet.
 
 The reason for this is pretty simple. The Z3801 / Z3805 came before the
>> “instrument” versions of the same products. The internal case structure is
>> same/ same. The instrument simply gets a gray sheet metal jacket that fits
>> around the Z38xx box. That’s the way HP designed it. Since its just a
>> jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got
>> rack mounted and the feet / bumpers were tossed. I have a *lot* of very
>> legit surplus HP gear that did not come with feet or bumpers.
 
 Bob
 
> On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> drkir...@kirkbymicrowave.co.uk> wrote:
> 
> On 14 December 2014 at 19:32, Bob Camp  wrote:
> 
>>> There are not the usual 3 holes underneath where feet go.
>> 
>> I understand that they are different. The problem is the same though.
>> Pulling a box in and out of a rack with feet or bumpers on it is a pain.
>> They often get “lost” early in the instrument’s life. Often it’s a standard
>> process on all gear as it comes into the facility.  All of the un-needed
>> bits and pieces go into a big pile. When the feet (or whatever) are found
>> later in life they may or may not be re-installed correctly. They might not
>> even be the ones that came with the instrument.
>> 
>> Bob
> 
> I am not sure if you are following me. On most (all??) HP kit I have
> seen, there are 3 holes at each corner of the bottom, where is
> possible to fit feet if one is going to use it on a desktop, rather
> than a rack. This unit does not have those holes, so it would be
> impossible to fit the usual HP feet on it.
> 
> Looking around, I have 15 bits of HP kit,  all of which have holes in
> the corner for feet. But this 58503A, with the Chinese box, does not
> have the holes. I don't know whether the 85053A is supposed to have
> them, or whether this is just a flaw in the design of the counterfeit.
> 
> Dave
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 ___
 time-nuts mailing list -- time-nuts@febo.com
 To unsubscribe, go to
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[time-nuts] Fwd: Homebrew frequency counter, need help

Hi

(yes, this is a bit confusing … it’s my replies to a forward from Magnus who 
got a bounce on submittal)

> Begin forwarded message:
> 
> Date: December 14, 2014 at 7:57:39 PM EST
> From: Magnus Danielson 
> To: Bob Camp 
> Cc: mag...@rubidium.se
> Subject: Re: [time-nuts] Homebrew frequency counter, need help
> 
> Hi Bob,
> 
> Repost my email as I accidentally posted it with wrong from address.
> 
> On 12/14/2014 08:26 PM, Bob Camp wrote:
>>> Since I really want to reduce the noise, what is the best test set you
>>> suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2
>>> OCXO,
>> 
>> If the MV89’s are in good working condition, they are the best thing to 
>> compare.The have the best ADEV of the group you have available I would 
>> check them for output level and stability before I trusted them. There 
>> are a lot of defective parts on the market. People get some, sort them 
>> and sell the bad ones. The bad ones just keep getting re-sold again and 
>> again … My guess is that they were good parts at one time and they got 
>> damaged when pulled off boards. If you use them, keep them on power at 
>> all times. Any OCXO will do better if you run it that way.
> 
> In order to test if systematics is messing badly with you, measure the 
> ADEV of the oscillator as it is steered (and stabilized) to a number of 
> different frequencies. For larger offsets to the counter reference, 
> multiple beatings occurs within the regression interval. You want that 
> number to be an even number of beats, or the beat count to be so large 
> that the phase of the last beat does not care. Linear regression helps 
> out, as it weighs out the outermost measures compared to the central one, 
> making the beating at the beginning and end not care as much.
> 
> These are *systematic* noise effects, and as you play around with 
> systematics and processing, you might have the systematics works for or 
> against you, but at the same time, the random noise you try to measure 
> will suffer the processing filtering, and you need to recall that. If you 
> balance these properly, you can make good and correct measurements, it's 
> just that few do.
> 
> Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system 
> noises as they show up there should be estimated separately and removed 
> from the random noise estimates. They have *way* different behaviors.
 
 … and this is where it gets complicated. I would toss in the Hadamard 
 deviation into that mix as well.
>>> 
>>> The Hadamard deviation is a great tool as it is not sensitive to linear 
>>> frequency drift as Allan deviation is. This would help to remove the 
>>> systematic effect, just as a quadratic curve-fitting of the raw-data and 
>>> ADEV of the residual.
>> 
>> I like the Hadamard because it’s a bit better for mapping to the frequency 
>> domain. It’s what HP used to get phase noise from phase error data. I find 
>> that it gives a bit better detail on some types of problems.
> 
> I use if regularly, but TimeLab unfortunatly does not have the MHDEV.

The whole process of getting *correct* versions of things into a program is 
(unfortunately) much harder than simply tossing it in there. I’m glad that the 
stuff in TimeLab works correctly. 

> 
>>> 
>>> Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with 
>>> the same properties for drift. Similarly will Time Hadarmard Deviation 
>>> (THDEV) replace TDEV. However, for longer taus you want better processing, 
>>> so therefore you want to consider the TOTAL set of deviations, such that 
>>> confidence intervals is better.
>>> 
 If I had to only use three, I would include it with modified ADEV (MDEV) 
 and TDEV. All three are available in TimeLab with the click of a button. 
 If you start getting lots of data (9,000 points per second) I would toss 
 in a frequency domain (FFT) analysis as well. FFT on phase data is not (as 
 far as I know) a feature of TimeLab.
>>> 
>>> FFT on phase-data is only available in TimeLab when doing phase-noise 
>>> measurements. FFT is the way to analyse systematic noise rather than random 
>>> noise where ADEV and friends is being used. You need to separate them, and 
>>> the ADEV plot is not good for both.
>>> 
>>> There is a set of FFT based ADEV-style measures, which uses FFT, filtering 
>>> of the various ADEV styles. There is a nice set of articles covering that 
>>> approach, and actually the only style of ADEV processing that I haven't yet 
>>> implemented, even if I have done most others.
>> 
>> Stable-32 will take phase data and convert it to the frequency domain.
> 
> Depending on what processing you are going to do, phase or frequency may be 
> optimum.
> Phase is better for normal deviations.
> Frequency is better for modified deviations.

Stable 32 is nice in that it wil

Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Pete Lancashire

And 'scope probes :-)
On Dec 14, 2014 12:59 PM, "Bob Camp"  wrote:

> Hi
>
>
> > On Dec 14, 2014, at 3:50 PM, Scott McGrath  wrote:
> >
> > Much of the Malaysian Agilent gear uses this style of case with a
> wraparound bumper in place of the system II feet and feet are removed when
> gear is rack mounted.
> >
> > One of my best surplus buys ever was a huge crate of mixed mounting
> hardware feet / rack flanges etc I've been using that box o stuff for 10
> years
>
> Somewhere there’s a building full of gear all of which is missing it’s
> feet and bumpers …
>
> You are lucky to have found that box. In most cases they get tossed out
> with the trash. The same is true of many of the fancy i/o cables, they get
> put into the copper recycle pile and are gone…
>
> Bob
>
> >
> > Content by Scott
> > Typos by Siri
> >
> >> On Dec 14, 2014, at 3:09 PM, Bob Camp  wrote:
> >>
> >> Hi
> >>
> >> The desktop version (with handle) used the rubber “bumper” wrap around
> for feet. The bumpers got pulled when they were rack mounted. The ones that
> got put back on may or may not be identical to the originals. That’s a very
> normal part of the surplus process. The 100% correct HP original case on
> the box as HP built it did not use the clip on feet.
> >>
> >> The reason for this is pretty simple. The Z3801 / Z3805 came before the
> “instrument” versions of the same products. The internal case structure is
> same/ same. The instrument simply gets a gray sheet metal jacket that fits
> around the Z38xx box. That’s the way HP designed it. Since its just a
> jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got
> rack mounted and the feet / bumpers were tossed. I have a *lot* of very
> legit surplus HP gear that did not come with feet or bumpers.
> >>
> >> Bob
> >>
> >>> On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> >>>
> >>> On 14 December 2014 at 19:32, Bob Camp  wrote:
> >>>
> > There are not the usual 3 holes underneath where feet go.
> 
>  I understand that they are different. The problem is the same though.
> Pulling a box in and out of a rack with feet or bumpers on it is a pain.
> They often get “lost” early in the instrument’s life. Often it’s a standard
> process on all gear as it comes into the facility.  All of the un-needed
> bits and pieces go into a big pile. When the feet (or whatever) are found
> later in life they may or may not be re-installed correctly. They might not
> even be the ones that came with the instrument.
> 
>  Bob
> >>>
> >>> I am not sure if you are following me. On most (all??) HP kit I have
> >>> seen, there are 3 holes at each corner of the bottom, where is
> >>> possible to fit feet if one is going to use it on a desktop, rather
> >>> than a rack. This unit does not have those holes, so it would be
> >>> impossible to fit the usual HP feet on it.
> >>>
> >>> Looking around, I have 15 bits of HP kit,  all of which have holes in
> >>> the corner for feet. But this 58503A, with the Chinese box, does not
> >>> have the holes. I don't know whether the 85053A is supposed to have
> >>> them, or whether this is just a flaw in the design of the counterfeit.
> >>>
> >>> Dave
> >>> ___
> >>> time-nuts mailing list -- time-nuts@febo.com
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> >>
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Tom Van Baak

If any of you want me to post more photos let me know. I have several of every 
kind of HP/Agilent GPSDO product. And they are all genuine because I bought 
them a decade before the China/eBay/GPSDO business.

Right, I probably should have included some of HP's GPSDO products in the 
"hpclocks" photo shoot.

/tvb

> Where can I find the 58503A on leapsecond.com ? I don't see any GPS
> receivers in Tom's museum of HP clocks
> 
> http://leapsecond.com/hpclocks/
> 
> I'd like to find a picture of a *genuine* 58503A.



> What Bob suggested is just what I did.  The leapsecond photos happened to
> be the very first ones.  I was careless when typing and didn't think about
> gmail creating a link out of it.



> The instance pictured has the 16-char display option so it doesn't look
> like many of the images you find of the 58503A.
> 
> 


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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Hi

That display is a pretty hard part to fake. It’s not custom enough to be 
impossible to find, but I doubt it’s a stock part at your local market.

Bob

> On Dec 14, 2014, at 6:37 PM, Paul  wrote:
> 
> On Sun, Dec 14, 2014 at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
> drkir...@kirkbymicrowave.co.uk> wrote:
> 
>> I'd like to find a picture of a *genuine* 58503A.
>> 
> 
> The instance pictured has the 16-char display option so it doesn't look
> like many of the images you find of the 58503A.
> 
> 
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Joseph Gray

I have to watch what I'm typing a little closer. I meant to say "You
can't buy the parts this cheap."

Joe Gray
W5JG


On Sun, Dec 14, 2014 at 8:56 AM, Chris Albertson
 wrote:
> It's not worth making a PCB, not when you can buy the whole thing already
> assembled for $3 with free shipping.  I use these just as if they where a
> single chip and put them in a socket.  See eBay 141505833625 as an example.
>   Those holes are in 0.1 inch centers so you can figure out the size. (I
> get 1.3 inches long.)  direct link
> 
>
> I'll write up what I built.  It would be good to see the range of these.  I
> tried to make mine as simple an low cost as possible without regard to
> anything else.  Just to find the bottom line.  I doubt I would have met
> that gaol by using a bare AVR chip.  That is NOT simple because it requires
> so much more skill from the builder and with an entire working Arduino
> selling for $3 how much could you save?  Actually the chips on that $3
> board cost more than $3. (I don't even see how shipping from China can be
> that cheap.)
>
> On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor  wrote:
>>
>>
>> > On Dec 13, 2014, at 9:47 PM, Chris Albertson 
>> wrote:
>> >
>> > Actually I've added  some features to it like a 2 line by 16 character
>> LCD
>> > display and some status LEDs.  And I can log data to a computer via a USB
>> > cable so it is easy to plot data and it is using my more expansive mast
>> > mounted timing antenna.
>>
>>
>> Just in case any of you like reading Arduino code, for fun or functions to
>> copy-and-paste,
>> the code for my PCB that combines an ATMega328p with an Adafruit GPS and
>> 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at
>> GitHub.
>> It's not exactly, say, measuring oscillator cycles (yet... ) but it's
>> perhaps
>> a good introduction for someone who's never ever before used anything
>> Arduino.
>> (And now that I've done more PCBs with Cypress and FTDI chips, I wish I'd
>> put
>> that straight on my board instead of as a future daughterboard, but,
>> feature creep.)
>>
>> https://github.com/ptudor/jemma-clock
>>
>> PT
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>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Joseph Gray

I don't mean to "one up" Chris, but if you are looking for
inexpensive, I have bought the same Pro Mini from this seller for
$2.58. Like Chris says, you can't buy the parts this for this.

And if you need the 3.3 VDC version: http://www.ebay.com/itm/191182699659

I bought six of the Pro Mini's from this seller and every one tested
OK. I have also bought other items from this seller. I have no
complaints.

One thing to be aware of when looking for the Pro Mini boards. There
are at least three slightly different versions. At least one of them
has the serial programming pins on one end reversed. The board that
Chris and I have linked to are the exact same thing that SparkFun
sells. I believe it is the version 2.0 board. You can recognize it not
only by the serial programming pinout, but it also has the two pairs
of extra holes next to the chip. Those are A4/A5 and A6/A7.

Just as an aside, although it is often true that many of these Chinese
vendors sell ripoff copies of things, in this case, the Pro Mini
design is open source hardware, so it is legitimate for the Chinese or
anyone else to make and sell them.


Joe Gray
W5JG


On Sun, Dec 14, 2014 at 8:56 AM, Chris Albertson
 wrote:
> It's not worth making a PCB, not when you can buy the whole thing already
> assembled for $3 with free shipping.  I use these just as if they where a
> single chip and put them in a socket.  See eBay 141505833625 as an example.
>   Those holes are in 0.1 inch centers so you can figure out the size. (I
> get 1.3 inches long.)  direct link
> 
>
> I'll write up what I built.  It would be good to see the range of these.  I
> tried to make mine as simple an low cost as possible without regard to
> anything else.  Just to find the bottom line.  I doubt I would have met
> that gaol by using a bare AVR chip.  That is NOT simple because it requires
> so much more skill from the builder and with an entire working Arduino
> selling for $3 how much could you save?  Actually the chips on that $3
> board cost more than $3. (I don't even see how shipping from China can be
> that cheap.)
>
> On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor  wrote:
>>
>>
>> > On Dec 13, 2014, at 9:47 PM, Chris Albertson 
>> wrote:
>> >
>> > Actually I've added  some features to it like a 2 line by 16 character
>> LCD
>> > display and some status LEDs.  And I can log data to a computer via a USB
>> > cable so it is easy to plot data and it is using my more expansive mast
>> > mounted timing antenna.
>>
>>
>> Just in case any of you like reading Arduino code, for fun or functions to
>> copy-and-paste,
>> the code for my PCB that combines an ATMega328p with an Adafruit GPS and
>> 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at
>> GitHub.
>> It's not exactly, say, measuring oscillator cycles (yet... ) but it's
>> perhaps
>> a good introduction for someone who's never ever before used anything
>> Arduino.
>> (And now that I've done more PCBs with Cypress and FTDI chips, I wish I'd
>> put
>> that straight on my board instead of as a future daughterboard, but,
>> feature creep.)
>>
>> https://github.com/ptudor/jemma-clock
>>
>> PT
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>
>
> --
>
> Chris Albertson
> Redondo Beach, California
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Re: [time-nuts] Which First GPSDO to buy?

Hi

> On Dec 14, 2014, at 4:20 PM, Dave Daniel  wrote:
> 
> Thanks. See below:
> 
> On 12/14/2014 1:48 PM, Bob Camp wrote:
>> Hi
>> 
>> Ok so down to two choices:
>> 
>> 
>> LTE Lite:
>> 
>> 1) Comes up nice and fast (it’s a TCXO)
>> 
>> 2) Modern GPS receiver
>> 
>> 3) Good documentation
>> 
>> 4) Very low power
>> 
>> 5) Nice small size
> Good so far.
>> 
>> 6) Needs a box
> Boxes I have.

There’s also odd things like power connectors, again likely junk box items. 

>> 
>> 7) You know where to find Jackson Labs if there is a problem
>> 
>> 8) Getting a couple more in a couple years may be possible
> Also good.
>> 
>> Lucent:
>> 
>> 1) More accurate if you keep it on (it’s an OCXO)
>> 
>> 2) Spare parts set (= the second box) when you buy the pair
>> 
>> 3) Comes with a (clunky) enclosure
>> 
>> 4) Outputs are already isolated / buffered
> All good.
>> 5) Needs an antenna ($30 or so for a good one, $3 for a simple one)
> OK, doesn't sound too expensive.

The same $30 antenna will last a bit longer and mount a bit easier when used 
with most GPSDO’s. The exception are ones that put out 3.3V rather than 5V. 
There are a range of antennas out there to pick from. There are also antennas 
in the >= $100 range that you might consider for some applications. 

>> 6) Needs a power supply ($20 maybe less)
> I have a bunch of DC power supplies sitting in the storage closet. Or I can 
> build one. It's pretty simple.

The unit needs 18 to 36(?) V. That’s a lot of room for choices. The target 
supply was likely a “24V” battery bank. Take all the normal 12V numbers (charge 
/ discharge / dead battery/ smoke from the battery fast charge) and just double 
them.  I would not target < 22 V or > 30V out of the supply.  The internal 
brick is a regulated switcher, there is no need to hyper regulate the external 
supply. 

>> 
>> 7) Hook it up and check it out fast, there’s a 30 day warranty (which the 
>> guy does honor)
>> 
>> 8) Once this guy sells out, there may not be many more.
> Yes, I have been thinking about that. Maybe get one of these just to do it 
> before they are gone.

That’s why I keep harping on them

>> 
>> Both:
>> 
>> 1) You still need to mount the antenna somewhere
> The lab is one the second floor; It shouldn't be a problem to add it to the 
> breakout box going outside the room to the exterior.

You are after a clear view of the southern sky and at least due east / due 
west. A full sky view (360 degrees) would be nice. 

>> 
>> 2) You need to distribute the 10 MHz or 1 pps to your gear
> Yes, I haven't figured that out yet. But it will be fun.

You can do it for < $1 per channel. 

>> 
>> 3) With only one you will always be wondering “what if it’s wrong?”. Having 
>> two only confuses this situation ….
> One really needs three at a minimum. But acquiring three starts with 
> acquiring one.

Right, but consider that you are indeed buying the first of several. These 
things pop up and then go away. The Lucent is in that category. I have no idea 
of Jackson Lab’s plans for the LTE on eBay. That also *could* be a limited time 
deal. 

>> 
>> 4) Neither one lets you play much with the loop (filtering), both are pretty 
>> much optimum for the hardware as received
> I think this where building one oneself comes in. Or buying the Thunderbolt.

