Re: [time-nuts] Fluke Voltage Standards.

[xaos]

I wonder if there is a way to get a voltage standard out of a frequency
standard (GPS Disciplined).
I think the big problem is probably voltage stability due to temperature
variations.

Any thoughts on this ?

-George


On 11/10/2016 02:17 PM, paul swed wrote:
> Perry,
> Thanks for pointing them out. Very tempting. But that said what I really
> liked was the 2012 tour pixs on the site.
> I would have some serious fun going through that place and loading up my
> trunk.
> But thats 11 drive hours away. Maybe not this week.
> I have purchased various items from Fair Radio and though I am sure you
> could get burned the fact is I never have been. They are pretty upfront on
> the risk.
> The killer for me is the shipping on about anything they have costs more
> then the usable value of the equipment. He at ham prices.
> Regards
> Paul
> WB8TSL
>
> On Thu, Nov 10, 2016 at 2:32 AM, Bill Hawkins  wrote:
>
>> Had the HP equivalent for a while. Required special cords to bring the
>> voltage to the DUT. Buyer Beware.
>> Haven't seen a Fair Radio catalog in years, not since I sold the R-39x
>> equipment.
>>
>> There's a big difference between the accuracy of a voltage standard and
>> a time standard.
>> Perhaps this is because there are no satellites broadcasting voltage
>> standards.
>>
>> Bill Hawkins
>>
>>
>> -Original Message-
>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry
>> Sandeen via time-nuts
>> Sent: Wednesday, November 09, 2016 6:26 PM
>>
>> List,
>> Fair Radio which has been in the surplus electronics business almost
>> forever has two models of Fluke standards for sale. They have a sterling
>> reputation.
>> FLUKE-332A  $100 Voltage Standard - Used Reparable
>>
>> FLUKE-332B  $125 Voltage Standard - Used Reparable
>>
>>
>> IIRC, this means they will work but are not calibrated.  If interested
>> one can email them for exactly what Used Repairable means.
>> FWIW
>> Regards,
>> Perrier
>>
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[time-nuts] IEEE article on Judah Levine

[xaos]

Nice article on NIST and NTP.

http://spectrum.ieee.org/tech-talk/computing/networks/meet-the-guy-whose-software-keeps-the-nations-clocks-in-sync

-GKH
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Re: [time-nuts] GPS jumps of -13.7 us?

[xaos]

Slashdot got it.

http://it.slashdot.org/story/16/01/26/1735223/discrepancy-detected-in-gps-time

On 01/26/2016 12:20 PM, Scott Newell wrote:
> At 09:12 AM 1/26/2016, Paul Boven wrote:
>
>> Has anyone else seen GPS time jump by -13.7 usec today?
>
> My tbolt locked ntp server saw an unusual spike of about that
> magnitude just after 00:00 1-26-2016 UTC. (The bump at 4 seconds
> is from the daily backup run.)
>
>
>
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[time-nuts] AGC or manual attenuator

[xaos]

Hello everyone,

In the past there have been several posts about
amplifier input and AGC. As many have pointed out
this is always a bad idea since the AGC circuit
tends to add phase noise, etc.

So my question today is: Is this still true?

My old Panoramic spectrum analyzer (yeah, she's a beauty!)
has a very nice input attenuator which you select
manually.

Is this my only option? Digital pots don't usually go above
1 MHz, and if they did, are they an option?

George Hrysanthopoulos, N2FGX

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Re: [time-nuts] Divider circuit for Rubidium Standard

[xaos]

After reading the posts on this subject I have a question.
First, in my experience I used a rather simple circuit made from
diodes used as limiters and a transistor feeding
a logic inverter. No AGC.

So here is my question. What is the proper circuit to use?
I'd like to do a PSPICE and check things out followed by
a prototype.

I got that a comparator is out, etc.

Cheers,
George H. N2FGX

On 04/26/2015 06:51 AM, Bryan _ wrote:
 All:

 Picked up a FE 5680B from Ebay awhile back. Appears to work fine, but is 
 limited to a 1pps output. However there is a point on the PCB that's 
 documented that has a 20Mhz output. There is actually a clean 60Mhz output as 
 well.

 http://www.ebay.com/itm/FEI-fe-5680b-rubidium-oscillator-With-1pps-20mhz-output-ONLY-10mhz-NEED-to-MOD-/291419889143?pt=LH_DefaultDomain_0hash=item43d9fa9df7

 I would like to tap this 20mhz output and feed it to a divider/buffer circuit 
 for a 10Mhz output at 50ohm. Can anyone recommend a good schematic for such a 
 purpose. I was looking at the project from David partridges web site 
 http://www.perdrix.co.uk/FrequencyDivider/index.html

 Cheers and thanks in advance.

 -=Bryan=-   
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Re: [time-nuts] Divider circuit for Rubidium Standard

[xaos]

Bob,

This are all great questions.

1. Let's assume that it varies from a HP Signal generator
to a home built device. However, If I was to build it I
would expect to pay more and get better specs.
I have a few HP 3325B's and a few 8660C.
I would probably use those as inputs but not always.

2. Let's stick with the basics: 5-10Mhz.

3. Again, basics: 1-7V peak to Peak.

4. Ok, this is the real important question.
The answer is, an amplifier of some sort.
And that amp will probably feed something
like a Test Instrument or some circuit I
am building. What are my options?

For now, I'd like to simulate some of my simple
designs as well as some designs suggested here.
Then, see where it goes.

George


On 05/22/2015 05:31 PM, Bob Camp wrote:
 Hi

 What is your objective? Put another way:

 1)  How clean is your sine wave source? 
 2) What frequency (or range) are you trying to convert?
 3) What level range are you trying to work with?
 4) What is it going into (how clean is the next stage)?

 If you have an optical fountain that is good to 1x10^-15 at 1 second, and
 you are trying to map Pluto with a radar in your back yard, the answer will
 be a bit different than if you are starting with a surplus OCXO and trying 
 to drive a 5334 :)

 Bob

 On May 22, 2015, at 4:27 PM, xaos x...@darksmile.net wrote:

 After reading the posts on this subject I have a question.
 First, in my experience I used a rather simple circuit made from
 diodes used as limiters and a transistor feeding
 a logic inverter. No AGC.

 So here is my question. What is the proper circuit to use?
 I'd like to do a PSPICE and check things out followed by
 a prototype.

 I got that a comparator is out, etc.

 Cheers,
 George H. N2FGX

 On 04/26/2015 06:51 AM, Bryan _ wrote:
 All:

 Picked up a FE 5680B from Ebay awhile back. Appears to work fine, but is 
 limited to a 1pps output. However there is a point on the PCB that's 
 documented that has a 20Mhz output. There is actually a clean 60Mhz output 
 as well.

 http://www.ebay.com/itm/FEI-fe-5680b-rubidium-oscillator-With-1pps-20mhz-output-ONLY-10mhz-NEED-to-MOD-/291419889143?pt=LH_DefaultDomain_0hash=item43d9fa9df7

 I would like to tap this 20mhz output and feed it to a divider/buffer 
 circuit for a 10Mhz output at 50ohm. Can anyone recommend a good schematic 
 for such a purpose. I was looking at the project from David partridges web 
 site http://www.perdrix.co.uk/FrequencyDivider/index.html

 Cheers and thanks in advance.

 -=Bryan=- 
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Re: [time-nuts] New GPSDO on EBAY From China

[xaos]

You have to give the guy credit for trying.
What is a shame here is that he did not
publish the schematics and the source code.

If anyone knows him he should just ask him. We tend to
be sceptics here but that's the nature of the game.
However, I don't want anyone to think that we are elitist.

I remember my first GPSDO, by Brooks Sherra,
on QST. I remember reading the schematic and the
source code many times until I got it. It
is the reason I got interested in time-nuts
to begin with.

So, I think we would all benefit from going a bit
deeper on this new unit. I hope the designer
is reading this.

GKH, N2FGX

On 12/29/2014 12:50 AM, Charles Steinmetz wrote:
 Li Ang wrote:

 This unit is done by BG7TBL. In his store on taobao.com,
 there is a adev chart. Please refrer to this link

 That ADEV chart (see below) raises more questions than it answers.  At
 least the time constant is not too short (a very common problem with
 DIY GPSDOs).  But when the GPS takes over above the crossover (tau ~
 5000 seconds), the ADEV is ~2e-11.  GPS should be significantly better
 than this at 5000 seconds.  It appears that something is wrong with
 the design.

 Best regards,

 Charles



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Re: [time-nuts] gravity, space and time

[xaos]

When LIGO was announced I read up on it as much as I could.
The problems seemed enormous.

Bob Darlington mentioned shock mounts. That in itself seemed
like a show stopper.

Then I think there was some kind of accident. Anyway
these guys did finish the LIGO. But unfortunately
no space differential was measured. What an incredible
experiment.

-G

On 12/12/2014 04:31 PM, Mark Sims wrote:
 My Mickey Mouse watch was...  it detected a gravity anomaly when the strap 
 broke and it hit the garage floor.  This apparently caused a complete 
 cessation of temporal flow around the unit,   ;-)

 -
 Our clocks aren't good enough.  
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[time-nuts] HOWTO Stratum 1 NTP server under CentOS 7

[xaos]

Hello everyone,

If anyone is interested, I have created a HOWTO
on running a Motorola GPS receiver connected to
a CentOS 7 box via serial port (com1), with 1PPS over DCD.