The T Bolt’s are pretty expensive these days. They also have a limited ability 
to modify things (but better than the other boxes). A home-brew is the only way 
to have full control. There’s no need to run out and get a TBolt at the prices 
they sell for these days. 

>> 
>> 5) Price wise not a lot of difference. Both will be $200-ish once you get 
>> them delivered and set up without the distribution stuff.
> Yes, and that is affordable while I am still working.

I suspect that one this guy sells out of the Lucent’s you will see them creep 
up in price. All the other Z38xx’s have done the same thing. Z3801’s once sold 
for what these are now selling for. TBolt’s sold for less. I would not count on 
Jackson labs having a fire sale. The LTE is a very good deal on a new 
commercial unit at the price it’s at. 

Unless the market changes a lot, you should be able to sell any of the surplus 
boxes in the future for more than what you paid for it (if it still works). If 
the LTE is a limited time deal, they will likely follow the same sort of price 
trajectory.  

>> 
>> What to do - get some of each :)
> Precisely my conclusion. I need to buy one of each. This is precisely how I 
> ended up with thirteen Tektronix oscilloscopes. It's the same process.
> 
> And right in the middle of Christmas gift-buying season.

Which could flush out the inventory of the Lucent boxes faster than one might 
think. They also could be around next June at the same price. I suppose there 
could be a massive inventory of them in China (water damage risk and all) and 
they could be $60 next June. 

> 
> A very useful summary. Thanks!

No problem.

Bob

> 
> DaveD
> 
> Bob
>>> On Dec 14, 2014, at

Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Paul

On Sun, Dec 14, 2014 at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> I'd like to find a picture of a *genuine* 58503A.
>

The instance pictured has the 16-char display option so it doesn't look
like many of the images you find of the 58503A.

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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Dave Daniel

Thanks. See below:

On 12/14/2014 1:48 PM, Bob Camp wrote:

Ok so down to two choices:

LTE Lite:

1) Comes up nice and fast (it’s a TCXO)

2) Modern GPS receiver

3) Good documentation

4) Very low power

5) Nice small size

Good so far.

6) Needs a box

Boxes I have.

7) You know where to find Jackson Labs if there is a problem

8) Getting a couple more in a couple years may be possible

Also good.

Lucent:

1) More accurate if you keep it on (it’s an OCXO)

2) Spare parts set (= the second box) when you buy the pair

3) Comes with a (clunky) enclosure

4) Outputs are already isolated / buffered

All good.

5) Needs an antenna ($30 or so for a good one, $3 for a simple one)

OK, doesn't sound too expensive.

6) Needs a power supply ($20 maybe less)
I have a bunch of DC power supplies sitting in the storage closet. Or I
can build one. It's pretty simple.

7) Hook it up and check it out fast, there’s a 30 day warranty (which the guy
does honor)

8) Once this guy sells out, there may not be many more.
Yes, I have been thinking about that. Maybe get one of these just to do
it before they are gone.

Both:

1) You still need to mount the antenna somewhere
The lab is one the second floor; It shouldn't be a problem to add it to
the breakout box going outside the room to the exterior.

2) You need to distribute the 10 MHz or 1 pps to your gear

Yes, I haven't figured that out yet. But it will be fun.

3) With only one you will always be wondering “what if it’s wrong?”. Having two
only confuses this situation ….
One really needs three at a minimum. But acquiring three starts with
acquiring one.

4) Neither one lets you play much with the loop (filtering), both are pretty
much optimum for the hardware as received

I think this where building one oneself comes in. Or buying the Thunderbolt.

5) Price wise not a lot of difference. Both will be $200-ish once you get them
delivered and set up without the distribution stuff.

Yes, and that is affordable while I am still working.

What to do - get some of each :)
Precisely my conclusion. I need to buy one of each. This is precisely
how I ended up with thirteen Tektronix oscilloscopes. It's the same process.

And right in the middle of Christmas gift-buying season.

A very useful summary. Thanks!

DaveD

Bob

On Dec 14, 2014, at 12:49 PM, Dave Daniel wrote:

Well, thanks, everyone, for the information. I appreciate the help.

First, I am presently not up to adding another project to my long list of
projects. I get whiplash every time I walk into the lab. Building a GPSDO sound
like fun. Perhaps down the line.

I figured I should add some information about myself: I am an electrical
engineer (currently employed) with a lot of digital/Verilog experience and a
fair bit of analog experience (but less than my digital experience) and quite a
bit of software experience, all of this from working for about thirty-eight
years on various embedded systems. Currently, I shy away from writing code just
because I don't enjoy it much and have done too much professionally. But I know
that eventually I will need to write code in my lab. Presently, I am in the
process of restoring some older ham radio gear, but I became sidetracked from
that by the necessity to repair a bunch of vintage test equipment which effort
has somehow taken on a life of it's own.

What I need right now is a frequency standard that is accurate enough to use as a reference for
things like calibrating test gear. I also want to "play" with one before I build one.
Just going through all of the educational material is a daunting task. I figured I'd combine an
interest with GPSDOs in general with a need for an accurate enough "standard" (I use the
term loosely here) to get some instruments calibrated.

Thanks again for all the information!

Cheers,
DaveD

I had forgotten about the LTE-lite; I should add that to the list of choices.
I'm tending towards either a 10 MHz version of that or the Lucent boxes.
On 12/14/2014 8:00 AM, Bob Camp wrote:

On Dec 14, 2014, at 12:47 AM, Chris Albertson wrote:

I tried to see just how simple, low cost and self contained I could make a
GPSDO. I started with the Lars Walenius design then removed everything I
could from it. I replace all the software with just a small loop with
about a dozen lines of code so it would be easy to understand.

My goal was to make something that could be built and tested using just
basic equipment. The question is of course "How do you know the unit is
making a 10 MHz signal if you don't already have a 10MHz reference to
compare it to?" Well you can assume that your 1PPS reference is accurate.

Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably
accurate over very long time spans. Over short spans the pps moves around a lot.

Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles
per each PPS.

If you do a tight lock (“EXACTLY”) against a GPS PPS that is moving +/

Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Hi

Every one that I found showing enough detail had the bumper with feet rather 
than the feet that clip into the case. A couple of power options are 
illustrated (DC and AC) with various option numbers attached.

Bob

> On Dec 14, 2014, at 5:25 PM, Alan Hochhalter  wrote:
> 
> What Bob suggested is just what I did.  The leapsecond photos happened to
> be the very first ones.  I was careless when typing and didn't think about
> gmail creating a link out of it.
> 
> Alan
> 
> On Sun, Dec 14, 2014 at 2:13 PM, Bob Camp  wrote:
>> 
>> Hi
>> 
>> If you type 58503A into Google, it will come up with a whole raft of
>> pictures of various angles on the device. Since none of them are from HP /
>> Symmetricom, any / all *could* be fakes. Logic suggests that at least 90%
>> of them are the real thing.
>> 
>> Bob
>> 
>> 
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Alan Hochhalter

What Bob suggested is just what I did.  The leapsecond photos happened to
be the very first ones.  I was careless when typing and didn't think about
gmail creating a link out of it.

Alan

On Sun, Dec 14, 2014 at 2:13 PM, Bob Camp  wrote:
>
> Hi
>
> If you type 58503A into Google, it will come up with a whole raft of
> pictures of various angles on the device. Since none of them are from HP /
> Symmetricom, any / all *could* be fakes. Logic suggests that at least 90%
> of them are the real thing.
>
> Bob
>
>
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

> 1) Downloaded ntp-4.2.6p5

If you are going to compile it (rather than use whatever comes with your 
system), please use the Release Candidate version from:
  http://support.ntp.org/bin/view/Main/SoftwareDownloads

[Anybody else willing to help...  This is your chance.  If you find bugs, 
submit a bug report and/or poke me off list.]


> and also the directory /dev/fd

That's something else.  I don't know what they are.  My guess would be 
something associated with the file system.


> That I am not sure how to configure ntp.conf - a case of RTFM.

It's probably as simple as adding
  server 127.127.26.0
but read the driver26.html page

You also need something like:
  ln -s /dev/ttyS0 /dev/hpgps0


> How do you reboot - apart from of course powering the thing off?

Yes.  Power cycle.

> E-101>  :PTIME:TCODE?
> T220141214123441337

You can sanity check the UTC/GPS by eyeball.  They are 16 seconds apart.

You can clear the E-101 (and get back to scpi) by sending:
  *CLS



> I know those commands, although I don't recommend "reboot" - it is less
> clean than init 6. I assumed that that Hal Murry's "reboot" was meant to be
> the GPS receiver, not the Solaris computer, but maybe I mis-understood. 

Yes.  Power cycle the GPSDO.  At least on the Z3801A, it's stored in flash.  
You only have to do it once.

I think there is a software command to reboot.  I don't have it handy.  
Mostly, I work from the Z3801A manual.  A few things don't work on the 
KS-24361.


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Re: [time-nuts] Set time on Solaris computer from HP 58503A

Hi

> On Dec 14, 2014, at 4:26 PM, Hal Murray  wrote:
> 
> 
> gign...@gmail.com said:
>> Based on my recent testing - including Solaris - you will be better off with
>> the Internet unless your USB adapter is far better behaved than the several
>> I have here 
> 
> That depends,  (TM)
> 
> How good/bad is your network connection?  Mine gets over 3 seconds of queuing 
> delays.  I challenge anybody to find a USB device that bad.
> 
> There are only 2 or 3 significant vendors of USB-serial chips.  I think they 
> are reasonably well supported by all major OSes.
> 
> USB is polled, so interrupt latency turns into polling latency.  I think the 
> polling cycle is 1 ms for slow things like serial ports.  

On at least some (= the ones I’ve seen) of the serial devices, they will 
continue to buffer if they have a character coming in. Put another way, a 
string sent at 19.2 Kbaud will likely transfer as a block rather than a 
character at a time. Is this  at the bus or the driver level? - who knows. The 
result (in Linux / Win-dooze / or OS-X) is that data comes in in bursts. 

> Maybe 1/4 ms for 
> faster things like disks.  At the system level, faster polling means more 
> overhead and slower polling means bigger buffers.
> 
> Many of the low cost GPS units use the SiRF chips.  They have a wander of 
> ~100 ms.  I said wander rather than jitter because it's very slow as in 
> hours.  You can't filter it out with a 10 or 100 second sample.

.. as in a pps output is not  necessarily  a *useful* pps output. Only useful 
outputs count. We’ve been over the why and the how of chips that put out pps’s 
way late a number of times. Simple answer - it didn’t matter in the firmware 
design spec. 

Bob

> 
> The old Garmin GPS-18-USB (not 18x) units had pretty good timing.  No wander. 
> Unfortunately, they weren't very sensitive.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

Eds
Right I did see it used to turn square waves into sine waves. I will have
to try that.
But I am very happy with it even as a simple transformer. Thats what
surprised me something that goes nicely all the way down below 60 KHz. I
have to tell you I have been using lots of things that I have found for 60
and 100 Khz. This offers me some consistency with actual documentation.
Its hard to find LF things these days. Beats un-soldering from a board also.

Bob granted these can be used for twisted pair. Unshielded also. What about
radiation at 5 or 10 Mhz. Granted there is shielded twisted pairs.
Regards
Paul
WB8TSL

On Sun, Dec 14, 2014 at 4:20 PM, Jim Lux  wrote:
>
> On 12/14/14, 10:41 AM, paul swed wrote:
>
>> Well with zero effort the spec sheet. Bob indeed there are common mode
>> chokes in them. Jeeze a lot in 1 package along with center taps.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>
> I've seen a lot of MiniCircuits BNC 10.7 MHz BPFs used in equipment racks
> over the years as a sort of "get rid of trash" filter (at least I'm sure
> that's what the person who bought them thought).  Not so hot in terms of
> phase vs temperature (elliptic filter, 2 MHz wide, centered at 10.7), but
> probably pretty good at knocking down harmonics and such.
>
> BBP-10.7+ ... $41 each.
> http://www.minicircuits.com/pdfs/BBP-10.7+.pdf
>
>
> Interestingly, only 26 dB rejection at 20 MHz. Must be in the middle of
> the first "bounce" of the response..
>
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Re: [time-nuts] Set time on Solaris computer from HP 58503A


gign...@gmail.com said:
> Based on my recent testing - including Solaris - you will be better off with
> the Internet unless your USB adapter is far better behaved than the several
> I have here 

That depends,  (TM)

How good/bad is your network connection?  Mine gets over 3 seconds of queuing 
delays.  I challenge anybody to find a USB device that bad.

There are only 2 or 3 significant vendors of USB-serial chips.  I think they 
are reasonably well supported by all major OSes.

USB is polled, so interrupt latency turns into polling latency.  I think the 
polling cycle is 1 ms for slow things like serial ports.  Maybe 1/4 ms for 
faster things like disks.  At the system level, faster polling means more 
overhead and slower polling means bigger buffers.

Many of the low cost GPS units use the SiRF chips.  They have a wander of 
~100 ms.  I said wander rather than jitter because it's very slow as in 
hours.  You can't filter it out with a 10 or 100 second sample.

The old Garmin GPS-18-USB (not 18x) units had pretty good timing.  No wander. 
 Unfortunately, they weren't very sensitive.


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Re: [time-nuts] What sort of oscillator is this?

Hi

> On Dec 14, 2014, at 4:14 PM, Jim Lux  wrote:
> 
> On 9/28/14, 7:55 AM, Richard Karlquist wrote:
>> 
>>> I find it odd that an instrument that probably cost $50,000 when new did
>>> not have a TCXO as standard,  and perhaps an oven as an option.

A *lot* of places that had this stuff ran it out of a frequency standard 
distribution system 100% of the time. If you saw “TCXO” in the specs, the first 
thing to do was call the HP sales guy and ask if you could get a discount on 
one that had a crystal instead….. 

>>> 
>>> But I think HP did this sort of thing a lot. Something that would have
>>> cost
>>> very little to add, became an expensive option. In some cases these
>>> expensive options are nothing more than enabling a bit of software,
>>> although the R&D cost of the software is probably a lot more than the
>>> hardware cost of adding a better oscillator.
> 
> 
> 
> There's also a difference between the "kind of oscillator" in the 
> instrument.. Rick can probably tell us for sure, but I've heard it rumored 
> that counters typically got an oscillator optimized for accuracy and low 
> aging, but not necessarily so hot for phase noise, while synthesizers and 
> spectrum analyzers would get a good phase noise oscillator, but maybe with 
> more aging, figuring that the "cal lab" at the customer's facility would 
> reset the frequency every year anyway.

HP bought a *lot* of oscillators on the open market from a wide range of 
suppliers. They very much customized the spec’s on these oscillators to match 
what they felt were the needs of the target market for this or that piece of 
gear. 

> 
> I'm sure there's also some aspects of whether customers were more likely to 
> have a house standard or leave the equipment powered on vs connected to power 
> (so that a "standby mode" could keep the oscillator powered on).

Back in the 80’s the federal government / DOD in the US issues an edict that 
gear could not be on overnight . Oddly enough they were a pretty large customer 
for this sort of gear. That did indeed impact the specs on the oscillators. In 
some cases the practice flowed down to contractor sites. That just increased 
the size of the market with on/off cycles. 

> 
> And that in turn was somewhat determined by whether the equipment was 
> "portable" (has a handle, like a 8563 spectrum analyzer) or "rack/bench" 
> (like a 8663 signal generator).  The portable units aren't going to be 
> powered on all the time, so you want something that is "ready to go" within a 
> short time after plugging it in.

Some of that gear got low powered OCXO’s Back in the days when manuals with 
schematics were common it was pretty easy to spot this sort of thing. 

Bob

> 
> 
> 
>> I worked for the HP Santa Clara Division for 19 years.  The reason
>> why a customer would NOT want a precision oscillator in a high end
>> instrument would be that he was going to use a "house standard".
> 
>> We of course made OCXO's at SCD and "sold" them to other HP divisions.
>> It would not be impossible for a division to use a TCXO, but it would
>> be out of character given that we transferred 10811's at "cost", which
>> was then about $400.
> 
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Re: [time-nuts] tyco electronics A1025


kb...@n1k.org said:
> My guess is that there is no PPS out of the device. It would be very unusual
> if there was. Finding the NEMA output pin should be possible with an
> oscilloscope. At that point, a simple serial connection to the server is
> about all you need. Bring up the NEMA driver and it is running.

You may need an inverter in the serial path.

I'd expect there to be a PPS signal coming out of a GPS module.  It is often 
left unconnected, or connected to a LED.


-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

2014-12-14 Thread Jim Lux


On 12/14/14, 10:41 AM, paul swed wrote:

Well with zero effort the spec sheet. Bob indeed there are common mode
chokes in them. Jeeze a lot in 1 package along with center taps.
Regards
Paul
WB8TSL




I've seen a lot of MiniCircuits BNC 10.7 MHz BPFs used in equipment 
racks over the years as a sort of "get rid of trash" filter (at least 
I'm sure that's what the person who bought them thought).  Not so hot in 
terms of phase vs temperature (elliptic filter, 2 MHz wide, centered at 
10.7), but probably pretty good at knocking down harmonics and such.


BBP-10.7+ ... $41 each.
http://www.minicircuits.com/pdfs/BBP-10.7+.pdf


Interestingly, only 26 dB rejection at 20 MHz. Must be in the middle of 
the first "bounce" of the response..

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Re: [time-nuts] What sort of oscillator is this?

2014-12-14 Thread Jim Lux


On 9/28/14, 7:55 AM, Richard Karlquist wrote:



I find it odd that an instrument that probably cost $50,000 when new did
not have a TCXO as standard,  and perhaps an oven as an option.

But I think HP did this sort of thing a lot. Something that would have
cost
very little to add, became an expensive option. In some cases these
expensive options are nothing more than enabling a bit of software,
although the R&D cost of the software is probably a lot more than the
hardware cost of adding a better oscillator.




There's also a difference between the "kind of oscillator" in the 
instrument.. Rick can probably tell us for sure, but I've heard it 
rumored that counters typically got an oscillator optimized for accuracy 
and low aging, but not necessarily so hot for phase noise, while 
synthesizers and spectrum analyzers would get a good phase noise 
oscillator, but maybe with more aging, figuring that the "cal lab" at 
the customer's facility would reset the frequency every year anyway.


I'm sure there's also some aspects of whether customers were more likely 
to have a house standard or leave the equipment powered on vs connected 
to power (so that a "standby mode" could keep the oscillator powered on).


And that in turn was somewhat determined by whether the equipment was 
"portable" (has a handle, like a 8563 spectrum analyzer) or "rack/bench" 
(like a 8663 signal generator).  The portable units aren't going to be 
powered on all the time, so you want something that is "ready to go" 
within a short time after plugging it in.





I worked for the HP Santa Clara Division for 19 years.  The reason
why a customer would NOT want a precision oscillator in a high end
instrument would be that he was going to use a "house standard".



We of course made OCXO's at SCD and "sold" them to other HP divisions.
It would not be impossible for a division to use a TCXO, but it would
be out of character given that we transferred 10811's at "cost", which
was then about $400.


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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

If you type 58503A into Google, it will come up with a whole raft of pictures 
of various angles on the device. Since none of them are from HP / Symmetricom, 
any / all *could* be fakes. Logic suggests that at least 90% of them are the 
real thing. 

Bob

> On Dec 14, 2014, at 4:08 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, 
> UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
> 
> 
> On 14 December 2014 at 20:07, Alan Hochhalter  wrote:
>> The 58503A in the picture on leapsecond.com looks very similar to my older
>> 34401A DVM which doesn't have separate feet.
> 
> Where can I find the 58503A on leapsecond.com ? I don't see any GPS
> receivers in Tom's museum of HP clocks
> 
> http://leapsecond.com/hpclocks/
> 
> I'd like to find a picture of a *genuine* 58503A.
> 
> Dave
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)

On 14 December 2014 at 20:07, Alan Hochhalter  wrote:
> The 58503A in the picture on leapsecond.com looks very similar to my older
> 34401A DVM which doesn't have separate feet.

Where can I find the 58503A on leapsecond.com ? I don't see any GPS
receivers in Tom's museum of HP clocks

http://leapsecond.com/hpclocks/

I'd like to find a picture of a *genuine* 58503A.

Dave
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Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

2014-12-14 Thread Dave M

The Pulse Engineering PE-68025 module from Electronic Goldmine 
(http://www.goldmine-elec-products.com/prodinfo.asp?number=G17078) has 
common mode chokes and LPFs on both Tx and Rx lines.  On clearance for $1.00 
each.  Datasheet is at 
http://www.datasheetarchive.com/dlmain/Datasheets-9/DSA-179465.pdf


Cheers,
Dave M



ed breya wrote:

I investigated those 10b-t isolation modules a while back, and have
saved every module from every network card and router/hub/switch that
I have junked out. The very old 10b-t stuff is the best for getting
LPFs and individual per-channel (port) type parts. When they started
making 10/100 Mb/sec, the 17 MHz filters were eliminated, and the
parts got integrated to ever-higher levels, with multiple channels in
each module.

You have to be able to find the data sheets to be sure of what's in
them - some are transformers only, and some also have LPFs and
common-mode chokes in various combinations. The filter sections can
also be cascaded for even sharper cutoff, but there's quite a bit of
crosstalk, so a lot of higher frequency stuff gets through,
especially above 100 MHz, so it's mostly effective from around 20-100
MHz. It has been mentioned before that very sharp filters will tend
to have more phase noise (phase shift with temperature/component
variations), but the negative effects depend on the application - I
only care about frequency reference distribution to SAs and
synthesizers, for example, so I don't worry about exact phase and
timing between equipment.

There is a nice variety of magnetic parts from all types of network
devices, including DSL an ISDN.

Ed




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Re: [time-nuts] Homebrew frequency counter, need help


Hi Bob,

On 12/14/2014 06:00 PM, Bob Camp wrote:

Hi


On Dec 14, 2014, at 11:36 AM, Magnus Danielson  
wrote:



On 12/12/2014 06:15 PM, Bob Camp wrote:

Hi


On Dec 12, 2014, at 11:44 AM, Li Ang  wrote:

Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
ref=5650 case.


In the “both same (5650 / 5650) case” your linear regression filtering is 
faking you out a bit. The SR620 counter has exactly this same issue. That’s 
probably for the same reason. It’s a fine test to see if you have various 
problems under control. It’s not a perfect way to estimate the number of digits 
you will get on a real measurement. Using two independent sources is a better 
way to do that.

When you have two identical signals, the TDC noise is the main issue. All the 
edges are arriving in the same relation to each other (same timing). The linear 
regression is (obviously) good at suppressing the sort of noise the TDC has. 
With two independent signals the noise is more complex. The edges arrive at 
various times relative to each other. More things contribute to the total 
noise. The linear regression is having a harder time suppressing that sort of 
noise. In some cases (as you observed) the linear regression is actually making 
things worse.

If Magnus was here, he would be tossing empty beer bottles at me and saying — 
see Bob, sqrt(N) doesn’t always work ….


Indeed, except I would not be tossing empty beer bottles at you, I might 
jokingly attempt do, but never actually throw it. One has to realize that the 
quantization noise of the TIC may seem to process as if it where white phase 
noise, but it isn't random noise, it is a systematic noise and if you fool 
around with the systematics is may work for you or against you.

I do consider to pass another bottle of good beer to Bob for good behavior. :)


…. as long as we don’t start tossing kegs at each other, I consider myself 
lucky :)


Maybe empty, the beer will be so hard to tap if you throw full kegs, 
even if full kegs have better impact to get the point through. :)





The filtering process used does need to be adapted to the noise of the total 
system.


It's one of the forgotten parameters, and I've even seen good Sam Stein stand up and say 
"we used to do this wrong" on the same point, you need to publish and consider 
the bandwidth of your processing, as it *will* affect the ADEV plot (but only MDEV and 
TDEV somewhat).



Since I really want to reduce the noise, what is the best test set you
suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2
OCXO,


If the MV89’s are in good working condition, they are the best thing to 
compare.The have the best ADEV of the group you have available I would check 
them for output level and stability before I trusted them. There are a lot of 
defective parts on the market. People get some, sort them and sell the bad 
ones. The bad ones just keep getting re-sold again and again … My guess is that 
they were good parts at one time and they got damaged when pulled off boards. 
If you use them, keep them on power at all times. Any OCXO will do better if 
you run it that way.


In order to test if systematics is messing badly with you, measure the ADEV of 
the oscillator as it is steered (and stabilized) to a number of different 
frequencies. For larger offsets to the counter reference, multiple beatings 
occurs within the regression interval. You want that number to be an even 
number of beats, or the beat count to be so large that the phase of the last 
beat does not care. Linear regression helps out, as it weighs out the outermost 
measures compared to the central one, making the beating at the beginning and 
end not care as much.

These are *systematic* noise effects, and as you play around with systematics 
and processing, you might have the systematics works for or against you, but at 
the same time, the random noise you try to measure will suffer the processing 
filtering, and you need to recall that. If you balance these properly, you can 
make good and correct measurements, it's just that few do.

Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises 
as they show up there should be estimated separately and removed from the 
random noise estimates. They have *way* different behaviors.


… and this is where it gets complicated. I would toss in the Hadamard deviation 
into that mix as well.


The Hadamard deviation is a great tool as it is not sensitive to linear 
frequency drift as Allan deviation is. This would help to remove the 
systematic effect, just as a quadratic curve-fitting of the raw-data and 
ADEV of the residual.


Modified Hadamard deviation (MHDEV) is a good replacement for MDEV, with 
the same properties for drift. Similarly will Time Hadarmard Deviation 
(THDEV) replace TDEV. However, for longer taus you want better 
processing, so therefore you want to consider the TOTAL set of 
deviations, such that confidence intervals is better.



If

Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Hi


> On Dec 14, 2014, at 3:50 PM, Scott McGrath  wrote:
> 
> Much of the Malaysian Agilent gear uses this style of case with a wraparound 
> bumper in place of the system II feet and feet are removed when gear is rack 
> mounted.
> 
> One of my best surplus buys ever was a huge crate of mixed mounting hardware 
> feet / rack flanges etc I've been using that box o stuff for 10 years

Somewhere there’s a building full of gear all of which is missing it’s feet and 
bumpers …

You are lucky to have found that box. In most cases they get tossed out with 
the trash. The same is true of many of the fancy i/o cables, they get put into 
the copper recycle pile and are gone…

Bob

> 
> Content by Scott
> Typos by Siri
> 
>> On Dec 14, 2014, at 3:09 PM, Bob Camp  wrote:
>> 
>> Hi
>> 
>> The desktop version (with handle) used the rubber “bumper” wrap around for 
>> feet. The bumpers got pulled when they were rack mounted. The ones that got 
>> put back on may or may not be identical to the originals. That’s a very 
>> normal part of the surplus process. The 100% correct HP original case on the 
>> box as HP built it did not use the clip on feet. 
>> 
>> The reason for this is pretty simple. The Z3801 / Z3805 came before the 
>> “instrument” versions of the same products. The internal case structure is 
>> same/ same. The instrument simply gets a gray sheet metal jacket that fits 
>> around the Z38xx box. That’s the way HP designed it. Since its just a 
>> jacket, it gets feet as part of the bumpers. Most of these (likely 99%) got 
>> rack mounted and the feet / bumpers were tossed. I have a *lot* of very 
>> legit surplus HP gear that did not come with feet or bumpers. 
>> 
>> Bob
>> 
>>> On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>>>  wrote:
>>> 
>>> On 14 December 2014 at 19:32, Bob Camp  wrote:
>>> 
> There are not the usual 3 holes underneath where feet go.
 
 I understand that they are different. The problem is the same though. 
 Pulling a box in and out of a rack with feet or bumpers on it is a pain. 
 They often get “lost” early in the instrument’s life. Often it’s a 
 standard process on all gear as it comes into the facility.  All of the 
 un-needed bits and pieces go into a big pile. When the feet (or whatever) 
 are found later in life they may or may not be re-installed correctly. 
 They might not even be the ones that came with the instrument.
 
 Bob
>>> 
>>> I am not sure if you are following me. On most (all??) HP kit I have
>>> seen, there are 3 holes at each corner of the bottom, where is
>>> possible to fit feet if one is going to use it on a desktop, rather
>>> than a rack. This unit does not have those holes, so it would be
>>> impossible to fit the usual HP feet on it.
>>> 
>>> Looking around, I have 15 bits of HP kit,  all of which have holes in
>>> the corner for feet. But this 58503A, with the Chinese box, does not
>>> have the holes. I don't know whether the 85053A is supposed to have
>>> them, or whether this is just a flaw in the design of the counterfeit.
>>> 
>>> Dave
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Re: [time-nuts] Linear voltage regulator hints...

Hi

What you actually have tested (in this case) is temperature rate of change. The 
parts involved are designed for a rate change in the 0.1 to 1C / minute range. 
Taking them way outside that range leads to unpredictable results. In the case 
of the GPS, it goes into some sort of failure mode. It’s no different that 
taking an IC that’s rated to 125C and seeing what happens at 300C. That’s 
outside it’s design range and odd things will happen. 

Bob

> On Dec 14, 2014, at 3:38 PM, d...@irtelemetrics.com wrote:
> 
>Yeah, I guess it's all relative. :) I do agree it is a HUGE change 
> compared to what the GPS should see in normal operation. The same blast of 
> air can be pointed at the GPSDO board for 20 seconds and see no change. On 
> high at the oscillator for 60+ seconds with no change is apparent. The GPS is 
> what responds. 
> Does this mean anthing? It's well beyond what the GPS should see, so I doubt 
> it. Is the GPS the most sensitive part in the system right now? Maybe. But, 
> Bob could be correct that the OCXO is the sensitive part.  The PWM DAC used 
> to respond like the GPS to temp changes. Using 'heat and watch' found it. 
> Addressing it has cut overall temp sensitivity down by more than a factor of 
> 10. I consider that a measurable change. Any temp sensitivity left is really 
> small, and wonder if it can be addressed with the hardware and tools at hand. 
> My gut feeling is you are right about the GPS time base being sensitive. It 
> would be fun to hack into this and try clocking it off the OCXO, but I'm not 
> there yet! :)   I might try some good old 'overkill' and put the GPS in it's 
> own heavy aluminum box. It's been a thought for a while, and should address 
> the thermal integration and time constants you referred to. For this system, 
> it's doubtful that an underground bomb proof bunker is needed. ;) 
> I'd like to learn more about what testing could be done and would be more 
> than happy to discuss this off line, if anyone is interested.  This thread 
> has probably out lived it's useful life.   
> Thanks,
> Dan
>  
>  
>  
> > LOL. A couple of seconds of warm air at 15C above ambient is a HUGE
> > temperature transient for any sensitive electronics, especially
> > anything with an oscillator. I would venture a guess that the lion's
> > share of the drift you see is the GPS time base shooting
> > off-frequency, but there are probably other effects, too (voltage
> > regulators, to name just one).  >
> > To me, a "little change" in this context might be blowing one warm
> > breath toward the GPS unit from 18" away and seeing what happens over
> > the next minute or two.  >
> > But the GPS temperature sensitivity shouldn't be a big factor in
> > actual use. The GPS should be thermally isolated from anything that
> > changes temperature rapidly, and enclosed such that external
> > temperature changes are integrated over at least tens of
> > minutes. Then, the inside of the enclosure will reach its own
> > thermal equilibrium and any external changes will be slowed enough to
> > be tracked out by the GPS discipline. My recommendation would be to
> > put it in a cast aluminum box (search the archives for "cast aluminum
> > box"), but there are others who think you need to build a two foot
> > cube out of cinderblocks and fire brick against a wall in the deepest
> > external corner of your basement.  >
> > OR, if my suspicion is correct that the temperature sensitivity is
> > mostly the GPS time base, figure out a way to kludge the GPS to
> > accept the disciplined OCXO as its time base.  >
> > Best regards,
> >
> > Charles
> 
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Re: [time-nuts] Meaning of "SS" on status screen from 58503A




On 12/14/2014 08:57 PM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:

On 14 December 2014 at 19:52, Bob Camp  wrote:

Hi

SS is signal strength. There is a setting somewhere buried deep in the SCPI to 
switch the display units.

Bob


I guessed SS probably was signal strength, but what values are good
and bad? There's nothing in any manual I can find that mentions SS on
the 58503A. I can't find any SCPI command that is supposed to switch
the display units.


The 58503 manual gives this detail:

C/N (58503B)

indicates the carrier-to-noise ratio of the received the signal, from a 
range of 26 to 55. A ratio below 35 is a weak signal that may not be 
acquired by the Receiver.


SS (59551A)

indicates the strength of the signal, from a range of 0 to 255. A signal 
strength of 20 to 30 is a weak signal that may not be acquired by the 
Receiver.


I suspect that the SS was upgraded to C/N in the development.

Cheers,
Magnus
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Scott McGrath

Much of the Malaysian Agilent gear uses this style of case with a wraparound 
bumper in place of the system II feet and feet are removed when gear is rack 
mounted.

One of my best surplus buys ever was a huge crate of mixed mounting hardware 
feet / rack flanges etc I've been using that box o stuff for 10 years

Content by Scott
Typos by Siri

> On Dec 14, 2014, at 3:09 PM, Bob Camp  wrote:
> 
> Hi
> 
> The desktop version (with handle) used the rubber “bumper” wrap around for 
> feet. The bumpers got pulled when they were rack mounted. The ones that got 
> put back on may or may not be identical to the originals. That’s a very 
> normal part of the surplus process. The 100% correct HP original case on the 
> box as HP built it did not use the clip on feet. 
> 
> The reason for this is pretty simple. The Z3801 / Z3805 came before the 
> “instrument” versions of the same products. The internal case structure is 
> same/ same. The instrument simply gets a gray sheet metal jacket that fits 
> around the Z38xx box. That’s the way HP designed it. Since its just a jacket, 
> it gets feet as part of the bumpers. Most of these (likely 99%) got rack 
> mounted and the feet / bumpers were tossed. I have a *lot* of very legit 
> surplus HP gear that did not come with feet or bumpers. 
> 
> Bob
> 
>> On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>>  wrote:
>> 
>> On 14 December 2014 at 19:32, Bob Camp  wrote:
>> 
 There are not the usual 3 holes underneath where feet go.
>>> 
>>> I understand that they are different. The problem is the same though. 
>>> Pulling a box in and out of a rack with feet or bumpers on it is a pain. 
>>> They often get “lost” early in the instrument’s life. Often it’s a standard 
>>> process on all gear as it comes into the facility.  All of the un-needed 
>>> bits and pieces go into a big pile. When the feet (or whatever) are found 
>>> later in life they may or may not be re-installed correctly. They might not 
>>> even be the ones that came with the instrument.
>>> 
>>> Bob
>> 
>> I am not sure if you are following me. On most (all??) HP kit I have
>> seen, there are 3 holes at each corner of the bottom, where is
>> possible to fit feet if one is going to use it on a desktop, rather
>> than a rack. This unit does not have those holes, so it would be
>> impossible to fit the usual HP feet on it.
>> 
>> Looking around, I have 15 bits of HP kit,  all of which have holes in
>> the corner for feet. But this 58503A, with the Chinese box, does not
>> have the holes. I don't know whether the 85053A is supposed to have
>> them, or whether this is just a flaw in the design of the counterfeit.
>> 
>> Dave
>> ___
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

Ok so down to two choices:


LTE Lite:

1) Comes up nice and fast (it’s a TCXO)

2) Modern GPS receiver 

3) Good documentation 

4) Very low power 

5) Nice small size

6) Needs a box

7) You know where to find Jackson Labs if there is a problem

8) Getting a couple more in a couple years may be possible

Lucent:

1) More accurate if you keep it on (it’s an OCXO)

2) Spare parts set (= the second box) when you buy the pair

3) Comes with a (clunky) enclosure 

4) Outputs are already isolated / buffered

5) Needs an antenna ($30 or so for a good one, $3 for a simple one)

6) Needs a power supply ($20 maybe less)

7) Hook it up and check it out fast, there’s a 30 day warranty (which the guy 
does honor)

8) Once this guy sells out, there may not be many more.

Both:

1) You still need to mount the antenna somewhere 

2) You need to distribute the 10 MHz or 1 pps to your gear

3) With only one you will always be wondering “what if it’s wrong?”. Having two 
only confuses this situation …. 

4) Neither one lets you play much with the loop (filtering), both are pretty 
much optimum for the hardware as received 

5) Price wise not a lot of difference. Both will be $200-ish once you get them 
delivered and set up without the distribution stuff.