Here is the documentation.

http://www.maximaphysics.com/Centos_7_GPS_Setup.html

Let me know if something does not look right.

-George, N2FGX
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Re: [time-nuts] Linear voltage regulator hints...

[xaos]

I don't know if this is the right time to ask this but here goes.
I have started a design for a linear power supply for the Beagleboard

5V 5-10A. Over-Voltage, short circuit and temp protection.
Very low ripple and HF noise.

I have been watching this thread and I am still not sure
what device would give me what I want. I am not as good as
some circuit designers here, to design a PS
via discreet transistors. Dr. Bruce Griffiths comes to mind.
He would probably do this with his eyes closed.

So, I need to use a regulator chip.

The TI TPS7A4700 looks great but it can only supply 1A.

Any other candidates ?

I am sorry if I am somehow asking an obvious question.

-George

On 12/11/2014 06:26 PM, Neil Schroeder wrote:
 So I've done a lot of work in power lately and I can summarize some of this
 quickly:

 The lowest noise LDOs today are the TI TPSa4700/01 up to 36v/1a and about 4
 uVRms noise,  and the ADP7154/55 up to 5.5v and 600ma with only *0.9* uVRms
 above 100hz.

 Both feature great PSRR -and in the case of the ADI part don't even
 recommend filter caps at all.

 The TI however does still recommend some capacitance.

 Now most people's next question  is how to get their ruby or their
 septuple-oven homebrew design powered by one. The quick answer is an error
 amplifier based ldo balancer for the most accurate distribution of current.
 Also helps with heat.

 Will share a sketch when at my desk next.


 On Thursday, December 11, 2014, Hal Murray hmur...@megapathdsl.net wrote:

 e...@telight.com javascript:; said:
 If the plan is to use a three-terminal regulator after all, I'd  suggest
 not
 using a low-dropout (LDO) type if the raw input supply is  noisy - the
 LDOs
 usually have PNP output transistors (for positive  regulators), so may
 tend
 to have poorer HF input ripple rejection  than equivalent ones with NPN
 passers.
 In this context, what is high?

 Why don't filter caps solve that end of the spectrum?


 --
 These are my opinions.  I hate spam.



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Re: [time-nuts] Beaglebone NTP server

[xaos]

Brian,

Sorry about the long post.

I was on a similar path recently. I wanted to create
a nice and simple Stratum 1 server using a beagleboard.
In addition, I wanted to create a nice case for it
so I would enjoy looking at it from my desk.

Since I was already using a GPS Motorola receiver to
create a Linux NTP server, I was pretty sure I had most of
the parts.

Since The Beagleboard is using systemd I figured I would
start by creating a CentOS 7 Stratum 1 machine so I can
figure out all the systemd pieces.

I finished this 5 days ago.

Next, using Cadence Allegro (OrCAD) I designed a
proto cape for the Beagleboard.

This is also done. I figure I will use the proto cape
as a prototype board and also get familiar with
all the pins on the Beagleboard I/O headers.

This is also done (mostly) as of yesterday.

Actually, I was in the middle of documenting this
when this thread caught my eye.

You and everyone on this list are welcome
to the Cadence Project and all the files.
You can use this basic project to design any cape
for the Beagleboard. I am releasing it as free.
Just mention my company: Maxima Physics.

I will finish the documentation for CentOS 7 + NTP
server over the next few days. I have also been fighting
a nasty flu :(

Comments are most welcome.

-George Hrysanthopoulos


On 12/10/2014 04:58 PM, Brian Lloyd wrote:
 Well, I am hoping to get to the point where the path to using the BBB as an
 NTP server using the PRU for more precise timing, and using the LTE-lite to
 provide the 1pps and time data. Of course, the LTE-lite can also provide
 1pps and 10MHz to my workbench. (It's all going to go in a 1U box in the
 rack next to my workbench.)

 Yes, I know that all the information is out there and much if it can be
 gleaned from this list by following several threads back through several
 months. But that brings to mind playing Adventure. Has anyone compiled a
 how-to for turning a BBB into an NTP server using the PRU for timing? Seems
 like a straight-forward and useful turn-key kind of thing.


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[time-nuts] CentOS 7, Motorola GPS receiver and NTP

[xaos]

Hello everyone.

Currently my Stratum 1 NTP server is made up of the following:

Pentium 4 Motherboard, Single core, 1.4GHz., 1GB memory
Slackware Linux, 11.0.0
PPSkit-2.1.7 Kernel
uname -a:
Linux timelord 2.4.33.3-NANO #1 Fri Nov 12 21:28:51 EST 2010 i686
pentium4 i386 GNU/Linux

Motorola, GPS Receiver Version: 3, Revision: 1, Software Date: 1A30,
Model: R5222U1114/[UT], Serial: R0AZSU

As far as I know the PPSKit was never released for the
later kernels and this machine is showing it's age.
I want to get a new box and run CentOS 7 on it.

Question: How do I setup NTP with a 1 PPS from serial port
and the Motorola receiver hooked up?

I hope that some here have done this already and
I wont have to start from scratch.

I was thinking about the Atom driver?
How do I tell the driver to use the data from the serial port?

Any help would be greatly appreciated.

George, N2FGX

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Re: [time-nuts] Yet another GPSDO

[xaos]

This is the strangest unit I have ever seen.
No documentation.

Morion OCXO
http://www.morion.com.ru/eng/
From St. Petersburg :)

I cant make out any part number.
except this number on the front panel:

06109a_y145_09

Google gives me nothing.

I might buy one just for the hell of it.

-George
On 11/18/2014 06:23 PM, Arthur Dent wrote:
 I just noticed this on Ebay. The seller has several other related
 items but the pricing is kind of confusing. No a lot of info.

 http://www.ebay.com/itm/GPS-DISCPLINED-CLOCK-GPSDO-10M-OUTPUT-SQUARE-WAVE-/111514491254

 -Arthur
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Re: [time-nuts] Yet another GPSDO

[xaos]

Well, how about this:
http://www.cart100.com/Product/42336500072/

Same unit as eBay about 10 bucks cheaper.

-G


On 11/18/2014 07:03 PM, Pete Lancashire wrote:
 The other marking on the unit is BG7TBL

 do a Google search of images, interesting

 Wonder who it is ?

 -pete

 On Tue, Nov 18, 2014 at 3:34 PM, xaos x...@darksmile.net wrote:
 This is the strangest unit I have ever seen.
 No documentation.

 Morion OCXO
 http://www.morion.com.ru/eng/
 From St. Petersburg :)

 I cant make out any part number.
 except this number on the front panel:

 06109a_y145_09

 Google gives me nothing.

 I might buy one just for the hell of it.

 -George
 On 11/18/2014 06:23 PM, Arthur Dent wrote:
 I just noticed this on Ebay. The seller has several other related
 items but the pricing is kind of confusing. No a lot of info.

 http://www.ebay.com/itm/GPS-DISCPLINED-CLOCK-GPSDO-10M-OUTPUT-SQUARE-WAVE-/111514491254

 -Arthur
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Re: [time-nuts] Yet another GPSDO

[xaos]

The cheaper unit has no patch wires. Interesting.
Seems that he put a lot of work in the unit.
Too bad the information on the software is non-existent.

Cheap enough though.

-G

On 11/18/2014 07:24 PM, Bob Camp wrote:
 Hi

 I’d say this has the look of a hobby / semi-pro project. I’ve seen several of 
 them done in other areas. Somebody comes up with a pile of parts at the local 
 market and does a board that at least sort of makes them work. Often they are 
 based on some sort of open source effort.  Without more information, this is 
 very much a “who knows” sort of thing.

 Bob

 On Nov 18, 2014, at 7:19 PM, Arthur Dent golgarfrinc...@gmail.com wrote:

 You can see a similar product by this seller direct -

 http://www.cart100.com/seller/bg7tbl/
 http://www.cart100.com/Product/38848104218/

 Looks like a similar product at almost 3 time the Ebay price.
 There are more photos at the second link under 'specifications'
 and you can read MV89A on the Morion oscillator and see some
 wires patching an error on the bottom of the PC board. Note that
 the seller also has a frequency doubler at about $10.

 -Arthur
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Re: [time-nuts] Quad Driven Mixer 5 to 10 MHz Doubler Article

[xaos]

Luciano,

I will put this in OrCAD/CADENCE PSPICE over the weekend
and see what it looks like.

-George

On 11/14/2014 02:53 AM, tim...@timeok.it wrote:
 George,

 you can replace the input transformer with the mini-circuits model 
 T2-613-1-KK81 or T662-KK81 for under 2 Dollars. The inductors L1 and L3 are 
 standards value you can find smd or standard  on ebay. About L4 you can put 
 in place a standard 4.7uH value increasing the series capacitor for the 5MHz 
 notching.The 3.18uH is critical because  it has the double function of low 
 pass filter and impedance adapter, so I suggest to made it as described or 
 using a smaller core.

 Luciano




 On Thu 13/11/14  3:30 PM , xaos x...@darksmile.net wrote:

 Luciano,

 This looks very nice. However, the inductors are
 custom made. It would be nice to have a
 off the shelf parts solution so it can be made
 easily.

 Any ideas ?