What to do - get some of each :)

Bob






> On Dec 14, 2014, at 12:49 PM, Dave Daniel  wrote:
> 
> Well, thanks, everyone, for the information. I appreciate the help.
> 
> First, I am presently not up to adding another project to my long list of 
> projects. I get whiplash every time I walk into the lab. Building a GPSDO 
> sound like fun. Perhaps down the line.
> 
> I figured I should add some information about myself: I am an electrical 
> engineer (currently employed) with a lot of digital/Verilog experience and a 
> fair bit of analog experience (but less than my digital experience) and quite 
> a bit of software experience, all of this from working for about thirty-eight 
> years on various embedded systems. Currently, I shy away from writing code 
> just because I don't enjoy it much and have done too much professionally. But 
> I know that eventually I will need to write code in my lab. Presently, I am 
> in the process of restoring some older ham radio gear, but I became 
> sidetracked from that by the necessity to repair a bunch of vintage test 
> equipment which effort has somehow taken on a life of it's own.
> 
> What I need right now is a frequency standard that is accurate enough to use 
> as a reference for things like calibrating test gear. I also want to "play" 
> with one before I build one. Just going through all of the educational 
> material is a daunting task. I figured I'd combine an interest with GPSDOs in 
> general with a need for an accurate enough "standard" (I use the term loosely 
> here) to get some instruments calibrated.
> 
> Thanks again for all the information!
> 
> Cheers,
> DaveD
> 
> I had forgotten about the LTE-lite; I should add that to the list of choices. 
> I'm tending towards either a 10 MHz version of that or the Lucent boxes.
> On 12/14/2014 8:00 AM, Bob Camp wrote:
>> Hi
>> 
>>> On Dec 14, 2014, at 12:47 AM, Chris Albertson  
>>> wrote:
>>> 
>>> I tried to see just how simple, low cost and self contained I could make a
>>> GPSDO.  I started with the Lars Walenius design then removed everything I
>>> could from it.  I replace all the software with just a small loop with
>>> about a dozen lines of code so it would be easy to understand.
>>> 
>>> My goal was to make something that could be built and tested using just
>>> basic equipment.  The question is of course "How do you know the unit is
>>> making a 10 MHz signal if you don't already have a 10MHz reference to
>>> compare it to?"  Well you can assume that your 1PPS reference is accurate.
>> Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably 
>> accurate over very long time spans. Over short spans the pps moves around a 
>> lot.
>> 
>>> Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles
>>> per each PPS.
>> If you do a tight lock (“EXACTLY”)  against a GPS PPS that is moving +/- 10 
>> ns, your frequency will swing +/- 1x10^-8 every second
>> 
>>> Count both for a few days and verify the ratio remains at
>>> ten million to one, exactly.
>> Ok, that’s looking at the long term where GPS is indeed accurate. That’s the 
>> easy part on any GPSDO design.
>> 
>>>  I ran mine for about 8 weeks and it stays at
>>> the desired ratio.I know this is not a perfect test because it could
>>> have been running at zero hertz for 30 seconds and then 20MHz for 30
>>> seconds but I assume the OCXO is better than that.   The point is that once
>>> you have the GPS working you DO have a  pretty good 1Hz reference.
>> Well, not quite so fast. You just jumped over a massive amount of work that 
>> normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every 
>> second would pass your test. (which is not in any way to say that y

Re: [time-nuts] Meaning of "SS" on status screen from 58503A

On 14 December 2014 at 20:25, Bob Camp  wrote:
> Hi
>
> http://www.cnssys.com/files/M12+UsersGuide.pdf

Thank you.

> On page 46 there is a pretty good chart for signal strength to c/n. The chart 
> for the Motoroal GPS module in yours should be quite similar.
>
> If there is no SCPI then it’s a “feature enhancement” in a later version of 
> the firmware.

OK

> Are you looking at the data with a terminal program or via Z38xx? If it’s 
> through Z38xx the program is probably converting things for you. From the 
> screen shot it looks like your are running a terminal.

A terminal program on my unix box (Sun Blade 2000 running Solaris 10).

I have also just started to open the port using the "open" command and
send it data via the "write" command. Next step is to read it of
course. Then I can collect data over time, and log it.

Dave
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Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

2014-12-14 Thread ed breya

I investigated those 10b-t isolation modules a while back, and have 
saved every module from every network card and router/hub/switch that 
I have junked out. The very old 10b-t stuff is the best for getting 
LPFs and individual per-channel (port) type parts. When they started 
making 10/100 Mb/sec, the 17 MHz filters were eliminated, and the 
parts got integrated to ever-higher levels, with multiple channels in 
each module.


You have to be able to find the data sheets to be sure of what's in 
them - some are transformers only, and some also have LPFs and 
common-mode chokes in various combinations. The filter sections can 
also be cascaded for even sharper cutoff, but there's quite a bit of 
crosstalk, so a lot of higher frequency stuff gets through, 
especially above 100 MHz, so it's mostly effective from around 20-100 
MHz. It has been mentioned before that very sharp filters will tend 
to have more phase noise (phase shift with temperature/component 
variations), but the negative effects depend on the application - I 
only care about frequency reference distribution to SAs and 
synthesizers, for example, so I don't worry about exact phase and 
timing between equipment.


There is a nice variety of magnetic parts from all types of network 
devices, including DSL an ISDN.


Ed

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Re: [time-nuts] Linear voltage regulator hints...

2014-12-14 Thread dan

Yeah, I guess it's all relative. :) I do agree it is a HUGE 
change compared to what the GPS should see in normal operation. The 
same blast of air can be pointed at the GPSDO board for 20 seconds and 
see no change. On high at the oscillator for 60+ seconds with no change 
is apparent. The GPS is what responds. 
 Does this mean anthing? It's well beyond what the GPS should see, so 
I doubt it. Is the GPS the most sensitive part in the system right now? 
Maybe. But, Bob could be correct that the OCXO is the sensitive part. 
 The PWM DAC used to respond like the GPS to temp changes. Using 'heat 
and watch' found it. Addressing it has cut overall temp sensitivity 
down by more than a factor of 10. I consider that a measurable 
change. Any temp sensitivity left is really small, and wonder if it 
can be addressed with the hardware and tools at hand. 
 My gut feeling is you are right about the GPS time base being 
sensitive. It would be fun to hack into this and try clocking it off 
the OCXO, but I'm not there yet! :)   I might try some good old 
'overkill' and put the GPS in it's own heavy aluminum box. It's been a 
thought for a while, and should address the thermal integration and 
time constants you referred to. For this system, it's doubtful that an 
underground bomb proof bunker is needed. ;) 
 I'd like to learn more about what testing could be done and would be 
more than happy to discuss this off line, if anyone is interested. 
 This thread has probably out lived it's useful life. 
  

 Thanks,
 Dan
  
  
  
 > LOL. A couple of seconds of warm air at 15C above ambient is a HUGE
 > temperature transient for any sensitive electronics, especially
 > anything with an oscillator. I would venture a guess that the lion's
 > share of the drift you see is the GPS time base shooting
 > off-frequency, but there are probably other effects, too (voltage
 > regulators, to name just one). 
 >

 > To me, a "little change" in this context might be blowing one warm
 > breath toward the GPS unit from 18" away and seeing what happens over
 > the next minute or two. 
 >

 > But the GPS temperature sensitivity shouldn't be a big factor in
 > actual use. The GPS should be thermally isolated from anything that
 > changes temperature rapidly, and enclosed such that external
 > temperature changes are integrated over at least tens of
 > minutes. Then, the inside of the enclosure will reach its own
 > thermal equilibrium and any external changes will be slowed enough to
 > be tracked out by the GPS discipline. My recommendation would be to
 > put it in a cast aluminum box (search the archives for "cast aluminum
 > box"), but there are others who think you need to build a two foot
 > cube out of cinderblocks and fire brick against a wall in the deepest
 > external corner of your basement. 
 >

 > OR, if my suspicion is correct that the temperature sensitivity is
 > mostly the GPS time base, figure out a way to kludge the GPS to
 > accept the disciplined OCXO as its time base. 
 >

 > Best regards,
 >
 > Charles

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Re: [time-nuts] Meaning of "SS" on status screen from 58503A

Hi

http://www.cnssys.com/files/M12+UsersGuide.pdf

On page 46 there is a pretty good chart for signal strength to c/n. The chart 
for the Motoroal GPS module in yours should be quite similar.

If there is no SCPI then it’s a “feature enhancement” in a later version of the 
firmware.

Are you looking at the data with a terminal program or via Z38xx? If it’s 
through Z38xx the program is probably converting things for you. >From the 
screen shot it looks like your are running a terminal. 

Sending:

*CLS

will clear the error message at the top of your screen ...

Bob

> On Dec 14, 2014, at 2:57 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 14 December 2014 at 19:52, Bob Camp  wrote:
>> Hi
>> 
>> SS is signal strength. There is a setting somewhere buried deep in the SCPI 
>> to switch the display units.
>> 
>> Bob
> 
> I guessed SS probably was signal strength, but what values are good
> and bad? There's nothing in any manual I can find that mentions SS on
> the 58503A. I can't find any SCPI command that is supposed to switch
> the display units.
> 
> Dave
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Dave Daniel


Well, thanks, everyone, for the information. I appreciate the help.

First, I am presently not up to adding another project to my long list 
of projects. I get whiplash every time I walk into the lab. Building a 
GPSDO sound like fun. Perhaps down the line.


I figured I should add some information about myself: I am an electrical 
engineer (currently employed) with a lot of digital/Verilog experience 
and a fair bit of analog experience (but less than my digital 
experience) and quite a bit of software experience, all of this from 
working for about thirty-eight years on various embedded systems. 
Currently, I shy away from writing code just because I don't enjoy it 
much and have done too much professionally. But I know that eventually I 
will need to write code in my lab. Presently, I am in the process of 
restoring some older ham radio gear, but I became sidetracked from that 
by the necessity to repair a bunch of vintage test equipment which 
effort has somehow taken on a life of it's own.


What I need right now is a frequency standard that is accurate enough to 
use as a reference for things like calibrating test gear. I also want to 
"play" with one before I build one. Just going through all of the 
educational material is a daunting task. I figured I'd combine an 
interest with GPSDOs in general with a need for an accurate enough 
"standard" (I use the term loosely here) to get some instruments 
calibrated.


Thanks again for all the information!

Cheers,
DaveD

I had forgotten about the LTE-lite; I should add that to the list of 
choices. I'm tending towards either a 10 MHz version of that or the 
Lucent boxes.

On 12/14/2014 8:00 AM, Bob Camp wrote:

Hi


On Dec 14, 2014, at 12:47 AM, Chris Albertson  wrote:

I tried to see just how simple, low cost and self contained I could make a
GPSDO.  I started with the Lars Walenius design then removed everything I
could from it.  I replace all the software with just a small loop with
about a dozen lines of code so it would be easy to understand.

My goal was to make something that could be built and tested using just
basic equipment.  The question is of course "How do you know the unit is
making a 10 MHz signal if you don't already have a 10MHz reference to
compare it to?"  Well you can assume that your 1PPS reference is accurate.

Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably 
accurate over very long time spans. Over short spans the pps moves around a lot.


Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles
per each PPS.

If you do a tight lock (“EXACTLY”)  against a GPS PPS that is moving +/- 10 ns, 
your frequency will swing +/- 1x10^-8 every second


Count both for a few days and verify the ratio remains at
ten million to one, exactly.

Ok, that’s looking at the long term where GPS is indeed accurate. That’s the 
easy part on any GPSDO design.


  I ran mine for about 8 weeks and it stays at
the desired ratio.I know this is not a perfect test because it could
have been running at zero hertz for 30 seconds and then 20MHz for 30
seconds but I assume the OCXO is better than that.   The point is that once
you have the GPS working you DO have a  pretty good 1Hz reference.

Well, not quite so fast. You just jumped over a massive amount of work that 
normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every 
second would pass your test. (which is not in any way to say that your design 
actually does that).  It would make a lousy GPSDO for most uses. You very much 
*do* need to check the ADEV (or what ever) close in and tune your filter up to 
match your parts.


Cost:
Motorola Oncore GPS$18
magnnetic patch antenna   6
OCXO (eBay)   19
Arduino, mini  3
PLL chip 2
TTL diver chip1
Plug-in power cube0
perf-board  1

Total cost of GPSDO $50

Just a side note - A *lot* of the $19 OCXO’s I have from eBay are in very poor 
shape spec wise. Testing them before using them would be a very good idea.

Bob



Actually I do have A Thunderbolt.  I place the 10MHz output of the above
unit and the TB on my dual channel scope and was able to see the phase of
the two 10MHz references was locked.  I saw the phase drift over about an
hour but then it would pull back.   But I made this very simple and it
could be better.

Actually I've added  some features to it like a 2 line by 16 character LCD
display and some status LEDs.  And I can log data to a computer via a USB
cable so it is easy to plot data and it is using my more expansive mast
mounted timing antenna.

The Arduino based design is OK for controlling an OCXO but I think it is
best used for controlling my Rubidium oscillator.  The RB is so stable I
should only update the frequency control every few hours at most.

On Sat, Dec 13, 2014 at 7:21 PM, Jim Harman  wrote:

On Sat, Dec 13, 2014 at 9:36 PM, Bob Camp  wrote:


The

Re: [time-nuts] Set time on Solaris computer from HP 58503A

2014-12-14 Thread Chris Albertson

I would still like to experiment with it. As I wrote earlier I bought this
> for a frequency reference,  not a clock, but I would not object to a bit of
> fun messing around with it.
>
>
If the goal is just getting good enough time onto the Solaris machine then
use NTP and some pool servers on the Internet.  You get about 10
millisecond level accuracy and the cost is zero.  If you have solaris
running you might even have this all setup and running.  If not do this as
the first step and verify it works.

If 10ms is unacceptable, next step is to connect the PPS signal.  Doing
this will move you from milli to micro second level accuracy.   It is easy
if the Solaris machine has a real serial port.   If you have to go through
a USB dongle you loose about an order of magnitude accuracy but this is
still very good.

There is zero point in buying a special computer to run NTP.  Just use any
computer you own that is already running 24x7.  Of course if you don't have
a computer that runs 24x7 then you would look for one that uses very little
power.

Don't worry to much if the USB connection skews the time on the NTP server
by some tens of microseconds, your server can't transfer time to your other
computers on the LAN any better than millisecond level so a few tenths of
an millisecond hardly mater.

My opinion of computer time is that for normal use being a few milliseconds
off is OK because the typical monitor is refreshed no faster than 100Hz so
you have lag cause by screen refresh times even if the internal clock is
dead-on perfect.  Same for disk time stamps, these is lag in the IO system
too


-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Chris Albertson

It's not worth making a PCB, not when you can buy the whole thing already
assembled for $3 with free shipping.  I use these just as if they where a
single chip and put them in a socket.  See eBay 141505833625 as an example.
  Those holes are in 0.1 inch centers so you can figure out the size. (I
get 1.3 inches long.)  direct link

I'll write up what I built.  It would be good to see the range of these.  I
tried to make mine as simple an low cost as possible without regard to
anything else.  Just to find the bottom line.  I doubt I would have met
that gaol by using a bare AVR chip.  That is NOT simple because it requires
so much more skill from the builder and with an entire working Arduino
selling for $3 how much could you save?  Actually the chips on that $3
board cost more than $3. (I don't even see how shipping from China can be
that cheap.)

On Sat, Dec 13, 2014 at 10:56 PM, Patrick Tudor  wrote:
>
>
> > On Dec 13, 2014, at 9:47 PM, Chris Albertson 
> wrote:
> >
> > Actually I've added  some features to it like a 2 line by 16 character
> LCD
> > display and some status LEDs.  And I can log data to a computer via a USB
> > cable so it is easy to plot data and it is using my more expansive mast
> > mounted timing antenna.
>
>
> Just in case any of you like reading Arduino code, for fun or functions to
> copy-and-paste,
> the code for my PCB that combines an ATMega328p with an Adafruit GPS and
> 16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at
> GitHub.
> It’s not exactly, say, measuring oscillator cycles (yet... ) but it’s
> perhaps
> a good introduction for someone who’s never ever before used anything
> Arduino.
> (And now that I’ve done more PCBs with Cypress and FTDI chips, I wish I’d
> put
> that straight on my board instead of as a future daughterboard, but,
> feature creep.)
>
> https://github.com/ptudor/jemma-clock
>
> PT
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-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

The desktop version (with handle) used the rubber “bumper” wrap around for 
feet. The bumpers got pulled when they were rack mounted. The ones that got put 
back on may or may not be identical to the originals. That’s a very normal part 
of the surplus process. The 100% correct HP original case on the box as HP 
built it did not use the clip on feet. 

The reason for this is pretty simple. The Z3801 / Z3805 came before the 
“instrument” versions of the same products. The internal case structure is 
same/ same. The instrument simply gets a gray sheet metal jacket that fits 
around the Z38xx box. That’s the way HP designed it. Since its just a jacket, 
it gets feet as part of the bumpers. Most of these (likely 99%) got rack 
mounted and the feet / bumpers were tossed. I have a *lot* of very legit 
surplus HP gear that did not come with feet or bumpers. 

Bob

> On Dec 14, 2014, at 2:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 14 December 2014 at 19:32, Bob Camp  wrote:
> 
>>> There are not the usual 3 holes underneath where feet go.
>> 
>> I understand that they are different. The problem is the same though. 
>> Pulling a box in and out of a rack with feet or bumpers on it is a pain. 
>> They often get “lost” early in the instrument’s life. Often it’s a standard 
>> process on all gear as it comes into the facility.  All of the un-needed 
>> bits and pieces go into a big pile. When the feet (or whatever) are found 
>> later in life they may or may not be re-installed correctly. They might not 
>> even be the ones that came with the instrument.
>> 
>> Bob
> 
> I am not sure if you are following me. On most (all??) HP kit I have
> seen, there are 3 holes at each corner of the bottom, where is
> possible to fit feet if one is going to use it on a desktop, rather
> than a rack. This unit does not have those holes, so it would be
> impossible to fit the usual HP feet on it.
> 
> Looking around, I have 15 bits of HP kit,  all of which have holes in
> the corner for feet. But this 58503A, with the Chinese box, does not
> have the holes. I don't know whether the 85053A is supposed to have
> them, or whether this is just a flaw in the design of the counterfeit.
> 
> Dave
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Alan Hochhalter

The 58503A in the picture on leapsecond.com looks very similar to my older
34401A DVM which doesn't have separate feet.  The molded plastic pieces on
both ends have those crenelations that serve the same function.

Alan

On Sun, Dec 14, 2014 at 12:46 PM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:
>
> On 14 December 2014 at 19:32, Bob Camp  wrote:
>
> >> There are not the usual 3 holes underneath where feet go.
> >
> > I understand that they are different. The problem is the same though.
> Pulling a box in and out of a rack with feet or bumpers on it is a pain.
> They often get “lost” early in the instrument’s life. Often it’s a standard
> process on all gear as it comes into the facility.  All of the un-needed
> bits and pieces go into a big pile. When the feet (or whatever) are found
> later in life they may or may not be re-installed correctly. They might not
> even be the ones that came with the instrument.
> >
> > Bob
>
> I am not sure if you are following me. On most (all??) HP kit I have
> seen, there are 3 holes at each corner of the bottom, where is
> possible to fit feet if one is going to use it on a desktop, rather
> than a rack. This unit does not have those holes, so it would be
> impossible to fit the usual HP feet on it.
>
> Looking around, I have 15 bits of HP kit,  all of which have holes in
> the corner for feet. But this 58503A, with the Chinese box, does not
> have the holes. I don't know whether the 85053A is supposed to have
> them, or whether this is just a flaw in the design of the counterfeit.
>
> Dave
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Re: [time-nuts] Beaglebone NTP server

2014-12-14 Thread folkert

> > On my rpi the jitter is between 2 and 10us iirc but it is a while since
> > I tested it. A quick peak shows me currently 3us jitter. Not bad for a
> > userspace solution imho.
> 
> 
> Really?   The PPS to GPIO interface is handles in user space?  It is not
> interrupt driven?