 -George, N2FGX
 On 11/13/2014 08:39 AM, tim...@timeok.it wrote:
 Hi all,

 I can suggest a different solution I have tested to have some important
 improvement. First, the lower phase shift sensitivity with the use of a low
 pass filter in conjunction with two notch filters instead the high Q band
 pass filter, second the unity gain to avoid a 13/20 dB amplifier to restore
 the original power level. You can find in the link all the test we have
 done.
 http://www.timeok.it/files/high_performance_frequency_doublerv13.pdf [1]

 I hope this can hep.

 Luciano
 www.timeok.it [2]




 On Thu 13/11/14 10:15 AM , Bert Kehren via time-nuts  wrote:

 We are using Wenzel with two filters see attached if it will pass. 20
 Mhz
 is down more than 60 db and 5 MHz 55. Distribution Amp takes care of
 the
 rest.
 Bert Kehren

 In a message dated 11/12/2014 8:13:33 P.M. Eastern Standard Time,
 dgmin...@mediacombb.net writes:

 Just a few days ago, I ordered parts to build a couple of the Wenzel
 2-diode
 doublers, described in the same article as your full-wave diode
 doubler,
 just in time to discover them on Ebay (via slow boat from China), item#
 171511157159. I inspected the components and layout in the picture in
 the
 listing, and it certainly looks like the Wenzel FWB doubler. At $9.99
 USD,
 the price is cheap enough, especially since you get SMA connectors on
 both
 ends. Might have to do a bit of solder work on the SMA connectors if
 you
 want to put it into a little box.
 The listing on the doubler on Ebay says that the low end is 10MHz, but
 I'll
 bet that it will get down to 5MHz quite easily If there's any trouble
 handling a 5MHz input, you could easily use a lower frequency ferrite
 for
 the balun and make it work.
 As you suggest, a BPF on the output and maybe a bit of amplification to
 get
 the level up to a usable level should get you a fairly clean 10 MHz.

 Dave M

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Re: [time-nuts] Quad Driven Mixer 5 to 10 MHz Doubler Article

[xaos]

Luciano,

This looks very nice. However, the inductors are
custom made. It would be nice to have a
off the shelf parts solution so it can be made
easily.

Any ideas ?

-George, N2FGX
On 11/13/2014 08:39 AM, tim...@timeok.it wrote:
 Hi all,

 I can suggest a different solution I have tested to have some important 
 improvement. First, the lower phase shift sensitivity with the use of a low 
 pass filter in conjunction with two notch filters instead  the high Q band 
 pass filter, second  the unity gain to avoid a 13/20 dB  amplifier to restore 
 the original power level. You can find in the link all the test we have done.

 http://www.timeok.it/files/high_performance_frequency_doublerv13.pdf

 I hope this can hep.

 Luciano 
 www.timeok.it




 On Thu 13/11/14 10:15 AM , Bert Kehren via time-nuts time-nuts@febo.com 
 wrote:

 We are using Wenzel with two filters see attached if it will pass. 20 Mhz
 is down more than 60 db and 5 MHz 55. Distribution Amp takes care of the
 rest.
 Bert Kehren

 In a message dated 11/12/2014 8:13:33 P.M. Eastern Standard Time,
 dgmin...@mediacombb.net writes:

 Just a few days ago, I ordered parts to build a couple of the Wenzel
 2-diode
 doublers, described in the same article as your full-wave diode doubler,
 just in time to discover them on Ebay (via slow boat from China), item#
 171511157159. I inspected the components and layout in the picture in the
 listing, and it certainly looks like the Wenzel FWB doubler. At $9.99
 USD,
 the price is cheap enough, especially since you get SMA connectors on both
 ends. Might have to do a bit of solder work on the SMA connectors if you
 want to put it into a little box.
 The listing on the doubler on Ebay says that the low end is 10MHz, but
 I'll
 bet that it will get down to 5MHz quite easily If there's any trouble
 handling a 5MHz input, you could easily use a lower frequency ferrite for
 the balun and make it work.
 As you suggest, a BPF on the output and maybe a bit of amplification to
 get
 the level up to a usable level should get you a fairly clean 10 MHz.

 Dave M

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Re: [time-nuts] Lucent KS-24361 GPSDO arrived today several questions

[xaos]

It seems that this program will not work for Win 7.
Has anyone attempted to decompile this thing?

Maybe re-work a bit and have it run on anything?
-George, N2FGX

On 11/07/2014 01:34 PM, Bob Stewart wrote:
 Hi Bill,

 I think I got my copy here.  I used the bottom one.  I don't know what a 
 58503 is.  it was hard to find, for some reason.  I'm using XP on an old 
 laptop.

 http://www.ko4bb.com/manuals/index.php?dir=05%29_GPS_Timing/SatStat
 Bob
   From: Bill Riches bill.ric...@verizon.net
  To: 'Bob Stewart' b...@evoria.net; 'Discussion of precise time and 
 frequency measurement' time-nuts@febo.com 
  Sent: Friday, November 7, 2014 7:04 AM
  Subject: RE: [time-nuts] Lucent KS-24361 GPSDO arrived today several 
 questions

 Hi Bob and group,

 Where are you obtaining Satstat and what windoze version will it work on?  
 XP, W7 32 or 64 bit?  XP I guess?

 Bill Riches
 Cape May



 -Original Message-
 From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Stewart
 Sent: Friday, November 07, 2014 12:03 AM
 To: Discussion of precise time and frequency measurement
 Subject: Re: [time-nuts] Lucent KS-24361 GPSDO arrived today several questions

 Hi Bob,
 I've been using the Satstat program to send commands.  What I don't 
 understand is why the slave will accept commands such as sat elevation angle 
 and not give an error response.  It gives a response of command complete, 
 but it doesn't change it.  Or is that an indication that both units use the 
 same firmware, and success is actually indicated by the resulting change of 
 the angle?

 BobFrom: Bob Camp kb...@n1k.org
  To: gandal...@aol.com; Discussion of precise time and frequency measurement 
 time-nuts@febo.com
  Sent: Thursday, November 6, 2014 6:07 PM
  Subject: Re: [time-nuts] Lucent KS-24361 GPSDO arrived today several 
 questions


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Re: [time-nuts] Divide by five

[xaos]

As far as I'm concerned there are no more DIP parts.
However, let's not give up yet. Although
I am not a high volume manufacturer, I found
a nice way around it.

First, forget about prototyping by hand. That
ship has left.

So, I use OrCAD/Cadence (CIS/PCB Editor)
from the start in order to create
a proper project. This includes circuit and board.
OrCAD is fantastic in that you can have
revisions, simulation, etc, etc...

Then I use http://pcb123.com/ to make myself a
protoboard (or 4). Pretty cheap for
that volume. ~$50

Then to mount the components, I use
http://www.pnconline.com/
 
I can usually make 2-4 protoboards
for ~$200-300 with all the components.
Depends on count.

OK, so not exactly old school but
I have a very nice prototype. OrCad
also does amazing simulations
on diff pairs, and other cool things.

Ultimately, by thinking of these things ahead
of time and doing the design right I end up saving
considerable time.

On the prototypes, there is usually a few extra
SMD pots but that's ok.

Let's face it. DIPs are done. This is the way now
and we might as well get used to it.

Anyone here who needs help with OrCad,
just ask. I am sure there are a few experts here
as well.

Thanks for listening,

-George, N2FGX

On 11/07/2014 07:37 PM, Bob Camp wrote:
 Hi

 The days of DIP parts are drawing to a close. Most of the DIP’s are now 
 surplus and stocked by odd places here and here. The risk with many places 
 (even major names) is that the part you get isn’t what you think it is. It 
 may be a re-labeled something else pulled off a board in China with a 
 blowtorch. 

 I think that in a lot of ways, you are better off with something in one of 
 the larger SMD packages than a surplus / questionable DIP. The other half of 
 the equation at higher frequencies is good layout. That sort of forces you in 
 the direction of a pc board. Custom boards are now so crazy cheap that doing 
 them for a one off makes sense. 

 Bob

 On Nov 7, 2014, at 4:12 PM, Joseph Gray jg...@zianet.com wrote:

 I need to divide a 125 Mhz clock by five. I have looked on Mouser and every
 chip I find is either obsolete or in SMT. Can anyone recommend a chip that
 is fast enough and comes in DIP?

 Joe Gray
 W5JG
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[time-nuts] There seems to be something missing from this eBay item.

[xaos]

I just cant figure out what it is ;)

http://www.ebay.com/itm/HP-Agilent-5071A-Primary-Frequency-Standard-/191386439159?pt=LH_DefaultDomain_0hash=item2c8f854df7

One obvious question: Are the leftover parts worth anything close to the
opening bid ?

-George, N2FGX
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Re: [time-nuts] There seems to be something missing from this eBay item.

[xaos]

Pete,

You're right. Nothing to lose. I think I'll go for it.

There are a total of 3 5071's for sale. 2 have problems and the other
one has no pictures of power up, etc. Prob DOA.

http://www.ebay.com/itm/HP-Agilent-5071A-Primary-Frequency-Standard-/281405994431?pt=LH_DefaultDomain_0hash=item41851ab5bf
http://www.ebay.com/itm/Agilent-HP-5071A-Primary-Frequency-Standard-Op-001-W30-120Vac-USA-/261213924396?pt=LH_DefaultDomain_0hash=item3cd1902c2c

And the one as mentioned above:

http://www.ebay.com/itm/HP-Agilent-5071A-Primary-Frequency-Standard-/191386439159?pt=LH_DefaultDomain_0hash=item2c8f854df7

-George

On 11/06/2014 02:16 PM, Pete Lancashire wrote:
 I've made the seller offers before, usually takes them. IMake an offer of a
 $100 with a note something like Cesium Tube is missing, all the value is
 in the tube, making offer for spare parts

 They are surplus guys have no idea what the thing is. They have someone
 suggesting the TM vaule based on model number only.

 Can't loose

 -pete

 On Thu, Nov 6, 2014 at 10:16 AM, Dr. David Kirkby (Kirkby Microwave Ltd) 
 drkir...@kirkbymicrowave.co.uk wrote:

 On 6 November 2014 18:09, xaos x...@darksmile.net wrote:
 I just cant figure out what it is ;)


 http://www.ebay.com/itm/HP-Agilent-5071A-Primary-Frequency-Standard-/191386439159?pt=LH_DefaultDomain_0hash=item2c8f854df7
 One obvious question: Are the leftover parts worth anything close to the
 opening bid ?

 -George, N2FGX
 Seems a bit risky to me. $3000 is not an insignificant amount of
 money. If you are interested, drop him a message saying if it does not
 sell, you would offer him X for it. Very often they will take the X.

 I like the bit Voltages as high as 42 VDC are present in this area
 That seems a bit unnecessary.

 Dave
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[time-nuts] NPR Story I heard this morning

[xaos]

This morning, as I was driving to work,
I heard this really cool story on NPR radio here in NYC.

This is the link to the story:

http://www.npr.org/2014/11/03/361069820/what-time-is-it-it-depends-where-you-are-in-the-universe

What a nice way to start the week.

Past stories with similar headlines.

http://www.npr.org/2014/01/24/265247930/tickety-tock-an-even-more-accurate-atomic-clock

Cheers,

George Hrysanthopoulos, N2FGX

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Re: [time-nuts] NPR Story I heard this morning

[xaos]

Small correction: The numbers were 10E-16.

One important concept that was discussed was this:
If the next generation clock was even more accurate
(maybe by an order or two), then no two clocks
can ever agree on the time.

Minute changes in gravity and other factors will
always make each clock completely different.

So, to that I said: WOW! Wait just a damn minute.
I got into this so I can tell time precisely. Now I'm back
to to the beginning.

I know I am exaggerating a bit here but still.

-GKH

On 11/03/2014 11:09 AM, Chris Albertson wrote:
 Yes,  A story about time and frequency standards.  They actually used
 numbers like 10E16 in the story.  Apparently at that level your clock can
 measure a change in elevation of a few centimeters because of the
 relativistic effects of the reduced gravity field in just a few cm.

 On Mon, Nov 3, 2014 at 6:28 AM, xaos x...@darksmile.net wrote:

 This morning, as I was driving to work,
 I heard this really cool story on NPR radio here in NYC.

 This is the link to the story:


 http://www.npr.org/2014/11/03/361069820/what-time-is-it-it-depends-where-you-are-in-the-universe

 What a nice way to start the week.

 Past stories with similar headlines.


 http://www.npr.org/2014/01/24/265247930/tickety-tock-an-even-more-accurate-atomic-clock

 Cheers,

 George Hrysanthopoulos, N2FGX

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Re: [time-nuts] NPR Story I heard this morning

[xaos]

You know, I was thinking that exact same thing as
the story went on.

The one (important) thing I got from Tom's story
was that kids might like the idea of the trip,
but the details might seem boring. Although,
I'm sure, Tom had a blast.

I was planning a similar trip from Astoria Queens, NYC
which is sea level, to Adirondack Mountains, upstate New York.

Never found enough friends to make it tho :(

-GKH


On 11/03/2014 11:40 AM, Bob Stewart wrote:
 Have you read Tom's story about his family trip up Mount Ranier with a Cesium 
 clock?  
 Project GREAT: General Relativity Einstein/Essen Anniversary Test

 Bob
  From: xaos x...@darksmile.net
  To: time-nuts@febo.com 
  Sent: Monday, November 3, 2014 10:17 AM
  Subject: Re: [time-nuts] NPR Story I heard this morning

 Small correction: The numbers were 10E-16.

 One important concept that was discussed was this:
 If the next generation clock was even more accurate
 (maybe by an order or two), then no two clocks
 can ever agree on the time.

 Minute changes in gravity and other factors will
 always make each clock completely different.

 So, to that I said: WOW! Wait just a damn minute.
 I got into this so I can tell time precisely. Now I'm back
 to to the beginning.

 I know I am exaggerating a bit here but still.

 -GKH

   
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Re: [time-nuts] NPR Story I heard this morning

[xaos]

Why Strontium over Caesium?
Is it because it just sounds more hi-tech ? LOL

Maybe stupid question to most here, but I do
not know the answer.

-GKH
 
On 11/03/2014 12:59 PM, Chris Albertson wrote:
 On Mon, Nov 3, 2014 at 8:17 AM, xaos x...@darksmile.net wrote:

 Small correction: The numbers were 10E-16.

 No I think it was one part in 10E16 ;)   But the interesting thing was
 they used numbers rather then saying something like really super ultra
 tiny.

 But you are right, no two clocks will ever agree at that level because they
 will experience different gravitational fields.  At this level the reason
 to have a clock is no longer to tell time.  It is to measure the
 gravitational field.  With an array of many clocks like these we might be
 able to map the density of the interior of the earth or detect black holes
 or who knows what.   I think it opens up a new area of observation.  When
 ever this happens we discover things we never would have thought of.  Maybe
 in 40 years these Strontium oscillators will be mass produced for $2 each.

 Does anyone know how much g changes per cm of altitude?  I'm to lazy to
 figure it out.



 One important concept that was discussed was this:
 If the next generation clock was even more accurate
 (maybe by an order or two), then no two clocks
 can ever agree on the time.

 Minute changes in gravity and other factors will
 always make each clock completely different.

 So, to that I said: WOW! Wait just a damn minute.
 I got into this so I can tell time precisely. Now I'm back
 to to the beginning.

 I know I am exaggerating a bit here but still.

 -GKH

 On 11/03/2014 11:09 AM, Chris Albertson wrote:
 Yes,  A story about time and frequency standards.  They actually used
 numbers like 10E16 in the story.  Apparently at that level your clock can
 measure a change in elevation of a few centimeters because of the
 relativistic effects of the reduced gravity field in just a few cm.

 On Mon, Nov 3, 2014 at 6:28 AM, xaos x...@darksmile.net wrote:

 This morning, as I was driving to work,
 I heard this really cool story on NPR radio here in NYC.

 This is the link to the story:



 http://www.npr.org/2014/11/03/361069820/what-time-is-it-it-depends-where-you-are-in-the-universe
 What a nice way to start the week.

 Past stories with similar headlines.



 http://www.npr.org/2014/01/24/265247930/tickety-tock-an-even-more-accurate-atomic-clock
 Cheers,

 George Hrysanthopoulos, N2FGX

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Re: [time-nuts] RasberryPi, timing and GPS receivers

[xaos]

Tom,

Thank you and nice to be back!
Was working major hours for a while.
Workin' for a living :)

Now, I must confess that this project is sort of a
milestone for me.

Those who hate kids (I know you are out there !)
can stop reading now :)

My daughter, who just turned six, has been very curious
about what I do with all my machines.

I have taught her how to properly solder and she can spot
a cold joint and is very adamant about such things.

So, I have been thinking about making a small project
with lights etc. I don't have that much time
and I also want to experiment with the RPI so,
I can combine projects.

Given that an NTP server will not be as much fun
in terms of lights and so on, but I think
it will be more fun when the intricacies
of time are explained.

She is already very interested in puzzles and stuff
so I figure I'll encourage her.

I was actually very sneaky with getting her
interested in puzzles and stuff.

You see we both love Gravity Falls which is
this amazing Disney Channel series
that has crazy puzzles in it and it is a challenge
to figure out what is hiding in each episode.

Using that as the start, I explained
more things to her about puzzles and math
and she absolutely loves it.

So, to sum up (and sorry for the long post)
I think an NTP server with a tiny
footprint is just the ticket.

Your comments are most welcome.

Oh, and it would be nice to get
micro-second accuracy.

George, N2FGX

Quoting Tom Van Baak t...@leapsecond.com:


Question: What GPS timing module should I go with? No more Motorola
Oncore so what's best right now? Who sell modules? What are the price
ranges?

Your comments are most welcome.

-George, N2FGX


Hi George,

Welcome back to the list; you've been quiet for a long time. This  
sounds like a great project. I hope you keep us informed with  
progress and also make the results available.


You should be able to find GPS modules with sub-microsecond 1PPS for  
$25. Check sparkfun.com or the Skylab chip used on the  
www.leapsecond.com/pages/MG1613S board. This and other chip  
solutions require SMT/PCB mounting, connectors, external antenna and  
cabling which can add to the net cost of complexity.


A number of people I know who want an inexpensive, turn-key,  
sub-microsecond, embedded GPS timing solution continue to chose the  
Garmin 18x/LVC. These are nice because of the high-gain integrated  
antenna (they work indoors), compact encapsulated design, and  
extreme ease of use (5V, ground, 1PPS).


/tvb



A new LEA6-T single piece cost IIRC 190EUR from the webshop.
A LEA5-T was IIRC half price.

And a little caution: the LEA5 modules use considerably more power during
aquisition than the LEA4 did and the LEA6. IIRC we measured up to 150mA
(compared to 100mA with LEA4). I don't know the Rasberry, but i guess
that should be not a proble, but you should check for it nevertheless.