Yes it is. But, until today, I used a software solution which
interfaces the interrupt to ntp. I did that because I hate recompiling
kernels and the pps code for rpi+gpio was not in the main distrio.



Folkert van Heusden

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Re: [time-nuts] Meaning of "SS" on status screen from 58503A

On 14 December 2014 at 19:52, Bob Camp  wrote:
> Hi
>
> SS is signal strength. There is a setting somewhere buried deep in the SCPI 
> to switch the display units.
>
> Bob

I guessed SS probably was signal strength, but what values are good
and bad? There's nothing in any manual I can find that mentions SS on
the 58503A. I can't find any SCPI command that is supposed to switch
the display units.

Dave
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Re: [time-nuts] Meaning of "SS" on status screen from 58503A

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

SS is signal strength. There is a setting somewhere buried deep in the SCPI to 
switch the display units.

Bob

> On Dec 14, 2014, at 2:40 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> Hi,
> 
> I'm trying to make sense of the output from the status screen of this GPSDO
> 
> E-113> :SYSTEM:STATUS?
> --- Receiver Status 
> ---
> 
> SYNCHRONIZATION . [ Outputs Valid 
> ]
> SmartClock Mode ___   Reference Outputs 
> ___
>>> Locked to GPS  TFOM 3 FFOM 0
>   Recovery   1PPS TI +48.6 ns relative to GPS
>   Holdover   HOLD THR 1.000 us
>   Power-up   Holdover Uncertainty 
>  Predict  8.5 us/initial 24 hrs
> 
> ACQUISITION  [ GPS 1PPS Valid 
> ]
> Tracking: 6    Not Tracking: 1    Time 
> 
> PRN  El  Az   SS   PRN  El  AzUTC  19:12:37 14 Dec 
> 2014
>  5  43 191   7121  13 307GPS 1PPS Synchronized to UTC
> 13  67  96   59  ANT DLY  0 ns
> 15  36 290   52  Position 
> 26  81 307   50  MODE Hold
> 28  50 108   53
> 30  39  62   45  LAT  N  51:39:04.122
>  LON  E   0:46:36.379
> ELEV MASK 10 deg  HGT   +44.16 m  
> (MSL)
> HEALTH MONITOR . [ OK 
> ]
> Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
> E-113>
> 
> 
> What does the "SS" mean? According to the 58503A / 59551A *Symmetricom* manual
> 
> http://www.leapsecond.com/museum/hp59551a/097-59551-02-iss-1.pdf
> 
> there should be a "C/N" there, not a "SS". The manual says 50 is the
> maximum value for C/N, and 35 is the minimum for stable tracking. The
> fact I have four satellites showing an SS of over 50 indicates that I
> can't just assume SS=C/N.
> 
> The manual for the 58503B,
> 
> http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf
> 
> which I assume is a later model than the 58503A, says again C/N is
> used on the 58503B, but it does say "SS" is used on the 59551A, which
> is a quite a different beast - it does not have a 10 MHz output. For
> that it says SS ranges from 0 to 255, and that 20-30 is weak. *IF* I
> can assume the SS in the 58503A works the same was as SS in the
> 59551A, then it looks like I have 6 satellites which are not weak. But
> that is a big "IF"
> 
> Does anyone have an HP manual for the 58503A?
> 
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, 
> UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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Re: [time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

2014-12-14 Thread Gerhard Hoffmann


Am 14.12.2014 um 18:46 schrieb Arthur Dent:

Before you pooh-pooh these transformer/filters, try feeding a 10Mhz square
wave into a one of these filters and check out the fairly clean sine wave
you get out. These are handy cheap units and I have used them in the past
as a quick and not so dirty way to clean up a 10Mhz signal.


From a time nut pov this is probably less cleaning and more like infecting
with phase errors that drift along at the mercy of the temp. behaviour of
some unknown piece of ferrite.

regards, Gerhard

(who is just winding the Amidon cores for the 5 and 15 MHz traps of his
5->10MHz doubler for the new Lucent.  1812 chokes have failed big time.)
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

On 14 December 2014 at 19:32, Bob Camp  wrote:

>> There are not the usual 3 holes underneath where feet go.
>
> I understand that they are different. The problem is the same though. Pulling 
> a box in and out of a rack with feet or bumpers on it is a pain. They often 
> get “lost” early in the instrument’s life. Often it’s a standard process on 
> all gear as it comes into the facility.  All of the un-needed bits and pieces 
> go into a big pile. When the feet (or whatever) are found later in life they 
> may or may not be re-installed correctly. They might not even be the ones 
> that came with the instrument.
>
> Bob

I am not sure if you are following me. On most (all??) HP kit I have
seen, there are 3 holes at each corner of the bottom, where is
possible to fit feet if one is going to use it on a desktop, rather
than a rack. This unit does not have those holes, so it would be
impossible to fit the usual HP feet on it.

Looking around, I have 15 bits of HP kit,  all of which have holes in
the corner for feet. But this 58503A, with the Chinese box, does not
have the holes. I don't know whether the 85053A is supposed to have
them, or whether this is just a flaw in the design of the counterfeit.

Dave
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[time-nuts] Meaning of "SS" on status screen from 58503A

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi,

I'm trying to make sense of the output from the status screen of this GPSDO

E-113> :SYSTEM:STATUS?
--- Receiver Status ---

SYNCHRONIZATION . [ Outputs Valid ]
SmartClock Mode ___   Reference Outputs ___
>> Locked to GPS  TFOM 3 FFOM 0
   Recovery   1PPS TI +48.6 ns relative to GPS
   Holdover   HOLD THR 1.000 us
   Power-up   Holdover Uncertainty 
  Predict  8.5 us/initial 24 hrs

ACQUISITION  [ GPS 1PPS Valid ]
Tracking: 6    Not Tracking: 1    Time 
PRN  El  Az   SS   PRN  El  AzUTC  19:12:37 14 Dec 2014
  5  43 191   7121  13 307GPS 1PPS Synchronized to UTC
 13  67  96   59  ANT DLY  0 ns
 15  36 290   52  Position 
 26  81 307   50  MODE Hold
 28  50 108   53
 30  39  62   45  LAT  N  51:39:04.122
  LON  E   0:46:36.379
ELEV MASK 10 deg  HGT   +44.16 m  (MSL)
HEALTH MONITOR . [ OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv: OK
E-113>


What does the "SS" mean? According to the 58503A / 59551A *Symmetricom* manual

http://www.leapsecond.com/museum/hp59551a/097-59551-02-iss-1.pdf

there should be a "C/N" there, not a "SS". The manual says 50 is the
maximum value for C/N, and 35 is the minimum for stable tracking. The
fact I have four satellites showing an SS of over 50 indicates that I
can't just assume SS=C/N.

The manual for the 58503B,

http://www.leapsecond.com/museum/hp58503a/097-58503-13-iss-1.pdf

which I assume is a later model than the 58503A, says again C/N is
used on the 58503B, but it does say "SS" is used on the 59551A, which
is a quite a different beast - it does not have a 10 MHz output. For
that it says SS ranges from 0 to 255, and that 20-30 is weak. *IF* I
can assume the SS in the 58503A works the same was as SS in the
59551A, then it looks like I have 6 satellites which are not weak. But
that is a big "IF"

Does anyone have an HP manual for the 58503A?

Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT, UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

Hi

> On Dec 14, 2014, at 2:14 PM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 14 December 2014 at 02:31, Bob Camp  wrote:
>> Hi
>> 
>> You see a lot of surplus HP gear with the feet pulled. That was pretty 
>> standard when gear was rack mounted.
>> 
>> Bob
> 
> There are not the usual 3 holes underneath where feet go.

I understand that they are different. The problem is the same though. Pulling a 
box in and out of a rack with feet or bumpers on it is a pain. They often get 
“lost” early in the instrument’s life. Often it’s a standard process on all 
gear as it comes into the facility.  All of the un-needed bits and pieces go 
into a big pile. When the feet (or whatever) are found later in life they may 
or may not be re-installed correctly. They might not even be the ones that came 
with the instrument. 

Bob

> 
> I would nice to be able to find a few photos of a real 58503A. Does
> anyone have a known genuine one?
> 
> I suspect this will go back to China, so I'm not going to spend much
> time on it, but I have slid the the case back 25  mm or so, to get a
> bit more ventilation. The electronics runs much cooler. I would not
> want it to overheat before it gets back to China.
> 
> Dave
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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

They are pretty fancy little gizmos if you want to do twisted pair. Volume 
counts here in terms of making them cheap. 

Twisted pair is *good* stuff for isolation at low frequencies. It’s not so hot 
for microwaves. There is an item called STP (shielded twisted pair) that 
addresses the microwave part pretty well. 

Will it beat some $1K / foot quartz filled uber coax for delay dispersion .. of 
course not. If you have those sort of needs (and credit card) go for the fancy 
coax. Plugging twisted pair into the back of a HP 5334 is a bit awkward as 
well. If you are running < 6 feet from distribution point to instrument, don’t 
bother with any of this stuff. Same goes if everything is already very solidly 
bonded to a common ground. Yes if you are in the middle of a DMTD or a phase 
noise tester other rules may apply. 

Have a GPSDO buried in a 100’ deep dry hole in the back yard, 400’ from your 
house, running on it’s own isolated nuclear generator? These are pretty good 
gizmos to think about.

Bob


> On Dec 14, 2014, at 1:41 PM, paul swed  wrote:
> 
> Well with zero effort the spec sheet. Bob indeed there are common mode
> chokes in them. Jeeze a lot in 1 package along with center taps.
> Regards
> Paul
> WB8TSL
> 
> On Sun, Dec 14, 2014 at 12:22 PM, Bob Camp  wrote:
>> 
>> Hi
>> 
>> If you get the whole magnetics package (and not just a transformer) it
>> probably will have a pretty good common mode choke in it. If you go back to
>> the days of coax ethernet, the choke was more the “magic” that let them go
>> to twisted pair than the transformer.
>> 
>> Why does this matter?
>> 
>> Well … we seem to still be stuck back in the “coax ethernet” era when it
>> comes to standard distribution. Every time somebody brings up a need to go
>> hundreds of feet, coax becomes a second choice sort of solution. That’s
>> even more true for a pps. Don’t toss out the rest of the magnetics when you
>> salvage one of these old beasts …
>> 
>> Why mention pps? There are more than one isolated pair on those
>> connectors. You would need to modulate the pps onto something at one end
>> and demodulate it at the other end. There are a lot of cheap ways to do
>> that, very much so if you are generating the pps yourself in something on
>> the transmitting end.
>> 
>> Bob
>> 
>> 
>>> On Dec 14, 2014, at 11:59 AM, Alan Melia 
>> wrote:
>>> 
>>> Hi Paul I confirm the 17MHz LPF response I didn't measure them for
>> flatness :-)) The source I used was surplus 16way 10BaseT switches which
>> were junked some time back but may still be lying in the back of store-room
>> cupboards.you get a lot on one board that way.
>>> 
>>> Alan
>>> G3NYK
>>> 
>>> - Original Message - From: "paul swed" 
>>> To: "Time-nuts" 
>>> Sent: Sunday, December 14, 2014 4:18 PM
>>> Subject: [time-nuts] Frequency distribution isolation transformers
>> YCL20F001n arrived
>>> 
>>> 
 Another Time-nut suggested the use of 10 baseT ethernet transformers
>> for 10
 MHz isolation that he pulls from old ethernet boards. The 20F001n. These
 are available from UTSource on ebay at 90 cents each NOS. Ordered 20.
 
 Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT
 then how could they be when they are a pretty flat transformer from 40
>> KHz
 to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some
>> lumps
 and bumps in that pass band But not large maybe 1-1.3db I need to get
>> much
 more accurate. But now I have a nice transformer that can work at WWVB
>> 60
 Khz as well as with frequency distribution.
 They come in a dip foot print and 2 X to a package.
 I have more to check because to good to be true almost always is. At
>> least
 for me.
 Regards
 Paul
 WB8TSL
 ___
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 To unsubscribe, go to
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 and follow the instructions there.
>>> 
>>> ___
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>> 
> <20F001N.pdf>___
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

On 14 December 2014 at 02:31, Bob Camp  wrote:
> Hi
>
> You see a lot of surplus HP gear with the feet pulled. That was pretty 
> standard when gear was rack mounted.
>
> Bob

There are not the usual 3 holes underneath where feet go.

I would nice to be able to find a few photos of a real 58503A. Does
anyone have a known genuine one?

I suspect this will go back to China, so I'm not going to spend much
time on it, but I have slid the the case back 25  mm or so, to get a
bit more ventilation. The electronics runs much cooler. I would not
want it to overheat before it gets back to China.

Dave
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Re: [time-nuts] Ventilation of HP 58503A GPS time & frequency reference receiver

2014-12-14 Thread Scott McGrath

>From pictures bumpers are installed in an inverted position.  Reverse them

Whoever put this together in CN did not have any idea of how this series of 
cases are assembled or did not care

Content by Scott
Typos by Siri

> On Dec 13, 2014, at 2:08 PM, HP-mini  wrote:
> 
> On Sat, 2014-12-13 at 15:18 +, Dr. David Kirkby (Kirkby Microwave
> Ltd) wrote:
> 
>> I just noticed. Since there are no feet on this, there is no way any
>> air can get into the slots in the base The oven was running too
>> hot for me to touch - I doubt that is normal, but perhaps others no
>> different.
>> 
>> Dave
> 
> Pull the rear rubberized plastic bump stop off the case & fit it up the
> other way.
> 
> As long as the OCXO operates below its turning point it has thermal
> control. Only need to dissipate the non-heating power, that sets the max
> operating temperature.
> Some OCXOs are quieter running in high temperature ambient still air.
> All are degraded by changes in thermal load.
> Brett.
> 
> 
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Re: [time-nuts] KS-24361 quirk

2014-12-14 Thread Paul

On Sat, Dec 13, 2014 at 11:55 PM, Hal Murray 
wrote:

> Can somebody confirm that the PPS and 15 MHz on the standby unit are
> disabled?
>

Yes, the PPS is held active.
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[time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

2014-12-14 Thread Arthur Dent

paulswedb at gmail.com
"Another Time-nut suggested the use of 10 baseT ethernet transformers for 10
MHz isolation that he pulls from old ethernet boards. The 20F001n. These
are available from UTSource on ebay at 90 cents each NOS. Ordered 20.

Well I have to say as a BPF or something for 10 Mhz they are
lousy.. "


Before you pooh-pooh these transformer/filters, try feeding a 10Mhz square
wave into a one of these filters and check out the fairly clean sine wave
you get out. These are handy cheap units and I have used them in the past
as a quick and not so dirty way to clean up a 10Mhz signal.

Several companies made these and they are all basically the same unit.
http://elcodis.com/parts/900719/FL1012.html#datasheet
http://akizukidenshi.com/download/ds/ycl/20F001NG.pdf

-Arthur
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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

Well with zero effort the spec sheet. Bob indeed there are common mode
chokes in them. Jeeze a lot in 1 package along with center taps.
Regards
Paul
WB8TSL

On Sun, Dec 14, 2014 at 12:22 PM, Bob Camp  wrote:
>
> Hi
>
> If you get the whole magnetics package (and not just a transformer) it
> probably will have a pretty good common mode choke in it. If you go back to
> the days of coax ethernet, the choke was more the “magic” that let them go
> to twisted pair than the transformer.
>
> Why does this matter?
>
> Well … we seem to still be stuck back in the “coax ethernet” era when it
> comes to standard distribution. Every time somebody brings up a need to go
> hundreds of feet, coax becomes a second choice sort of solution. That’s
> even more true for a pps. Don’t toss out the rest of the magnetics when you
> salvage one of these old beasts …
>
> Why mention pps? There are more than one isolated pair on those
> connectors. You would need to modulate the pps onto something at one end
> and demodulate it at the other end. There are a lot of cheap ways to do
> that, very much so if you are generating the pps yourself in something on
> the transmitting end.
>
> Bob
>
>
> > On Dec 14, 2014, at 11:59 AM, Alan Melia 
> wrote:
> >
> > Hi Paul I confirm the 17MHz LPF response I didn't measure them for
> flatness :-)) The source I used was surplus 16way 10BaseT switches which
> were junked some time back but may still be lying in the back of store-room
> cupboards.you get a lot on one board that way.
> >
> > Alan
> > G3NYK
> >
> > - Original Message - From: "paul swed" 
> > To: "Time-nuts" 
> > Sent: Sunday, December 14, 2014 4:18 PM
> > Subject: [time-nuts] Frequency distribution isolation transformers
> YCL20F001n arrived
> >
> >
> >> Another Time-nut suggested the use of 10 baseT ethernet transformers
> for 10
> >> MHz isolation that he pulls from old ethernet boards. The 20F001n. These
> >> are available from UTSource on ebay at 90 cents each NOS. Ordered 20.
> >>
> >> Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT
> >> then how could they be when they are a pretty flat transformer from 40
> KHz
> >> to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some
> lumps
> >> and bumps in that pass band But not large maybe 1-1.3db I need to get
> much
> >> more accurate. But now I have a nice transformer that can work at WWVB
> 60
> >> Khz as well as with frequency distribution.
> >> They come in a dip foot print and 2 X to a package.
> >> I have more to check because to good to be true almost always is. At
> least
> >> for me.
> >> 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.
> >
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20F001N.pdf
Description: Adobe PDF document
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Re: [time-nuts] Homebrew frequency counter, need help


Tom,

On 12/12/2014 08:01 PM, Tom Van Baak wrote:

Hi Li,

What you're doing is the same "trick" the Pendulum CNT-91 uses, as well as 
modern Agilent frequency counters, and even my own picPET.

The good news is that for frequency measurement all those many samples and the sqrt(N) 
advantage allow you to measure the frequency far more accurately than with traditional 
methods. That's why a hp 53132A can rightly advertise "12 digits/second".

The bad news is that what you gain in frequency resolution you lose in temporal 
resolution. This is why in spite of having 1 ps/s frequency specs, the counter 
has 150 ps single-shot time resolution. What most time interval counters then 
do is average in order to gain precision. This works fine unless what you're 
trying to measure is not time, or even frequency, but frequency stability 
(modulation domain). In that case averaging may remove the very thing you are 
trying to measure.