Attila Kinali


Attila,

I'd say the u-blox 5T or 6T is rather over-kill for George's  
application, both in price and performance (and learning curve and  
integration). Remember that the world of NTP is milli- and  
microseconds. State-of-the-art GPS timing receivers and GPSDO are in  
the nano- and picosecond accuracy/jitter range.


/tvb


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[time-nuts] RasberryPi, timing and GPS receivers

[xaos]

Hello everyone,

I started a new project for myself where I would use the RasperryPi  
Linux board

as a NTP server.

My goal is to design a custom board for the Pi and mount a GPS  
receiver on it. With this combination, I should be able to configure  
NTP for the Pi and thus have the Pi act as a Stratum 1 NTP server.


The new RasberryPI has 512MB memory so it should be fine for running  
just ntpd.


Question: What GPS timing module should I go with? No more Motorola  
Oncore so what's best right now? Who sell modules? What are the price  
ranges?


Your comments are most welcome.

-George, N2FGX


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Re: [time-nuts] RasberryPi, timing and GPS receivers

[xaos]

Michael,

Thank you for your most valuable information.
This is why time-nuts is so amazing!

My goal is actually two-fold.

First, I would like to have a NTP server that I can easily
hook up (well, as easily as possible) without
dedicating a Linux server each time.

My personal use would require 3 separate NTP servers
because I am a time-nut and stratum 2 is not an option.

The idea here is to create a smart piggy-back architecture
where the CPU/Ethernet sits on the bottom
with (perhaps) a few modules on top of that
with GPS right on top (let's call it the penthouse).

For obvious reasons I would put the Power supply
separately.

So we are looking for a very small footprint
NTP server.

Now, I thought the RasberryPi would be ok
even though I did not like the limitations you
mentioned as well. It is very popular.

You mentioned the Olimex olinuxino. Wow!
This is a thing of beauty indeed!

https://www.olimex.com/Products/OLinuXino/A13/A13-OLinuXino/

I really like this board.

My second goal is that if I go to the
trouble of creating a GPS-daughterboard and all that
I'd like to have other people use it as well
and maybe I would make a small batch.

Cost wise this should be in the 10-20 dollar range tops.

I think I will do some research on this board and maybe
order one. It looks very promising.

I wonder if I can replace the crystal with a better
high stability one.

-George

Quoting Michael Tharp g...@partiallystapled.com:


On 10/16/2012 05:06 PM, x...@darksmile.net wrote:

My goal is to design a custom board for the Pi and mount a GPS receiver
on it. With this combination, I should be able to configure NTP for the
Pi and thus have the Pi act as a Stratum 1 NTP server.

The new RasberryPI has 512MB memory so it should be fine for running
just ntpd.

Question: What GPS timing module should I go with? No more Motorola
Oncore so what's best right now? Who sell modules? What are the price
ranges?


It's not a terrible idea, but the RPI has a USB ethernet transceiver  
so in addition to the latency/jitter of the ethernet it also has the  
latency/jitter of the USB. I've also heard of stability problems  
just keeping it running for weeks to months so you should integrate  
some kind of watchdog timer if you can. The actual GPS module  
doesn't matter much since NTP will smooth out even the worst GPS  
jitter. I have heard second-hand (or third-hand or fourth-...) that  
some have a significant persistent delay and that could be more of a  
problem. If you want to go for a timing-oriented receiver you can  
get a used Trimble Resolution T from ebay but they have a 2mm pitch  
header.


You will want to house the RPI and GPS receiver in a box where it  
will not be subject to wide temperature swings, insulated and  
shielded from drafts. It would also be interesting to upgrade the  
main oscillator to a temperature-compensated model so NTP doesn't  
have to work as hard to keep the frequency locked.


Personally I would recommend getting a more robust single-board  
computer, e.g. a PC Engines ALIX or Olimex olinuxino. RPI is cheap  
but hard to source, not open-source, and does not have good  
long-term prospects due to the microprocessor being used. Most of  
the attention is due to deliberate publicity by the manufacturer and  
not novelty or merit. If you must use the cheapest board then by all  
means do so, but just know there is better available for not much  
more.


Happy ticking,
-- m. tharp

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Re: [time-nuts] RasberryPi, timing and GPS receivers

[xaos]

Annoyance with small Linux boards:

My single biggest annoyance is that
all the I/O connectors are coming out from
all 4 directions.

What I mean is this:

It would be nice to have ethernet+LEDs+USB+VGA(HDMI)
come out from one side, and Power/I/O/RS232
from the opposite side.

This way if I make a case I only need
to worry about what is coming out of the
Ethernet side.

The RPI has ethernet+usb on one side and HDMI from another.
How do you make a decent case with only one side open?
It is impossible.

If they only had the HDMI on a header so I can break it out.
Same for audio/USB

-George


Quoting sh...@impsec.net sh...@impsec.net:


Michael Tharp g...@partiallystapled.com wrote


[RE: raspberry pi ntp server]


It's not a terrible idea, but the RPI has a USB ethernet  
transceiver so in addition to the latency/jitter of the ethernet it  
also has the latency/jitter of the USB.
I've been playing with a pair of Raspberry Pi ntp servers, one with  
a $15 Sure Electronics GPS evaluation board, which was very easy to  
interface to (3.3v uart and pps outputs) and the other connected to  
a Lucent RFTG, which once I figured out that the Pi apparenty  
tolerates the PPS out from the RFTG w/o a level shifter just fine  
(mostly - I was getting false extra pulses until I shielded the  
line, which I hadn't needed to do on the Sure GPS board).


I'm a junior time-nut at best but it looks to me like jitter from  
the USB Ethernet is acceptably low, based on ntpq -p anyway:


   remote   refid  st t when poll reach   delay   offset  jitter
==
oGPS_NMEA(0) .GPS.0 l2   16  3770.000 
0.003   0.004
+pi2 .PPS.1 s7   16  3770.945
-0.004   0.044
+pool-test.ntp.o 216.218.192.202  2 u   43   64  377   73.855 
1.382   0.262



   remote   refid  st t when poll reach   delay   offset  jitter
==
oPPS(0)  .PPS.0 l18  3770.000
-0.024   0.061
+ntp .GPS.1 s   148  2520.983 
0.217   0.615
*tick.nullmodem. 128.252.19.1 2 u   60   64  377   35.066 
0.562   4.556



Some of the offset between the two might be that I am waiting for a  
2nd GPS antenna to arrive for the RFTG and it's been undisciplined  
for a few days, it might be from the ethernet jitter, the Sure GPS  
might be off, or it might be from the fact that I may have a  
configuration issue someplace - ntpq -c rl has them at different  
precisions (-19 and -18), even though I think they're the same  
kernel and ntpd compile.
I've also heard of stability problems just keeping it running for  
weeks to months so you should integrate some kind of watchdog timer  
if you can.
I haven't seen the issue yet but I haven't been running more than a  
couple of weeks.  Part of the problem may be quality of power  
supply, I've seen some people reporting issues if the 5v usb power  
in isn't capable of providing enough current and a stable voltage.




You will want to house the RPI and GPS receiver in a box where it  
will not be subject to wide temperature swings,


I haven't been running either of mine in an enclosure, both are  
sitting up in the unheated attic at the moment, typical offsets from  
loopstats seem to be under 2us, but I should graph them.
It would also be interesting to upgrade the main oscillator to a  
temperature-compensated model so NTP doesn't have to work as hard  
to keep the frequency locked.
I am curious if I could replace the 19.2mhz system clock crystal  
with a stable source generated from the 15mhz RFTG output via a  
clockblock, ala what I have seen reported about the Soekris.

Personally I would recommend getting a more robust single-board computer

I don't disagree that the Pi has its flaws but it has been fun to play with.

-shaun


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Re: [time-nuts] RasberryPi, timing and GPS receivers

[xaos]

The miniITX mobos are quite impressive.
There is no argument there.

However, My simple idea was this:

Since I want to keep time at 3 separate locations
and wanted stratum 1 NTP, I didn't want overkill.

Actually my reason for 3 different locations is simple:
Internet is flakey some places and sometimes just down.
I'd like to have correct time no matter what
happens to the internet.

The other thing I want to do is create a very small footprint
NTP server that basically looks like 3-4 cartons of
cigarettes stacked on top of each other.

Maybe even have the power supply on the bottom
of the stack.

I don't know if I'll be able to do this
but this is the general idea.

I think maybe something like this:

GPS Receiver + antenna connector
---
Interface board
---
CPU main board
---
Shield board (mostly ground plane)
---
Power supply
---

If I could put this in a nice aluminum
case I think it would look beautiful.

-G

Quoting Chris Albertson albertson.ch...@gmail.com:


On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote:


One does NOT need a dedicated server for NTP.  NTP can run on a  
linux system

that is also a web and mail server or on e  linux desktop system that you
use for web surfing and web browse ring, just as long as the box stays
running and you don't turn it off.


It's been discussed before, but probably worth repeating.

Don't overlook the cost of power.  If you have an old power-hungry CPU that
you use for mail and web, leaving it on all the time can cost a lot.


Yes.  You are right.  that is why I posted a like to this
http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442
this board uses very little power and as you say will pay for itself
quickly.  You can reast your hand of the heat sink and notice there is
no fan.  It uses just a few watts. and can run VMware, and multiple
servers



The
payoff time for replacing it with a low power system can be as low as a year
or two.


--
These are my opinions.  I hate spam.




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--

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] RasberryPi, timing and GPS receivers

[xaos]

Err... I meant packs of cigarettes
NOT cartons :)

Quoting x...@darksmile.net:


The miniITX mobos are quite impressive.
There is no argument there.

However, My simple idea was this:

Since I want to keep time at 3 separate locations
and wanted stratum 1 NTP, I didn't want overkill.

Actually my reason for 3 different locations is simple:
Internet is flakey some places and sometimes just down.
I'd like to have correct time no matter what
happens to the internet.

The other thing I want to do is create a very small footprint
NTP server that basically looks like 3-4 cartons of
cigarettes stacked on top of each other.

Maybe even have the power supply on the bottom
of the stack.

I don't know if I'll be able to do this
but this is the general idea.

I think maybe something like this:

GPS Receiver + antenna connector
---
Interface board
---
CPU main board
---
Shield board (mostly ground plane)
---
Power supply
---

If I could put this in a nice aluminum
case I think it would look beautiful.

-G

Quoting Chris Albertson albertson.ch...@gmail.com:


On Tue, Oct 16, 2012 at 4:37 PM, Hal Murray hmur...@megapathdsl.net wrote:


One does NOT need a dedicated server for NTP.  NTP can run on a  
linux system

that is also a web and mail server or on e  linux desktop system that you
use for web surfing and web browse ring, just as long as the box stays
running and you don't turn it off.


It's been discussed before, but probably worth repeating.

Don't overlook the cost of power.  If you have an old power-hungry CPU that
you use for mail and web, leaving it on all the time can cost a lot.


Yes.  You are right.  that is why I posted a like to this
http://www.newegg.com/Product/Product.aspx?Item=N82E16813121442
this board uses very little power and as you say will pay for itself
quickly.  You can reast your hand of the heat sink and notice there is
no fan.  It uses just a few watts. and can run VMware, and multiple
servers



The
payoff time for replacing it with a low power system can be as low  
as a year

or two.


--
These are my opinions.  I hate spam.




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--

Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Google NTP Servers and smearing leap seconds...

[xaos]

You can forget Wall St. firms and Banks for starters.

They need sub-microsecond accurate timing as some instruments (Forex)  
are moving to 10 microsecond latency from order entry to order ack.


Although some software (FIXX) needs a lot of work to get there, they  
are moving in that direction.


-George, N2FGX

Quoting shali...@gmail.com:

That would be nice it is were a standard and everybody was doing it,  
because otherwise, for a day, your own network might be happy, but  
if you have any app that needs to communicate with the outside  
world, you are in a lot of hurt.


Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-Original Message-
From: Doug Calvert dfc-l...@douglasfcalvert.net
Sender: time-nuts-boun...@febo.com
Date: Thu, 15 Sep 2011 16:34:39
To: Discussion of precise time and frequency measurementtime-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: [time-nuts] Google NTP Servers and smearing leap seconds...

Time Technology and leaping seconds

http://googleblog.blogspot.com/2011/09/time-technology-and-leaping-seconds.html

The solution we came up with came to be known as the “leap smear.” We
modified our internal NTP servers to gradually add a couple of
milliseconds to every update, varying over a time window before the
moment when the leap second actually happens. This meant that when it
became time to add an extra second at midnight, our clocks had already
taken this into account, by skewing the time over the course of the
day. All of our servers were then able to continue as normal with the
new year, blissfully unaware that a leap second had just occurred. We
plan to use this “leap smear” technique again in the future, when new
leap seconds are announced by the IERS.

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Re: [time-nuts] Google NTP Servers and smearing leap seconds...

[xaos]

You are right.

To be more precise, I should have said that the time sync should be at  
least 1 order of magnitude less. In the case of 10us turnaround time,  
it is assumed that the timesync is 1us. This is the reason that  
everyone uses multiple stratum 1 NTP servers using GPS in their  
datacenters.


So the Forex transaction goes like this:

1. (Both parties) Are we in proper sync timewise?
2. (Party 1) I need transaction type x. My timestamp is: .. Go.
3. (PArty 2) Confirmed. My timestamp is: .. Go.

These timestamps are legal entities and bind both parties to the transaction.
That's why transactions have a data transfer entity in the middle  
(Reuters, Bloomberg) which guarantees proper timesync for all involved.


With Reuters in the middle, only the Reuters timestamp (arrival time  
and send time) can be trusted.


However, Many times you will see a Reuters machine lose sync and the  
UNIX SA's will restart NTP on it. Reuters puts more than one machine  
per site for redundancy.


Quoting Hal Murray hmur...@megapathdsl.net:



x...@darksmile.net said:

You can forget Wall St. firms and Banks for starters.



They need sub-microsecond accurate timing as some instruments (Forex)   are
moving to 10 microsecond latency from order entry to order ack.


10 microsecond latency doesn't say anything about how accurate the time has
to be.

Does anybody have a good URL on the accuracy requirements of banks and/or
stock markets?  I expect there are both legal and technical issues.  I'd like
to understand them separately but I won't be surprised if they are thoroughly
tangled.

--
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] Google NTP Servers and smearing leap seconds...

[xaos]

With the recent wild fluctuations in the Commodities markets it is  
incredibly important that time delay between any 2 parties (in a  
financial transaction) be reduced to a minimum.


Only a few years ago, gold, silver and oil would vary by a few dollars  
(at most), intraday and even intraweek.


Lately, we had jumps of a few hundred dollars in a few minutes/seconds.

If a bank makes a few 100+ Mil transactions a day (trust me this is  
not even a blip on the radar in some places) those extra microsecs add  
up.


Now, one would think mathematically about this and say it should  
average out. Well, no! The market (for some weird reason) has a mind  
of it's own and when you start to lose money, it just gets worse and  
worse.


Even the best mathematical predictors (computer models and humans)  
break down when the market volatility (randomness) goes up.


What does up or down volatility mean? Depends on the day.

The point is, when the proverbial shit hits the fan, you want to bail  
out of your position ASAP. However, the time delay between you and  
your overseas party added another 50-1000 microseconds to the closing  
time, you just lost another  dollars and in a losing day that adds  
up!


I've worked on trading floors for many years and seen people drop dead  
after they got closing confirmation!


No wonder most traders are so young.

Have a nice weekend everyone!

Quoting shali...@gmail.com:

I just read they were building a new transatlantic cable that will  
shave 10uS from the normal 60 or so uS and that for large traders,  
1uS represents 100 million $ per year saving/increased revenue.


Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-Original Message-
From: x...@darksmile.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 16 Sep 2011 13:05:40
To: Discussion of precise time and frequency  
measurementtime-nuts@febo.com; Hal Murrayhmur...@megapathdsl.net

Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...

You are right.

To be more precise, I should have said that the time sync should be at
least 1 order of magnitude less. In the case of 10us turnaround time,
it is assumed that the timesync is 1us. This is the reason that
everyone uses multiple stratum 1 NTP servers using GPS in their
datacenters.

So the Forex transaction goes like this:

1. (Both parties) Are we in proper sync timewise?
2. (Party 1) I need transaction type x. My timestamp is: .. Go.
3. (PArty 2) Confirmed. My timestamp is: .. Go.

These timestamps are legal entities and bind both parties to the transaction.
That's why transactions have a data transfer entity in the middle
(Reuters, Bloomberg) which guarantees proper timesync for all involved.

With Reuters in the middle, only the Reuters timestamp (arrival time
and send time) can be trusted.

However, Many times you will see a Reuters machine lose sync and the
UNIX SA's will restart NTP on it. Reuters puts more than one machine
per site for redundancy.

Quoting Hal Murray hmur...@megapathdsl.net:



x...@darksmile.net said:

You can forget Wall St. firms and Banks for starters.



They need sub-microsecond accurate timing as some instruments (Forex)   are
moving to 10 microsecond latency from order entry to order ack.


10 microsecond latency doesn't say anything about how accurate the time has
to be.

Does anybody have a good URL on the accuracy requirements of banks and/or
stock markets?  I expect there are both legal and technical issues.  
 I'd like
to understand them separately but I won't be surprised if they are  
thoroughly

tangled.

--
These are my opinions, not necessarily my employer's.  I hate spam.




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Re: [time-nuts] Google NTP Servers and smearing leap seconds...

[xaos]

Love it!

You just brought to mind one of the least known (but best) true  
stories about Linux, Windows big money and even bigger BS.


This is an absolutely 100% true story:

September 8, 2008 was the busiest Forex trading day in the history of  
stock markets.


On that day, the London stock exchange failed. It was down for the entire day.
Fortunes were lost.

Why? Well, it is a well known fact that the Exchange (LSE) was run by  
a notorious Windows advocate by the name of Clara Furse. It was her  
push to an All Windows Shop that brought to light some serious  
architectural problems with Windows. Especially when exposed to a  
super high volume trading environment.


Even as the exchange was shut down by Windows issues she continued to  
praise MS and Windows for the great job they did in solving the  
problems.


She lost her job soon after this incident. Good riddance. I had  
dealing with her office (and some of her staff) and they were a bunch  
of idiots.


Linux is now the standard among any Wall St. and Banking firms.  
Nothing compares.


Read this article for more info:  
http://blogs.computerworld.com/14876/london_stock_exchange_dumps_windows_for_linux


Google has a ton of more info on it.