As for ADEV, all you need is the raw phase data, even at 9000 points per second 
(USB is fast enough), and let TimeLab take care of the rest. It will properly 
scale, decimate, and filter the data to produce correct ADEV plots, from your 
minimum tau0 of 0.000111 s out any tau you want. You will quickly see the noise 
floor of the counter this way.

Some papers to read:

Continuous time stamping
http://www.spectracomcorp.com/Desktopmodules/Bring2Mind/DMX/Download.aspx?EntryId=450


This is a good overview. Staffan got some minor factoids wrong, but who 
cares? It brings out the basic idea of history.


That ses of links is a good read. The HP Application note 200 series is 
also a good read for counters in general.


Do notice Staffan's heads-up that you need to measure on stable signals, 
as severer frequency drift will cause values to be, well a bit 
interesting. The reason is that the linear regression used is for a 
linear model and not quadratic model. Jim Barnes did an interesting 
analysis, and it turns out that regression measurements can be a bad 
solution for drift analysis.


The lesson that Staffan and Jim gives us is that just trying to apply 
your favorit magic without understanding side-consequences of systematic 
effects, may not give the effects you think.


Cheers,
Magnus
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Re: [time-nuts] tyco electronics A1025

2014-12-14 Thread Francesco Messineo

On Sun, Dec 14, 2014 at 6:12 PM, Bob Camp  wrote:

>>>
>>> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of 
>>> it. Finding one that will do position hold is even less likely. You can get 
>>> modules that will do both for < $20 and have a documented interface.
>>
>> that's not meant as a "time nut" stratum 1.
>> It's just a free gps module I would like to recycle as a needed
>> stratum 1 server for a small network.
>> Of course if I can find informations on it.
>> I know there're better options, but in this case anything would do.
>
> … and NTP is not a GPSDO or a Cs replacement.
>
> My guess is that there is no PPS out of the device. It would be very unusual 
> if there was. Finding the NEMA output pin should be possible with an 
> oscilloscope. At that point, a simple serial connection to the server is 
> about all you need. Bring up the NEMA driver and it is running. It is 
> unlikely that any further optimization would be possible, even with the 
> (maybe) 290 page data sheet on the part. I would not let the lack of a data 
> sheet stop you in this case. Hook up the output to a PC with a terminal 
> program and see what you get. The main problem would be if you need to find 
> the serial input pin to change what it puts out, hopefully you do not.



The A1029, which is a newer model, has indeed a PPS output and I've
been able to find a datasheet for it but the pinout isn't anything
like the A1025.
I planned to reverse engineer the pinout, but I'd like at least not to
be forced to try to guess the power pins. Maybe someone still has the
data for this older module.

Frank
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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

Hi

If you get the whole magnetics package (and not just a transformer) it probably 
will have a pretty good common mode choke in it. If you go back to the days of 
coax ethernet, the choke was more the “magic” that let them go to twisted pair 
than the transformer. 

Why does this matter? 

Well … we seem to still be stuck back in the “coax ethernet” era when it comes 
to standard distribution. Every time somebody brings up a need to go hundreds 
of feet, coax becomes a second choice sort of solution. That’s even more true 
for a pps. Don’t toss out the rest of the magnetics when you salvage one of 
these old beasts …

Why mention pps? There are more than one isolated pair on those connectors. You 
would need to modulate the pps onto something at one end and demodulate it at 
the other end. There are a lot of cheap ways to do that, very much so if you 
are generating the pps yourself in something on the transmitting end. 

Bob

> On Dec 14, 2014, at 11:59 AM, Alan Melia  wrote:
> 
> Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness 
> :-)) The source I used was surplus 16way 10BaseT switches which were junked 
> some time back but may still be lying in the back of store-room 
> cupboards.you get a lot on one board that way.
> 
> Alan
> G3NYK
> 
> - Original Message - From: "paul swed" 
> To: "Time-nuts" 
> Sent: Sunday, December 14, 2014 4:18 PM
> Subject: [time-nuts] Frequency distribution isolation transformers YCL20F001n 
> arrived
> 
> 
>> Another Time-nut suggested the use of 10 baseT ethernet transformers for 10
>> MHz isolation that he pulls from old ethernet boards. The 20F001n. These
>> are available from UTSource on ebay at 90 cents each NOS. Ordered 20.
>> 
>> Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT
>> then how could they be when they are a pretty flat transformer from 40 KHz
>> to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps
>> and bumps in that pass band But not large maybe 1-1.3db I need to get much
>> more accurate. But now I have a nice transformer that can work at WWVB 60
>> Khz as well as with frequency distribution.
>> They come in a dip foot print and 2 X to a package.
>> I have more to check because to good to be true almost always is. At least
>> for me.
>> Regards
>> Paul
>> WB8TSL
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Re: [time-nuts] tyco electronics A1025

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

Hi

> On Dec 14, 2014, at 12:01 PM, Francesco Messineo 
>  wrote:
> 
> On Sun, Dec 14, 2014 at 3:46 PM, Bob Camp  wrote:
>> 
>> Hi
>> 
>>> On Dec 14, 2014, at 6:03 AM, Francesco Messineo 
>>>  wrote:
>>> 
>>> Hi all,
>>> I've just found an old anti-theft system (I think) for cars . It has a tyco
>>> electronics A1205 gps module.
>>> I've been unable to find any information about this module, other than it
>>> should be a 3.3V 12 channel GPS module with serial NMEA output.
>>> Does anyone have any informations about it? Even a pinout would help. I'd
>>> like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
>>> Thanks in advance.
>> 
>> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of 
>> it. Finding one that will do position hold is even less likely. You can get 
>> modules that will do both for < $20 and have a documented interface.
> 
> that's not meant as a "time nut" stratum 1.
> It's just a free gps module I would like to recycle as a needed
> stratum 1 server for a small network.
> Of course if I can find informations on it.
> I know there're better options, but in this case anything would do.

… and NTP is not a GPSDO or a Cs replacement. 

My guess is that there is no PPS out of the device. It would be very unusual if 
there was. Finding the NEMA output pin should be possible with an oscilloscope. 
At that point, a simple serial connection to the server is about all you need. 
Bring up the NEMA driver and it is running. It is unlikely that any further 
optimization would be possible, even with the (maybe) 290 page data sheet on 
the part. I would not let the lack of a data sheet stop you in this case. Hook 
up the output to a PC with a terminal program and see what you get. The main 
problem would be if you need to find the serial input pin to change what it 
puts out, hopefully you do not. 

Bob

> 
> 
> Frank
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Re: [time-nuts] Frequency distribution isolation transformers YCL20F001n arrived

2014-12-14 Thread Alan Melia

Hi Paul I confirm the 17MHz LPF response I didn't measure them for flatness 
:-)) The source I used was surplus 16way 10BaseT switches which were junked 
some time back but may still be lying in the back of store-room 
cupboards.you get a lot on one board that way.


Alan
G3NYK

- Original Message - 
From: "paul swed" 

To: "Time-nuts" 
Sent: Sunday, December 14, 2014 4:18 PM
Subject: [time-nuts] Frequency distribution isolation transformers 
YCL20F001n arrived



Another Time-nut suggested the use of 10 baseT ethernet transformers for 
10

MHz isolation that he pulls from old ethernet boards. The 20F001n. These
are available from UTSource on ebay at 90 cents each NOS. Ordered 20.

Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT
then how could they be when they are a pretty flat transformer from 40 KHz
to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some 
lumps

and bumps in that pass band But not large maybe 1-1.3db I need to get much
more accurate. But now I have a nice transformer that can work at WWVB 60
Khz as well as with frequency distribution.
They come in a dip foot print and 2 X to a package.
I have more to check because to good to be true almost always is. At least
for me.
Regards
Paul
WB8TSL
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Re: [time-nuts] tyco electronics A1025

2014-12-14 Thread Francesco Messineo

On Sun, Dec 14, 2014 at 3:46 PM, Bob Camp  wrote:
>
> Hi
>
> > On Dec 14, 2014, at 6:03 AM, Francesco Messineo 
> >  wrote:
> >
> > Hi all,
> > I've just found an old anti-theft system (I think) for cars . It has a tyco
> > electronics A1205 gps module.
> > I've been unable to find any information about this module, other than it
> > should be a 3.3V 12 channel GPS module with serial NMEA output.
> > Does anyone have any informations about it? Even a pinout would help. I'd
> > like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
> > Thanks in advance.
>
> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of 
> it. Finding one that will do position hold is even less likely. You can get 
> modules that will do both for < $20 and have a documented interface.

that's not meant as a "time nut" stratum 1.
It's just a free gps module I would like to recycle as a needed
stratum 1 server for a small network.
Of course if I can find informations on it.
I know there're better options, but in this case anything would do.

Frank
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

On 14 Dec 2014 15:45, "Bob Camp"  wrote:
>

>
> There are some long and detailed threads back in the archives about just
how USB works and what this does to timing.
>
> Simple / quick summary:
>

The impact on pps timing could (and often is) quite major.

I would still like to experiment with it. As I wrote earlier I bought this
for a frequency reference,  not a clock, but I would not object to a bit of
fun messing around with it.

> Another alternative (and thus it’s popularity on the list) is to set up
something small and light weight as a dedicated NTP server on your local
LAN. That gets the timing issues of your local connection to the internet
out of the NTP equation. You can  get down under 10 us with a setup like
that. The result may be better than your ability to time an edge on the SUN
box, due to all the other overheads involved there. It’s also a nice stand
alone project that is far less likely to mess up your main machine. The
boards commonly used are < $100 and some are much cheaper than that.
>
> Bob

I can't really justify that given an accurate clock is not really necessary
for me.

Dave
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Re: [time-nuts] Homebrew frequency counter, need help

Hi

> On Dec 14, 2014, at 11:36 AM, Magnus Danielson  
> wrote:
> 
> 
> 
> On 12/12/2014 06:15 PM, Bob Camp wrote:
>> Hi
>> 
>>> On Dec 12, 2014, at 11:44 AM, Li Ang  wrote:
>>> 
>>> Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
>>> ref=5650 case.
>> 
>> In the “both same (5650 / 5650) case” your linear regression filtering is 
>> faking you out a bit. The SR620 counter has exactly this same issue. That’s 
>> probably for the same reason. It’s a fine test to see if you have various 
>> problems under control. It’s not a perfect way to estimate the number of 
>> digits you will get on a real measurement. Using two independent sources is 
>> a better way to do that.
>> 
>> When you have two identical signals, the TDC noise is the main issue. All 
>> the edges are arriving in the same relation to each other (same timing). The 
>> linear regression is (obviously) good at suppressing the sort of noise the 
>> TDC has. With two independent signals the noise is more complex. The edges 
>> arrive at various times relative to each other. More things contribute to 
>> the total noise. The linear regression is having a harder time suppressing 
>> that sort of noise. In some cases (as you observed) the linear regression is 
>> actually making things worse.
>> 
>> If Magnus was here, he would be tossing empty beer bottles at me and saying 
>> — see Bob, sqrt(N) doesn’t always work ….
> 
> Indeed, except I would not be tossing empty beer bottles at you, I might 
> jokingly attempt do, but never actually throw it. One has to realize that the 
> quantization noise of the TIC may seem to process as if it where white phase 
> noise, but it isn't random noise, it is a systematic noise and if you fool 
> around with the systematics is may work for you or against you.
> 
> I do consider to pass another bottle of good beer to Bob for good behavior. :)

…. as long as we don’t start tossing kegs at each other, I consider myself 
lucky :)

> 
>> The filtering process used does need to be adapted to the noise of the total 
>> system.
> 
> It's one of the forgotten parameters, and I've even seen good Sam Stein stand 
> up and say "we used to do this wrong" on the same point, you need to publish 
> and consider the bandwidth of your processing, as it *will* affect the ADEV 
> plot (but only MDEV and TDEV somewhat).
> 
>>> 
>>> Since I really want to reduce the noise, what is the best test set you
>>> suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2
>>> OCXO,
>> 
>> If the MV89’s are in good working condition, they are the best thing to 
>> compare.The have the best ADEV of the group you have available I would check 
>> them for output level and stability before I trusted them. There are a lot 
>> of defective parts on the market. People get some, sort them and sell the 
>> bad ones. The bad ones just keep getting re-sold again and again … My guess 
>> is that they were good parts at one time and they got damaged when pulled 
>> off boards. If you use them, keep them on power at all times. Any OCXO will 
>> do better if you run it that way.
> 
> In order to test if systematics is messing badly with you, measure the ADEV 
> of the oscillator as it is steered (and stabilized) to a number of different 
> frequencies. For larger offsets to the counter reference, multiple beatings 
> occurs within the regression interval. You want that number to be an even 
> number of beats, or the beat count to be so large that the phase of the last 
> beat does not care. Linear regression helps out, as it weighs out the 
> outermost measures compared to the central one, making the beating at the 
> beginning and end not care as much.
> 
> These are *systematic* noise effects, and as you play around with systematics 
> and processing, you might have the systematics works for or against you, but 
> at the same time, the random noise you try to measure will suffer the 
> processing filtering, and you need to recall that. If you balance these 
> properly, you can make good and correct measurements, it's just that few do.
> 
> Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system noises 
> as they show up there should be estimated separately and removed from the 
> random noise estimates. They have *way* different behaviors.

… and this is where it gets complicated. I would toss in the Hadamard deviation 
into that mix as well. If I had to only use three, I would include it with 
modified ADEV (MDEV) and TDEV. All three are available in TimeLab with the 
click of a button. If you start getting lots of data (9,000 points per second) 
I would toss in a frequency domain (FFT) analysis as well. FFT on phase data is 
not (as far as I know) a feature of TimeLab.

To start with, on all of these measures, you are looking for bumps and spikes. 
They are telling you that something is wrong. If you flip over to the phase 
plot in TimeLab, spikes and abrupt steps in it also are telling you the same 
s

Re: [time-nuts] tyco electronics A1025

Hi

Maybe a bit more on a timing receiver:

GPS is (for some reason) better known for navigation than for timing. In 
navigation the receiver moves around a lot. In most timing applications, the 
receiver is stationary. When moving, the mathematical solution to the “where am 
I / what time is it” question has errors in both terms. Often consumer grade 
GPS’s “push” the error into the time side of the solution to make the location 
appear more accurate. There is a lot of debate over this actually making the 
location more accurate or simply being a result of sloppy code. 

In a timing situation, with the location fixed, you can eliminate the location 
variability from the math. This involves a survey (often an automatic feature) 
of the location. Once the survey is complete, the timing data out of the 
receiver improves significantly. With improvements in the survey, the data may 
improve even more. This mode of operation is of no use in a normal non-timing 
situation. It only shows up in devices with firmware written for timing. 

Like it or not, all GPS devices are made as cheaply as possible against a 
design specification. The PPS out of the GPS comes from a free running TCXO on 
the simple modules. Since the TCXO can be anywhere relative to the PPS, there 
is an error in the edge that is delivered. It’s commonly referred to as 
sawtooth error. On a timing receiver, this error can be measured by the 
firmware and reported to “higher authority”. 

—

Does all this matter in all applications? No, of course it does not. It may 
well be overkill. That’s well worth considering along with all the other issues.

—

Coming back to the original point:

You can get modules for < $20 with some or all of the features above. They may 
also have other nice attributes (documentation ….). I have no idea what the 
value of the A1205 is to you. It may well be free at this point. If it does 
have a cost, compare it to the other modules as you look at it.

Another consideration is that your A1205 may be in fine shape and a random 
device off of eBay may have spent part of it’s life under water. There is no 
one single answer, only a lot of things to consider. 

Bob

> On Dec 14, 2014, at 11:07 AM, paul swed  wrote:
> 
> Should have added. You get great documentation also and everything is well
> established and most likely will handle some 1024 week rollovers.
> The old stuff is quite annoying with respect to this.
> Regards
> Paul
> WB8TSL
> 
> On Sun, Dec 14, 2014 at 11:05 AM, paul swed  wrote:
>> 
>> Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid
>> cheap!
>> Regards
>> Paul
>> WB8TSL
>> 
>> On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp  wrote:
>>> 
>>> Hi
>>> 
 On Dec 14, 2014, at 6:03 AM, Francesco Messineo <
>>> francesco.messi...@gmail.com> wrote:

 Hi all,
 I've just found an old anti-theft system (I think) for cars . It has a
>>> tyco
 electronics A1205 gps module.
 I've been unable to find any information about this module, other than
>>> it
 should be a 3.3V 12 channel GPS module with serial NMEA output.
 Does anyone have any informations about it? Even a pinout would help.
>>> I'd
 like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
 Thanks in advance.
>>> 
>>> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out
>>> of it. Finding one that will do position hold is even less likely. You can
>>> get modules that will do both for < $20 and have a documented interface.
>>> 
>>> Bob
>>> 

 Frank IZ8DWF
 ___
 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.
>>> 
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>>> and follow the instructions there.
>>> 
>> 
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Re: [time-nuts] Homebrew frequency counter, need help




On 12/12/2014 06:15 PM, Bob Camp wrote:

Hi


On Dec 12, 2014, at 11:44 AM, Li Ang  wrote:

Yes, you are right. 5650_5650 is sig=ref case. prs10_5650 is sig=prs10 and
ref=5650 case.


In the “both same (5650 / 5650) case” your linear regression filtering is 
faking you out a bit. The SR620 counter has exactly this same issue. That’s 
probably for the same reason. It’s a fine test to see if you have various 
problems under control. It’s not a perfect way to estimate the number of digits 
you will get on a real measurement. Using two independent sources is a better 
way to do that.

When you have two identical signals, the TDC noise is the main issue. All the 
edges are arriving in the same relation to each other (same timing). The linear 
regression is (obviously) good at suppressing the sort of noise the TDC has. 
With two independent signals the noise is more complex. The edges arrive at 
various times relative to each other. More things contribute to the total 
noise. The linear regression is having a harder time suppressing that sort of 
noise. In some cases (as you observed) the linear regression is actually making 
things worse.

If Magnus was here, he would be tossing empty beer bottles at me and saying — 
see Bob, sqrt(N) doesn’t always work ….


Indeed, except I would not be tossing empty beer bottles at you, I might 
jokingly attempt do, but never actually throw it. One has to realize 
that the quantization noise of the TIC may seem to process as if it 
where white phase noise, but it isn't random noise, it is a systematic 
noise and if you fool around with the systematics is may work for you or 
against you.


I do consider to pass another bottle of good beer to Bob for good 
behavior. :)



The filtering process used does need to be adapted to the noise of the total 
system.


It's one of the forgotten parameters, and I've even seen good Sam Stein 
stand up and say "we used to do this wrong" on the same point, you need 
to publish and consider the bandwidth of your processing, as it *will* 
affect the ADEV plot (but only MDEV and TDEV somewhat).