-George

Quoting li...@lazygranch.com:

Bring back the transaction tax and I suspect these timing issues  
will go away.


I recall reading the London exchange was experimenting with linux  
and mysql, supposedly faster than what they were using.


-Original Message-
From: x...@darksmile.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 16 Sep 2011 16:59:01
To: time-nuts@febo.com
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...

With the recent wild fluctuations in the Commodities markets it is
incredibly important that time delay between any 2 parties (in a
financial transaction) be reduced to a minimum.

Only a few years ago, gold, silver and oil would vary by a few dollars
(at most), intraday and even intraweek.

Lately, we had jumps of a few hundred dollars in a few minutes/seconds.

If a bank makes a few 100+ Mil transactions a day (trust me this is
not even a blip on the radar in some places) those extra microsecs add
up.

Now, one would think mathematically about this and say it should
average out. Well, no! The market (for some weird reason) has a mind
of it's own and when you start to lose money, it just gets worse and
worse.

Even the best mathematical predictors (computer models and humans)
break down when the market volatility (randomness) goes up.

What does up or down volatility mean? Depends on the day.

The point is, when the proverbial shit hits the fan, you want to bail
out of your position ASAP. However, the time delay between you and
your overseas party added another 50-1000 microseconds to the closing
time, you just lost another  dollars and in a losing day that adds
up!

I've worked on trading floors for many years and seen people drop dead
after they got closing confirmation!

No wonder most traders are so young.

Have a nice weekend everyone!

Quoting shali...@gmail.com:


I just read they were building a new transatlantic cable that will
shave 10uS from the normal 60 or so uS and that for large traders,
1uS represents 100 million $ per year saving/increased revenue.

Didier KO4BB

Sent from my BlackBerry Wireless thingy while I do other things...

-Original Message-
From: x...@darksmile.net
Sender: time-nuts-boun...@febo.com
Date: Fri, 16 Sep 2011 13:05:40
To: Discussion of precise time and frequency
measurementtime-nuts@febo.com; Hal Murrayhmur...@megapathdsl.net
Reply-To: Discussion of precise time and frequency measurement
time-nuts@febo.com
Subject: Re: [time-nuts] Google NTP Servers and smearing leap seconds...

You are right.

To be more precise, I should have said that the time sync should be at
least 1 order of magnitude less. In the case of 10us turnaround time,
it is assumed that the timesync is 1us. This is the reason that
everyone uses multiple stratum 1 NTP servers using GPS in their
datacenters.

So the Forex transaction goes like this:

1. (Both parties) Are we in proper sync timewise?
2. (Party 1) I need transaction type x. My timestamp is: .. Go.
3. (PArty 2) Confirmed. My timestamp is: .. Go.

These timestamps are legal entities and bind both parties to the  
transaction.

That's why transactions have a data transfer entity in the middle
(Reuters, Bloomberg) which guarantees proper timesync for all involved.

With Reuters in the middle, only the Reuters timestamp (arrival time
and send time) can be trusted.

However, Many times you will see a Reuters machine lose sync and the
UNIX SA's will restart NTP on it. Reuters puts more than one machine
per site for redundancy.

Quoting Hal Murray hmur...@megapathdsl.net:



x...@darksmile.net said:

You can forget Wall St. firms and Banks for starters.


They 

Re: [time-nuts] an interesting problem

[xaos]

I wonder if there is any value to performing a FFT on the data.

-GKH

Quoting jimlux jim...@earthlink.net:


Here's an interesting problem..

I've got a system at work with an internal clock oscillator that I want
to get some statistics on, but there's no direct visibility for the
oscillator, nor do I have a convenient test point that I can probe.

I can divide it down by an arbitrary number to generate pulses which I
then send out via SpaceWire timecodes.  SpaceWire is a fast point to
point digital data link and it has a special capability that
essentially has a tick in signal at one end and a tick out signal
at the other end.  The latency between tick in and tick out is random,
but bounded and discrete.  the link runs at a clock rate derived from
the same oscillator, and you have to wait until the current character
being sent has been clocked out before you can send the special
timecode token.

THat is, I can detect the tick out pulse and it has a random N*[0-14]
clock delay (distributed more towards 0 than 14) from when the tick
in (which is synchronous with the clock I want to measure).  N is the
ratio between my clock and the data rate on the wire ( 7, in this case,
so the time step is about 100ns)

So, by making measurements of the time when the tick out appears (or
time between tick_out pulses) can I somehow take out the random
variability of the link.

It seems, since the clock isn't *terrible* that I could, for instance,
accumulate statistics, and throw out the ones that have more than 0
clock latency (which is probably a few 10s of percent of the ticks.. I
haven't looked yet).  Or, given that the interval between ticks is one
of 28 or 29 discrete values (plus the underlying clock variance), if
the clock variance on a given pulse is clock rate, the
histogram/probability distribution of times would look like a bunch of
little humps, each with variance =clock variance.

or, is a real oscillator going to have an instantaneous variance that
is comparable to or greater than 1 clock pulse?

tvb's site has some sample ADEV numbers, and I would imagine that his
HTV-2 TCXO has comparable performance (at least over the short run at
constant temperature).. He shows ADEV of 1E-9 from 1-1000 seconds...


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Re: [time-nuts] From GPS World - Lightsquared has been given the go ahead

[xaos]

It is not cynicism if it is the truth.

The previous head of the FCC was none other than the son
of Gen. Colin Powell: Michael K. Powell.

The same Powell who allowed Verizon (and other telco's)
to stop sharing their lines and as a result made the
price of DSL skyrocket.

The Powell who pushed for BPL despite the ARRL's data
showing massive interference.

That's just one instance of FCC being in the pocket of
big business.

Not to mention last month's controversy about
net neutrality (where FCC caved in).

So, no cynicism. Just the truth.

George Hrysanthopoulos

Quoting William H. Fite omni...@gmail.com:


Truly impressive level of cynicism...




On Tue, Feb 1, 2011 at 7:38 PM, Chris Albertson
albertson.ch...@gmail.comwrote:


They did exactly the same thing in the past.  It's not the current
administration.  FCC commissioners are appointed to FIVE YEAR TERMS.
Remember the BPL proposals and the way the FCC granted that and that
ARRL had to sue.  The FCC has always voted this way.  BPL was yet
another internet broad band scheme that would have polluted the RF
spectrum.  FCC is predictable on this issue




On Tue, Feb 1, 2011 at 4:22 PM, Don Latham d...@montana.com wrote:
  The FCC is a lackey of the present administration,

--
=
Chris Albertson
Redondo Beach, California

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Re: [time-nuts] Determining Time-Nut infection severity

[xaos]

Only to die and in a split second the mysteries of the universe
will open to you and you will realize that time was relative and
subjective and can be varied by certain jokers.

And, most importantly, your grandfather's grandfather clock
(you know, the one in the living room with the gargoyles)
is really the absolute time standard for all known universes
and when it stops, time really stops but only in the universes
where the gravitational constant is a multiple of 42.

Trust me, I know this. A homeless man from outer space
told me when I came out of CBGB's after watching the Ramones.

Wait, is this the Yahoo urban-folklore group?

73, N2FGX

Quoting Bill Hawkins b...@iaxs.net:


OK, this is an interesting problem, but don't take anything I say
seriously, unless, of course, the shoe fits.

Consider the end stages of TNI. You have acquired everything that
can be acquired. Nothing holds any secrets from you, and so there
are no challenges left. Agreed, some of us will run out of money
or space before we reach that state. The last question may be,
What happens if I compare three hydrogen masers for a full year,
to ascertain the affects of gravity on hydrogen masers?

In almost all cases, your wife (collecting big things is a
testosterone-induced behavior) will be beside herself with worry
about how to recover the money you squandered on your collection
when you die. Her only recourse may be to call a junk collector
and pay to have it all removed, especially the stuff in rented
storage lockers.

The problem of testosterone-induced hoarding behavior (if that
fits) is that basements, rooms, and storage lockers fill up. By
hoarding, you withhold interesting things from beginning time-
nuts -- people who have questions but no equipment with which to
find answers.

If you expect the value of your hoard to increase, consider that
you are subject to the rate of technological change. You'll be
lucky to get 10 cents on the dollar for the bleeding edge stuff
you bought. The nostalgia affect peaks and dies as the old folks
die. On top of that, time is an esoteric field. Put something up
on eBay and you'll be very lucky to get 100 people looking at it.

So do your loved ones (if that fits) and the next generation of
time-nuts a favor and disperse your collection. If it's museum
quality, donate it to a museum (if you can find one that will
take it - you won't be alone). Larry Ware on Jack's Boat Anchor
list would sell stuff at low prices to the guy who wrote the best
story about what he'd do with it.

The problem of dating the tombstone is easily solved. First, you
pick a time to die and work it out with your relatives so that no
one will stop you -- perhaps because you didn't get rid of your
junk. Then you pick a means of death that can be started by an
electrical signal, like a solenoid-driven knife that severs the
thread suspending a sword far above your heart.

Finally, you set up a count-down clock that will provide the
signal. Now you can tell the engraver what to put on your
tombstone. You are relieved of the uncertainty that goes with
not knowing when you will die. Your loved ones can get bank loans
based on what's in your will. It's a win-win situation, as long
as the sword doesn't miss.

Happy Halloween,
Bill Hawkins


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Re: [time-nuts] Determining Time-Nut infection severity

[xaos]

A valid point has been brought up. What does a Time-Nut do with his  
equipment when he dies.