Since I really want to reduce the noise, what is the best test set you
suggest? All the frequency source I have: FE5650 Rb , PRS10 Rb , MV89a*2
OCXO,


If the MV89’s are in good working condition, they are the best thing to 
compare.The have the best ADEV of the group you have available I would check 
them for output level and stability before I trusted them. There are a lot of 
defective parts on the market. People get some, sort them and sell the bad 
ones. The bad ones just keep getting re-sold again and again … My guess is that 
they were good parts at one time and they got damaged when pulled off boards. 
If you use them, keep them on power at all times. Any OCXO will do better if 
you run it that way.


In order to test if systematics is messing badly with you, measure the 
ADEV of the oscillator as it is steered (and stabilized) to a number of 
different frequencies. For larger offsets to the counter reference, 
multiple beatings occurs within the regression interval. You want that 
number to be an even number of beats, or the beat count to be so large 
that the phase of the last beat does not care. Linear regression helps 
out, as it weighs out the outermost measures compared to the central 
one, making the beating at the beginning and end not care as much.


These are *systematic* noise effects, and as you play around with 
systematics and processing, you might have the systematics works for or 
against you, but at the same time, the random noise you try to measure 
will suffer the processing filtering, and you need to recall that. If 
you balance these properly, you can make good and correct measurements, 
it's just that few do.


Oh, and only use ADEV, MDEV and TDEV to estimate random noises, system 
noises as they show up there should be estimated separately and removed 
from the random noise estimates. They have *way* different behaviors.


Cheers,
Magnus - considering what beer will be best to start the evening with
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[time-nuts] Frequency distribution isolation transformers YCL 20F001n arrived

Another Time-nut suggested the use of 10 baseT ethernet transformers for 10
MHz isolation that he pulls from old ethernet boards. The 20F001n. These
are available from UTSource on ebay at 90 cents each NOS. Ordered 20.

Well I have to say as a BPF or something for 10 Mhz they are lousy. BUT
then how could they be when they are a pretty flat transformer from 40 KHz
to 17 MHz! Take that Mini-Circuits. (Only in jest) Yes there are some lumps
and bumps in that pass band But not large maybe 1-1.3db I need to get much
more accurate. But now I have a nice transformer that can work at WWVB 60
Khz as well as with frequency distribution.
They come in a dip foot print and 2 X to a package.
I have more to check because to good to be true almost always is. At least
for me.
Regards
Paul
WB8TSL
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Re: [time-nuts] tyco electronics A1025

Should have added. You get great documentation also and everything is well
established and most likely will handle some 1024 week rollovers.
The old stuff is quite annoying with respect to this.
Regards
Paul
WB8TSL

On Sun, Dec 14, 2014 at 11:05 AM, paul swed  wrote:
>
> Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid
> cheap!
> Regards
> Paul
> WB8TSL
>
> On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp  wrote:
>>
>> Hi
>>
>> > On Dec 14, 2014, at 6:03 AM, Francesco Messineo <
>> francesco.messi...@gmail.com> wrote:
>> >
>> > Hi all,
>> > I've just found an old anti-theft system (I think) for cars . It has a
>> tyco
>> > electronics A1205 gps module.
>> > I've been unable to find any information about this module, other than
>> it
>> > should be a 3.3V 12 channel GPS module with serial NMEA output.
>> > Does anyone have any informations about it? Even a pinout would help.
>> I'd
>> > like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
>> > Thanks in advance.
>>
>> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out
>> of it. Finding one that will do position hold is even less likely. You can
>> get modules that will do both for < $20 and have a documented interface.
>>
>> Bob
>>
>> >
>> > Frank IZ8DWF
>> > ___
>> > 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.
>>
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>>
>
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Re: [time-nuts] Homebrew frequency counter, need help


Hi Li Ang,

On 12/12/2014 04:40 PM, Li Ang wrote:

Hi Bob,
 The job done by linear regression is to reduce the uncertainty. This
counter is designed to use continous timestamp method. My current design
can measure 9000 times/second. If I only use the 1st and last one to
calculate, it's the traditional recipocal + interploator method. This is
what you can see on the chart named "without linear regression". The
uncertainty of slope(the frequency ratio of ref and signal ) is contributed
by these 2 measurements. With linear regression of all 9000 data within one
second, the uncertainty will reduced to smaller one. (I really can't
remember the ratio. Something like sqrt(9000)).


Bob's comment about filtering is correct. The lack of uncertainty is 
partly systematic and partly white noise. As you filter it, as with 
linear regression, you will weight samples with a parabolic value, 
called the Omega filtering, and this will act as a low-pass filter. The 
low-pass filter will alter the white-noise shape of the ADEV, as the 
bandwidth have reduced. This is strictly predictable by the processing. 
The produced ADEV curve is shaped by the measuring device and 
processing, not by the DUT, so it's not showing the "real ADEV" of the 
DUT, but it would not be doing that anyway. One such filtering mechanism 
exists in MDEV, but it has established formulas for how noise-shapes 
behave with various degrees of filtering, so therefore it is accepted as 
a standard.


Regression filtering for frequency measures have already been done in 
the Pendulum counter range, but not for phase measurements.


It's not as much as "right" or "wrong" as how you present the numbers 
and interprent them.


Cheers,
Magnus




while(1) {
 double t3;  //fraction part of refcnt, measured by tdc_gp22
 double ref_curr;
 uint32_t sig_curr;
 static double ref_start;
 static uint32_t sig_start;
 uint32_t refcnt, sigcnt;
 const uint32_t gate_time = 1000; // 1000ms gate time

 if (i == 0) {
 init_regression(&rv);
 cpld_rst();
 timestamp(&refcnt, &sigcnt, &t3);
 ref_start = refcnt - t3;
 sig_start = sigcnt;
 i++;
 continue;
 }

 timestamp(&refcnt, &sigcnt, &t3);

 regression_enter_data(&rv, refcnt - t3 - ref_start, sigcnt - 
sig_start);
 if (msecond < gate_time) {
 i++;
 continue;
 } else  {
 t = regression_slope(&rv) ; // with linear regression
 printf("\r\nFreq=%.*f", 14, t);
 ref_curr = refcnt - t3;
 sig_curr = sigcnt;

 t = CalcFreq(ref_curr - ref_start, sig_curr -
sig_start); // without linear regression
 printf(" Interpolated=%.*f", 12, t);

 msecond = 0;
   i = 0;
 }
}

2014-12-12 21:18 GMT+08:00 Bob Camp :


HI


On Dec 12, 2014, at 4:04 AM, Tom Van Baak  wrote:

This large posting is from Li Ang.
/tvb

- Original Message -
From: Li Ang
To: Discussion of precise time and frequency measurement
Sent: Thursday, December 11, 2014 7:37 AM
Subject: Re: [time-nuts] Homebrew frequency counter, need help


Hi Bob,
   I've sent the PCB to the factory and I am waiting for the new board.

This time, it's a 4-layer borad and changed from CPLD to FPGA. This is the
first time of FPGA & 4-layer project. Hope everthing be OK.

Very nice looking. I hope it works !!!


   TPS79333 as the LDO for TDC. Better PSRR and noise spec than before

(XC6206). Analog and digital parts have their dedicated LDO.



   While I'm waiting the the new board. I did a test with PRS10 & FE5650

with current board. It's strange that the 20s adev of "without linear
regression" is better than "with linear regression”

Be careful pre-processing ADEV data. There are a variety of statistical
“traps” you can fall into. An overly simple explanation is that ADEV looks
at noise and that most pre-processing is a filter. Filters take out noise.
Finding one that only takes out the “bad noise” and keeps the “good noise”
can be quite difficult.

What exactly are you doing in your linear regression computation?

Bob




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Re: [time-nuts] tyco electronics A1025

Strongly agree with Bob. The neo 6 on ebay is a good example silly stupid
cheap!
Regards
Paul
WB8TSL

On Sun, Dec 14, 2014 at 9:46 AM, Bob Camp  wrote:
>
> Hi
>
> > On Dec 14, 2014, at 6:03 AM, Francesco Messineo <
> francesco.messi...@gmail.com> wrote:
> >
> > Hi all,
> > I've just found an old anti-theft system (I think) for cars . It has a
> tyco
> > electronics A1205 gps module.
> > I've been unable to find any information about this module, other than it
> > should be a 3.3V 12 channel GPS module with serial NMEA output.
> > Does anyone have any informations about it? Even a pinout would help. I'd
> > like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
> > Thanks in advance.
>
> It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of
> it. Finding one that will do position hold is even less likely. You can get
> modules that will do both for < $20 and have a documented interface.
>
> Bob
>
> >
> > Frank IZ8DWF
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Re: [time-nuts] raspberry pi, pps & interrupts by kernel

2014-12-14 Thread folkert

Hi,

> > I tested it...and could not get it to work. gpsd opens pps0 but strace
> > does not show me the regular ppsapi syscalls and also ppstest gives a
> > time out.
> 
> e.g. I did an strace and I did not see any PPS_FETCHs passing by.
> I verified with lsof that gpsd does have pps0 open.

With help from Hal I got it to work!
I thought you could just "poke" the gpio pin number in that /sys
virtual file. You can't. The bcm2708 code needs to know the pin number
at boot time.
Then, you can't get the pps via gpsd: when gpsd opens /dev/ttyAMA0 to
talk to the gps, a new /dev/pps1 is created, for that AMA0 device. That
pps1 is not the one you need; the serial port on the raspberry pi has no
dcd pin so pps1 points to nothing. Yes it is connected to the ldisc but
that has no (hardware) dcd pin connected to it.
So long story short: you need to configure an atom driver in ntpd which
then correctly opens /dev/pps0 and then the share memory coupling with
gpsd. Yeah or connect ntpd directly to /dev/ttyAMA0 but then you'll
miss the possibilities of running the nice gpsmon application.


Folkert van Heusden

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Re: [time-nuts] Set time on Solaris computer from HP 58503A

Hi

> On Dec 14, 2014, at 8:38 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
> On 14 December 2014 at 12:39, Neil Schroeder  wrote:
>> Based on my recent testing - including Solaris - you will be better off
>> with the Internet unless your USB adapter is far better behaved than the
>> several I have here
> 
> The USB -> serial adapter I have is an Keyspan USA-19HS
> 
> http://www.tripplite.com/high-speed-usb-to-serial-adapter-keyspan~USA19HS/
> 
> I bought that one, as it was officially supported by Sun. I also have
> another one somewhere - forget which model. Again that was officially
> supported by Sun.

There are some long and detailed threads back in the archives about just how 
USB works and what this does to timing. 

Simple / quick summary:

To do a proper / accurate time transfer, an edge from a source needs to be 
accurately clocked into the target machine. Any delay in this process is a bad 
thing. There are a lot of places delay can come from. 

USB is a packett / block transfer protocol. It gets it’s speed from sending a 
lot of stuff all at one time. When a serial USB sees a long string coming in, 
it formats it into a single block and transfers the whole thing in one bus 
transaction. That’s perfect for most things (commercial or consumer). The 
device gets on the bus and off the bus quickly with minimum overhead involved.

Waiting on something like a pps string is a real bad idea. Your serial port is 
running at a rational baud rate. At 9600 baud, each character time you delay 
messes up the PPS timing by almost a millisecond.  The PPS ID strings are many 
characters long. The impact on pps timing could (and often is) quite major. 
Even in the “best case” of sending the data one or two characters later, the 
pps is not very accurate. In the “worst case” it’s 10X or maybe 100X less 
accurate still. 

Some numbers:

1) PPS out of your GPSDO is likely < 100 ns all the time. Most of the time (one 
sigma) it’s in the 10 to 30 ns range depending on which box you are running. 

2) One character at 8N1 is 10 bits. At 9600 baud that’s 1.04 ms. It’s unlikely 
the USB sends in less than 1 character time.

3) A normal string is in the 30 to 40 characters range. A normal USB will 
buffer for 30X the character time ...

NTP via ethernet, with well chosen servers, can get you down to < 10 ms timing 
on you machines. It’s reliable and fairly easy to set up. The other alternative 
is to get the PPS edge into the machine in a more direct manner than USB. Yes I 
have a pile of SUN boxes, they often don’t come with all the i/o chards you 
might like to have….

Another alternative (and thus it’s popularity on the list) is to set up 
something small and light weight as a dedicated NTP server on your local LAN. 
That gets the timing issues of your local connection to the internet out of the 
NTP equation. You can  get down under 10 us with a setup like that. The result 
may be better than your ability to time an edge on the SUN box, due to all the 
other overheads involved there. It’s also a nice stand alone project that is 
far less likely to mess up your main machine. The boards commonly used are < 
$100 and some are much cheaper than that. 

Bob

> 
> Both have worked for industrial control applications, whereas I gather
> some cheap ones are only suitable for common consumer devices.
> 
> In any case, it will be more fun & educational to use the GPS
> receiver. To be honest, I don't need great accuracy. I only bought the
> unit as a frequency standard - the clock functionality is not
> important to me, but if I can have a bit of fun playing around with
> it, then I will.
> 
> Dave
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Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...


> On Dec 14, 2014, at 9:46 AM, Neil Schroeder  wrote:
> 
> The oscillator in he m8f is a vctcxo and can be steered with feedback or
> controlled by the host.
> 
> Also the m8f can send compliant DAC words to a TLV8515 and and MCP part via
> i2c for external
> VCXOs. It accepts their return signal on what would normally  be its
> feedback in ports.

The oscillator in the LEA-6T is not a VCTCXO and it’s got the same notes on it.

Bob

> 
> On Sunday, December 14, 2014, Bob Camp  wrote:
> 
>> Hi
>> 
>> There is also a little note down in the (many) notes section:
>> 
>> Not all features are available with all firmware versions.
>> 
>> It applies to all of the external inputs (like USB and SPI).
>> 
>> Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding
>> feature would not help in the case of biasing the unit with a hot air gun.
>> It would still loose lock as the TCXO went nuts.
>> 
>> The ideal outcome would be a system that reported against the external
>> input rather than the internal TCXO. Since they digitize the external pin
>> with the TCXO, the outcome is pretty coarse (10’s of ns). That’s not going
>> to help us much.
>> 
>> Bob
>> 
>>> On Dec 14, 2014, at 4:26 AM, Simon Marsh > > wrote:
>>> 
>>> 
>>> On 14/12/2014 04:08, d...@irtelemetrics.com  wrote:
> Note that most high-end GNSS timing receivers go one better and
>> simply have an external input for the clock. That way you feed your own lab
>> clock into the receiver. If you have Rb/Cs/maser you would use that as the
>> reference. It's what the national timing labs do, along with dual-frequency
>> and post-processing and all the other tricks of the trade.
>>> 
 I think it would be agreat idea also. It's a wonder that more of the
>> 'timing' receivers don't have that external clock option! I wonder what
>> these Ublox parts use for a clock? Is it something frequency compatible
>> with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) )
>>> 
>>> Ublox modules have a 48mhz internal clock.
>>> 
>>> There is the following interesting paragraph in at least the 7 & 8 data
>> sheets:
>>> 
>>> ---
>>> 
>>> 1.8.2 Aiding
>>> The EXTINT pin can be used to supply time or frequency aiding data to
>> the receiver.
>>> 
>>> For time aiding, hardware time synchronization can be achieved by
>> connecting an accurate time pulse to the EXTINT pin.
>>> 
>>> Frequency aiding can be implemented by connecting a periodic rectangular
>> signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high
>> phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide
>> the applied frequency value to the receiver using UBX messages.
>>> 
>>> ---
>>> 
>>> I haven't been able to find any information about what this actually
>> does though. Anyone know ?
>>> 
>>> Cheers
>>> 
>>> 
>>> Simon
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Re: [time-nuts] Fake 58503

Hi


> On Dec 14, 2014, at 9:53 AM, Magnus Danielson  
> wrote:
> 
> Fellow time-nuts,
> 
> I have seen the long debate about the fake 58503s. Maybe we should take a 
> step back and think a little about that. Why does someone rebuild say Z3801s 
> into 58503s?

or convert 3805’s the same way …

> Because somehow they are expected to have a higher value, and therefore there 
> is a profit to be made in doing so.
> 
> Why is there a higher value? Because the potential buys have made that 
> decision, sub-consciously. There is a few differences, but to some degree 
> they are superficial.
> 
> If you want to reduce the likelihood of being fooled by fakes, then don't 
> raise certain "magic number" boxes to the skies and prices with it.
> 
> I could make better use of my Z3801A if I did a few mods myself, beyond the 
> modification from RS422 to RS232. Honest mods and upgrades is one thing we 
> might encourage rather than encourage the fakes.
> 
> I too have considered the 58503, but consider the price disproportionate to 
> what the Z3801A gives me.

Even the “real genuine original” Z38xx and 58xxx boxes differ mainly in the 
power supply area. The firmware and performance differences are minor.

> 
> So, let's stop this thread of hurt feelings, while it has been interesting 
> and enlightening, we can't get very much more right now. Let's open our boxes 
> and try to see the modifications we can do, collect them on a webpage for 
> everyone to enjoy and use, and be done with it.

Or one could buy the KS boxes that are known *not* to be fakes / have the same 
basic performance and move on in that direction with web pages etc….

Bob

> 
> Cheers,
> Magnus
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Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...

2014-12-14 Thread Neil Schroeder

The oscillator in he m8f is a vctcxo and can be steered with feedback or
controlled by the host.

Also the m8f can send compliant DAC words to a TLV8515 and and MCP part via
i2c for external
VCXOs. It accepts their return signal on what would normally  be its
feedback in ports.

On Sunday, December 14, 2014, Bob Camp  wrote:

> Hi
>
> There is also a little note down in the (many) notes section:
>
> Not all features are available with all firmware versions.
>
> It applies to all of the external inputs (like USB and SPI).
>
> Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding
> feature would not help in the case of biasing the unit with a hot air gun.
> It would still loose lock as the TCXO went nuts.
>
> The ideal outcome would be a system that reported against the external
> input rather than the internal TCXO. Since they digitize the external pin
> with the TCXO, the outcome is pretty coarse (10’s of ns). That’s not going
> to help us much.
>
> Bob
>
> > On Dec 14, 2014, at 4:26 AM, Simon Marsh  > wrote:
> >
> >
> > On 14/12/2014 04:08, d...@irtelemetrics.com  wrote:
> >> > Note that most high-end GNSS timing receivers go one better and
> simply have an external input for the clock. That way you feed your own lab
> clock into the receiver. If you have Rb/Cs/maser you would use that as the
> reference. It's what the national timing labs do, along with dual-frequency
> and post-processing and all the other tricks of the trade.
> >
> >> I think it would be agreat idea also. It's a wonder that more of the
> 'timing' receivers don't have that external clock option! I wonder what
> these Ublox parts use for a clock? Is it something frequency compatible
> with a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) )
> >
> > Ublox modules have a 48mhz internal clock.
> >
> > There is the following interesting paragraph in at least the 7 & 8 data
> sheets:
> >
> > ---
> >
> > 1.8.2 Aiding
> > The EXTINT pin can be used to supply time or frequency aiding data to
> the receiver.
> >
> > For time aiding, hardware time synchronization can be achieved by
> connecting an accurate time pulse to the EXTINT pin.
> >
> > Frequency aiding can be implemented by connecting a periodic rectangular
> signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high
> phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide
> the applied frequency value to the receiver using UBX messages.
> >
> > ---
> >
> > I haven't been able to find any information about what this actually
> does though. Anyone know ?
> >
> > Cheers
> >
> >
> > Simon
> > ___
> > 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.
>
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Re: [time-nuts] Which First GPSDO to buy?

Hi

> On Dec 14, 2014, at 12:47 AM, Chris Albertson  
> wrote:
> 
> I tried to see just how simple, low cost and self contained I could make a
> GPSDO.  I started with the Lars Walenius design then removed everything I
> could from it.  I replace all the software with just a small loop with
> about a dozen lines of code so it would be easy to understand.
> 
> My goal was to make something that could be built and tested using just
> basic equipment.  The question is of course "How do you know the unit is
> making a 10 MHz signal if you don't already have a 10MHz reference to
> compare it to?"  Well you can assume that your 1PPS reference is accurate.

Except that the GPS PPS is *not* perfect, far from it. It’s only reasonably 
accurate over very long time spans. Over short spans the pps moves around a lot.

> Then you count and make sure you see EXACTLY 10,000,000 oscillator cycles
> per each PPS.  

If you do a tight lock (“EXACTLY”)  against a GPS PPS that is moving +/- 10 ns, 
your frequency will swing +/- 1x10^-8 every second

> Count both for a few days and verify the ratio remains at
> ten million to one, exactly.

Ok, that’s looking at the long term where GPS is indeed accurate. That’s the 
easy part on any GPSDO design. 

>  I ran mine for about 8 weeks and it stays at
> the desired ratio.I know this is not a perfect test because it could
> have been running at zero hertz for 30 seconds and then 20MHz for 30
> seconds but I assume the OCXO is better than that.   The point is that once
> you have the GPS working you DO have a  pretty good 1Hz reference.

Well, not quite so fast. You just jumped over a massive amount of work that 
normally gets done on a GPS. A unit that *was* swinging +/- 1x10^-8 every 
second would pass your test. (which is not in any way to say that your design 
actually does that).  It would make a lousy GPSDO for most uses. You very much 
*do* need to check the ADEV (or what ever) close in and tune your filter up to 
match your parts.  

> 
> Cost:
> Motorola Oncore GPS$18
> magnnetic patch antenna   6
> OCXO (eBay)   19
> Arduino, mini  3
> PLL chip 2
> TTL diver chip1
> Plug-in power cube0
> perf-board  1
> 
> Total cost of GPSDO $50

Just a side note - A *lot* of the $19 OCXO’s I have from eBay are in very poor 
shape spec wise. Testing them before using them would be a very good idea. 

Bob


> 
> Actually I do have A Thunderbolt.  I place the 10MHz output of the above
> unit and the TB on my dual channel scope and was able to see the phase of
> the two 10MHz references was locked.  I saw the phase drift over about an
> hour but then it would pull back.   But I made this very simple and it
> could be better.
> 
> Actually I've added  some features to it like a 2 line by 16 character LCD
> display and some status LEDs.  And I can log data to a computer via a USB
> cable so it is easy to plot data and it is using my more expansive mast
> mounted timing antenna.
> 
> The Arduino based design is OK for controlling an OCXO but I think it is
> best used for controlling my Rubidium oscillator.  The RB is so stable I
> should only update the frequency control every few hours at most.
> 
> On Sat, Dec 13, 2014 at 7:21 PM, Jim Harman  wrote:
>> 
>> On Sat, Dec 13, 2014 at 9:36 PM, Bob Camp  wrote:
>> 
>>> The problem with “build it yourself” is that there is no way do know if
>>> you got it right unless you have something to compare your design to. You
>>> *will* make mistakes as you build one of these….
>> 
>> 
>> I think you will have the same problem with an off-the-shelf unit if you
>> don't have at least one reference for comparison. However speaking from
>> experience with Lars Walenius' Arduino-based design, I can say that it is
>> not hard to make a working system, even without another reference. Along
>> the way you will learn a tremendous amount about how these systems work,
>> plus a lot about Arduino programming.
>> 
>> Lars' design will run stand-alone, but if you want it can send very useful
>> logging data to a PC, much more informative than a "locked" led on a
>> commercial unit.
>> 
>> Total cost including processor, Adafruit GPS shield, and $25.00 ebay OCXO
>> is about $100.00
>> 
>> 
>> --
>> 
>> --Jim Harman
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>> 
> 
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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[time-nuts] Fake 58503


Fellow time-nuts,

I have seen the long debate about the fake 58503s. Maybe we should take 
a step back and think a little about that. Why does someone rebuild say 
Z3801s into 58503s? Because somehow they are expected to have a higher 
value, and therefore there is a profit to be made in doing so.


Why is there a higher value? Because the potential buys have made that 
decision, sub-consciously. There is a few differences, but to some 
degree they are superficial.


If you want to reduce the likelihood of being fooled by fakes, then 
don't raise certain "magic number" boxes to the skies and prices with it.


I could make better use of my Z3801A if I did a few mods myself, beyond 
the modification from RS422 to RS232. Honest mods and upgrades is one 
thing we might encourage rather than encourage the fakes.


I too have considered the 58503, but consider the price disproportionate 
to what the Z3801A gives me.


So, let's stop this thread of hurt feelings, while it has been 
interesting and enlightening, we can't get very much more right now. 
Let's open our boxes and try to see the modifications we can do, collect 
them on a webpage for everyone to enjoy and use, and be done with it.


Cheers,
Magnus
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Re: [time-nuts] tyco electronics A1025

Hi

> On Dec 14, 2014, at 6:03 AM, Francesco Messineo 
>  wrote:
> 
> Hi all,
> I've just found an old anti-theft system (I think) for cars . It has a tyco
> electronics A1205 gps module.
> I've been unable to find any information about this module, other than it
> should be a 3.3V 12 channel GPS module with serial NMEA output.
> Does anyone have any informations about it? Even a pinout would help. I'd
> like to use it as a cheap NMEA receiver for a stratum 1 ntp server.
> Thanks in advance.

It’s unlikely that a consumer targeted GPS has a good dedicated PPS out of it. 
Finding one that will do position hold is even less likely. You can get modules 
that will do both for < $20 and have a documented interface. 

Bob

> 
> Frank IZ8DWF
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Re: [time-nuts] Ublox time/freq aiding was Re: Linear voltage regulator hints...

Hi

There is also a little note down in the (many) notes section:

Not all features are available with all firmware versions. 

It applies to all of the external inputs (like USB and SPI).

Since the oscillator in the uBlox is a TCXO and not a VCTCXO, the aiding 
feature would not help in the case of biasing the unit with a hot air gun. It 
would still loose lock as the TCXO went nuts. 

The ideal outcome would be a system that reported against the external input 
rather than the internal TCXO. Since they digitize the external pin with the 
TCXO, the outcome is pretty coarse (10’s of ns). That’s not going to help us 
much.

Bob

> On Dec 14, 2014, at 4:26 AM, Simon Marsh  wrote:
> 
> 
> On 14/12/2014 04:08, d...@irtelemetrics.com wrote:
>> > Note that most high-end GNSS timing receivers go one better and simply 
>> > have an external input for the clock. That way you feed your own lab clock 
>> > into the receiver. If you have Rb/Cs/maser you would use that as the 
>> > reference. It's what the national timing labs do, along with 
>> > dual-frequency and post-processing and all the other tricks of the trade.
> 
>> I think it would be agreat idea also. It's a wonder that more of the 
>> 'timing' receivers don't have that external clock option! I wonder what 
>> these Ublox parts use for a clock? Is it something frequency compatible with 
>> a 10Mhz source??? (Hmm, can we pry one apart to figure it out! ;) ) 
> 
> Ublox modules have a 48mhz internal clock.
> 
> There is the following interesting paragraph in at least the 7 & 8 data 
> sheets:
> 
> ---
> 
> 1.8.2 Aiding
> The EXTINT pin can be used to supply time or frequency aiding data to the 
> receiver.
> 
> For time aiding, hardware time synchronization can be achieved by connecting 
> an accurate time pulse to the EXTINT pin.
> 
> Frequency aiding can be implemented by connecting a periodic rectangular 
> signal with a frequency up to 500 kHz and arbitrary duty cycle (low/high 
> phase duration must not be shorter than 50 ns) to the EXTINT pin. Provide the 
> applied frequency value to the receiver using UBX messages.
> 
> ---
> 
> I haven't been able to find any information about what this actually does 
> though. Anyone know ?
> 
> Cheers
> 
> 
> Simon
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Re: [time-nuts] KS-24361 quirk

Hi

The cell phone base only needs one reference to keep it running. They disable 
the un-needed output to make it clear which one should be used. It’s a very 
common thing in modern systems, not just telecom setups.

Bob

> On Dec 13, 2014, at 11:55 PM, Hal Murray  wrote:
> 
> Can somebody confirm that the PPS and 15 MHz on the standby unit are disabled?
> 
> Does anybody understand how/why they do things that way?  Is that a typical 
> Telco interface?
> 
> 
> If anybody is poking around inside and find a simple way to turn them back 
> on, please share.
> 
> 
> The PPS is 400 microseconds wide.
> 
> 
> -- 
> These are my opinions.  I hate spam.
> 
> 
> 
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Re: [time-nuts] KS-24361 quirk

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

I haven't checked the pps either. But the reason to put the 15 Mhz into
standby is that they combine both signals in a resistive combiner and
distribute the signals to multiple radios.
If two were active it would create issues. This method avoids the gap
switch of a relay.
Regards
Paul
WB8TSL

On Sun, Dec 14, 2014 at 12:23 AM, Joseph Gray  wrote:
>
> I haven't checked the PPS yet, but the 15 MHz from the standby unit is
> off on my setup.
>
> Joe Gray
> W5JG
>
>
> On Sat, Dec 13, 2014 at 9:55 PM, Hal Murray 
> wrote:
> > Can somebody confirm that the PPS and 15 MHz on the standby unit are
> disabled?
> >
> > Does anybody understand how/why they do things that way?  Is that a
> typical
> > Telco interface?
> >
> >
> > If anybody is poking around inside and find a simple way to turn them
> back
> > on, please share.
> >
> >
> > The PPS is 400 microseconds wide.
> >
> >
> > --
> > These are my opinions.  I hate spam.
> >
> >
> >
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

On 14 December 2014 at 13:37, bownes  wrote:
>
>
>> On Dec 14, 2014, at 07:42, Dr. David Kirkby (Kirkby Microwave Ltd) 
>>  wrote:
>>
>>> On 14 December 2014 at 11:57, Hal Murray 
> 
>>
>> That command works.
>>
>> How do you reboot - apart from of course powering the thing off?
>>
>
> # shutdown -y -i6 -g0
>
> Or
>
> # reboot
>
> Or
>
> # init 6
>
> Bob

I know those commands, although I don't recommend "reboot" - it is
less clean than init 6. I assumed that that Hal Murry's "reboot" was
meant to be the GPS receiver, not the Solaris computer, but maybe I
mis-understood.

Dave
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

On 14 December 2014 at 12:39, Neil Schroeder  wrote:
> Based on my recent testing - including Solaris - you will be better off
> with the Internet unless your USB adapter is far better behaved than the
> several I have here

The USB -> serial adapter I have is an Keyspan USA-19HS

http://www.tripplite.com/high-speed-usb-to-serial-adapter-keyspan~USA19HS/

I bought that one, as it was officially supported by Sun. I also have
another one somewhere - forget which model. Again that was officially
supported by Sun.

Both have worked for industrial control applications, whereas I gather
some cheap ones are only suitable for common consumer devices.

In any case, it will be more fun & educational to use the GPS
receiver. To be honest, I don't need great accuracy. I only bought the
unit as a frequency standard - the clock functionality is not
important to me, but if I can have a bit of fun playing around with
it, then I will.

Dave
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

2014-12-14 Thread bownes

> On Dec 14, 2014, at 07:42, Dr. David Kirkby (Kirkby Microwave Ltd) 
>  wrote:
> 
>> On 14 December 2014 at 11:57, Hal Murray  

> 
> That command works.
> 
> How do you reboot - apart from of course powering the thing off?
> 

# shutdown -y -i6 -g0

Or

# reboot

Or

# init 6

Bob
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

2014-12-14 Thread Dr. David Kirkby (Kirkby Microwave Ltd)

On 14 December 2014 at 11:57, Hal Murray  wrote:
>
> drkir...@kirkbymicrowave.co.uk said:
>> Can anyone advise if this is possible,  and if so what software is needed?
>> Any idea what sort of accuracy would be achievable?
>
> I'm not familiar with Solaris.  I've never worked with a 58503A, but I have
> worked with the Z3801A and KS-24361.
>
> I'd try ntpd.  There is probably a version that comes with Solaris.

I

1) Downloaded ntp-4.2.6p5
2) Configured with as  ./configure --enable-HPGPS
3) Built it, without any problems.
4) Switched user to root
4) Disabled the ntpd which was already running

# svcadm disable ntp

4) Installed it. I found it created a number of files in /usr/local/bin

drkirkby@buzzard:~$ ls -lrt /usr/local/bin/ | grep  "Dec 14"
-rwxr-xr-x   1 root root1394 Dec 14 12:19 ntp-wait
-rwxr-xr-x   1 root root2029 Dec 14 12:19 ntptrace
-rwxr-xr-x   1 root root  466252 Dec 14 12:19 sntp
-rwxr-xr-x   1 root root 2253412 Dec 14 12:19 ntpd
-rwxr-xr-x   1 root root  299696 Dec 14 12:19 ntpdate
-rwxr-xr-x   1 root root  604280 Dec 14 12:19 ntpdc
-rwxr-xr-x   1 root root  606312 Dec 14 12:19 ntpq
-rwxr-xr-x   1 root root  176496 Dec 14 12:19 ntptime
-rwxr-xr-x   1 root root   23288 Dec 14 12:19 tickadj
-rwxr-xr-x   1 root root  460120 Dec 14 12:19 ntp-keygen

and also the directory /dev/fd

drkirkby@buzzard:~$ ls /dev/fd
0112  127  141  156  170  185  2213  228  242  27   41   56   70   85
1113  128  142  157  171  186  20   214  229  243  28   42   57   71   86
10   114  129  143  158  172  187  200  215  23   244  29   43   58   72   87
100  115  13   144  159  173  188  201  216  230  245  344   59   73   88
101  116  130  145  16   174  189  202  217  231  246  30   45   674   89
102  117  131  146  160  175  19   203  218  232  247  31   46   60   75   9
103  118  132  147  161  176  190  204  219  233  248  32   47   61   76   90
104  119  133  148  162  177  191  205  22   234  249  33   48   62   77   91
105  12   134  149  163  178  192  206  220  235  25   34   49   63   78   92
106  120  135  15   164  179  193  207  221  236  250  35   564   79   93
107  121  136  150  165  18   194  208  222  237  251  36   50   65   894
108  122  137  151  166  180  195  209  223  238  252  37   51   66   80   95
109  123  138  152  167  181  196  21   224  239  253  38   52   67   81   96
11   124  139  153  168  182  197  210  225  24   254  39   53   68   82   97
110  125  14   154  169  183  198  211  226  240  255  454   69   83   98
111  126  140  155  17   184  199  212  227  241  26   40   55   784   99
drkirkby@buzzard:~$


> USB probably doesn't support PPS.  I'd expect time to be within ballpark of
> 10s of ms, roughly what you would expect with a good network connection so
> use that as a sanity check.
>
> You will need to setup your ntp.conf to use the HP driver, 26.

That I am not sure how to configure ntp.conf - a case of RTFM.

> You will need to setup your 58503A to use UTC in T2 mode.
>   :diag:gps:utc 1  (and reboot?)

That command works.

How do you reboot - apart from of course powering the thing off?

>   :ptime:tcode:format F2

That command works too.

> You can check the GPS/UTC setting on the status page, and check the T2
> setting by sending:
>   :PTIME:TCODE?

E-101>  :PTIME:TCODE?
T220141214123441337
(remember I have not rebooted)


Dave
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Re: [time-nuts] Set time on Solaris computer from HP 58503A

2014-12-14 Thread Neil Schroeder

Based on my recent testing - including Solaris - you will be better off
with the Internet unless your USB adapter is far better behaved than the
several I have here

On Sunday, December 14, 2014, Hal Murray  wrote:

>
> drkir...@kirkbymicrowave.co.uk  said:
> > Can anyone advise if this is possible,  and if so what software is
> needed?
> > Any idea what sort of accuracy would be achievable?
>
> I'm not familiar with Solaris.  I've never worked with a 58503A, but I have
> worked with the Z3801A and KS-24361.
>
> I'd try ntpd.  There is probably a version that comes with Solaris.
>
> USB probably doesn't support PPS.  I'd expect time to be within ballpark of
> 10s of ms, roughly what you would expect with a good network connection so
> use that as a sanity check.
>
> You will need to setup your ntp.conf to use the HP driver, 26.
>
> You will need to setup your 58503A to use UTC in T2 mode.
>   :diag:gps:utc 1  (and reboot?)
>   :ptime:tcode:format F2
>
> You can check the GPS/UTC setting on the status page, and check the T2
> setting by sending:
>   :PTIME:TCODE?
>
>
>
> --
> These are my opinions.  I hate spam.
>
>
>
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Re: [time-nuts] Which First GPSDO to buy?

2014-12-14 Thread Patrick Tudor

> On Dec 13, 2014, at 9:47 PM, Chris Albertson  
> wrote:
> 
> Actually I've added  some features to it like a 2 line by 16 character LCD
> display and some status LEDs.  And I can log data to a computer via a USB
> cable so it is easy to plot data and it is using my more expansive mast
> mounted timing antenna.

Just in case any of you like reading Arduino code, for fun or functions to 
copy-and-paste,
the code for my PCB that combines an ATMega328p with an Adafruit GPS and 
16x2 LCD to display GPS info as it sends the PPS out the DB9 DCD is at GitHub.
It’s not exactly, say, measuring oscillator cycles (yet... ) but it’s perhaps
a good introduction for someone who’s never ever before used anything Arduino.
(And now that I’ve done more PCBs with Cypress and FTDI chips, I wish I’d put 
that straight on my board instead of as a future daughterboard, but, feature 
creep.)

https://github.com/ptudor/jemma-clock

PT

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Re: [time-nuts] Set time on Solaris computer from HP 58503A