Actually, I am serious here.

My little girl, who just turned four, is already an expert with the  
soldering iron and she can name most components. Actually she is very  
good with microwave components and she can name all the waveguide  
types, magnetrons, attenuators etc, etc..


So, I am lucky I guess (so far). I hope she will grow up to be a  
proper EE like her Dad.


But what if she is not? What am I to do with my equipment if I go to  
the big Atomic Clock in the Sky?


I would definitely not sell it while I was alive! What we need here is  
maybe a Time-Nut Museum. A place where our trusted equipment can go  
and spend their remaining days with other equipment like them.


Otherwise, I just might request to be buried all my stuff. Like in a  
small mausoleum. I am only half joking!


George, N2FGX

P.S. I know I haven't said anything here for a while. Too busy raising  
a little EE and working. 73's to all!


Quoting Daniel Schultz n8...@usa.net:

But what about the other date on the tombstone? You would need to   
work out the

calibration of the clock in the delivery room on your 0th birthday, and hope
that your mother's doctor was also a time nut..


One can only hope that the local coroner is also a Time-Nut, so that time
of death can be determined with suitable accuracy and precision. Does
anybody know how many bits of precision are used on tombstones these
days?



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[time-nuts] We are in Slashdot

[xaos]

This was the story at Slashdot today.

http://hardware.slashdot.org/article.pl?sid=07/12/11/0517234

I bet some of our guys (febo, leapsecond) are seeing an increased  
volume as well.

-George


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[time-nuts] Fury Interface Board simulation results

[xaos]

Hello Everyone,

I have been running simulations of different parts of the Fury Interface 
board.

Here are the results so far.

http://www.darksmile.net/ee/index.html

Your feedback is most welcome.

-George

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Re: [time-nuts] Fury Interface Board: 5MHz needed?

[xaos]

); SAEximRunCond expanded to false
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Hello everyone,

Shall we consider 5MHz OCXO's?

I have a BUNCH of those. Most are really low end devices but I also have 
a few gems.
I mean, some people might have a really nice 5MHz OCXO. Why exclude 
them, if we don't have to?

Anyone out there with interest in this?

If nobody, except me, wants this I'll just drop it.

Bruce suggested that a NIST JFET frequency doubler might do the trick.

What does the math say?

If the frequency is multiplied by two, what else is multiplied?
Frequency error? I would think so.

What about phase noise?

Does the overall error stay the same?

How would that fit with the Fury?

Any thoughts here?

-George

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Re: [time-nuts] Fury Interface Board: How about TI OPA277? -- Very Long Reply

[xaos]

); SAEximRunCond expanded to false
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Hello everyone,

Needless to say, but I have also been following this discussion closely.

First, I must confess, I started this project without making clear
what my requirements were.

Personally, I knew what I wanted. However, when I asked the members of this
list for their feedback, I did not properly explain the details.

My apologies, to everyone here, for any mix-ups.

The idea was this:

What I have is this:

1. A Fury GPSDO.
2. Quite a few HP OCXO's. Some are 10544A's and others are 1081- types.
   Over the years I've collected these from 5328A's or 5370A/B's.
3. I have some Crystek CO27VS12DE-02-10.00, OCXO's.
4. A bunch of different power supplies. Lambda's are really nice.
5. OrCAD Capture/Layout/PSPICE
6. Tools and test equipment.
6. Some free time.

What I'd like to get:

A MTI OCXO. The 230 series types.

What I am trying to do:

1. Experiment with different types of 10MHz OCXO's and find one, with best
   frequency stability and accuracy.

2. Use the Fury to discipline the OCXO and generate a 10 MHz signal.
   I need this to feed all my test equipment.

3. Design a proper system and build a board.

4. The board must handle the different OCXO's I have. It must take the EFC
   signal, from the Fury, and translate it to the EFC input of the 
different OCXO's.
   The translation circuit must handle 0-(+5VDC) input and have the option
   of producing:
  
   [0-5V] or [0-10V] or [-10 - +10V]
  
   This will, not only, handle my current OCXO's but leave room for 
future expansion.
   Between these 3 voltage ranges, I think I have most industry OCXO's 
covered.

4. While I am making a board for myself, make a few more for
   anyone here who would be interested.

5. Have fun.

Why:

My primary, secondary, tertiary and quaternary frequency standards are
the HP Z3801A's. They are not getting any younger. I need something new 
here.

That's it.

As expected, the members of time-nuts have been just great with their 
feedback.

However, the discussion has become heated at times.

This was not a surprise. We are all techies and we do this for a living
and we'll be damned if we give up a point without a fight.

I do not want this to be a deterrent to the discussion. I want to hear
from every person who has something to offer.

If I mean, if anyone is getting beat up here, it's me... right? My 
original design
is pretty much scrapped.

The thing is, I expected this to happen. It happens all the time in the 
real world
and this is how really good systems are made. By consensus.

Anyway, moving on to more technical details...

Over the course of this discussion the following have become clear.

a. The power supply must have 3 outputs and they must be isolated from 
each other.

   +24V for the HP OCXO oven.
   +12V for the OCXO supply
   +/- 12V for other circuits.

b. The +/-12V, for the EFC translation circuit, might need to get +/-15V 
from the
   power supply. If the output is to swing to [-10V] - [+10V] then this
   might be too close to the 12V rails.

   Does anyone know of a quiet voltage regulator for that range?
   If I add more filter caps to fix this, would this be enough? Might be 
bulky.

c. In order to handle the different voltages required, the only option 
is a 24V power supply
   capable of producing + and - 24V.

c. The 3 grounds must be of a star configuration (from the power supply 
ground) to avoid noise.

d. The EFC translation circuit is going to be a challenge. The right 
OPAMP + reference selection
   is extremely critical. I am currently working on the simulation of 
the circuit that Bruce has provided.

   I know what Said is saying about, how much EFC voltage deviation is 
really required.
   However, I don't want to worry about that.

   If I have a Crystek, today, I might have brand-X tomorrow. I don't 
want to play
   games with the OCXO EFC range. I must be able to handle the entire range.

e. The 10MHz output from the OCXO must be connected, via an isolation 
transformer, back to the Fury.
   This will isolate the boards. I am thinking of the Mini-Circuits 
TMO-1-1+ or TMO-1-1T or T1-6-X65.

Questions that I still have:

1. Besides creating a star configuration, for all 3 grounds, what else 
should I do to minimize noise
   and maximize isolation between them?

2. In the case of the HP 10544A an isolation amplifier might be needed 
to connect to the Fury OCXO 10MHz
   input. The other OCXO's can connect to a 5Ohm load. Is this true?
  
   If this is true then shall I just feed the output of all OCXO's 
through the isolation amplifier?
   In other words, shall I also do this for the OCXO's that can handle 
50 Ohm loads?

   I don't think I have an option here. If I add a Mini-Circuits 1:1 
transformer to connect back
   to the Fury, then some sort of isolation amplifier will be needed.

3. Said said, that a thermistor should be placed between the Fury OCXO 
VCC and ground. Since I will be
   breaking 

Re: [time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board

[xaos]

); SAEximRunCond expanded to false
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Said,

In this particular case, I would solder a single header pin, to each  
hole in the OCXO footprint, and then use a single wire header  
connector to attach to it.

Then, have all 4 wires connect to the interface board via a 4 pin, connector.

This way, the Fury gets soldered only once and can be disconnected anytime.

I will add that to the schematic.

Bruce Griffiths, has been providing me with some excellent feedback on  
the EFC interface design. I am making a few changes based on his  
recommendations.

The more I think about it, the more I am worried about ground  
isolation between the HP OCXO and the rest of the system.

I have a few ways to approach this. One is to simply provide 3  
different voltages to the system, each isolated from each other. In  
other words, don't use
voltage regulators to get from +/-24V down to 12.

The proper solution would be for a separate board which provides 3  
different DC outputs, all isolated from each other, including ground.

1. +24V for the oven. HP OCXO's only.
2. +12V For the oven. This could be supplied by the Fury which also  
compensates for temp.
3. +/-12V for the EFC interface.

The interface board must not add noise to the Fury. Looks like there's  
more work to be done.

-G

Quoting [EMAIL PROTECTED]:


 In a message dated 10/30/2007 11:17:58 Pacific Daylight Time,
 [EMAIL PROTECTED] writes:

 Ok,  this one is somewhat difficult. The HP oscillators have +12 and
 +24 V supplies. MTI requires +5 to +15 and Crystek needs +12. So  we
 have a wide range here. What does the Fury  supply?

 A compromise has to be made.

 On the Fury, Is  there a connector that breaks out the pinout of the
 OCXO or  would the individual power pins need to be directly soldered to?

 I  would rather avoid direct soldering. I want to have the Fury is a
 untouched state, if possible.



 Hi George,

 Fury supplies 10.5V nominally at the OCXO's pins next to the SMA  connectors.
 220mA max is expected. Most 12V OCXO's will work well at  10.5V.

 Unfortunately this means soldering to the power pins of the OCXO footprint
 directly, unless you can clamp a wire into the holes.

 bye,
 Said



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Re: [time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board

[xaos]

); SAEximRunCond expanded to false
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Said,


 Hi George,

 nice design!

Thanks :)


 Here are some thoughts from my side:

 The LT1208 has a fairly significant Voffset-versus-temp sensitivity. Maybe  a
 part like the LTC6244HV with about 1/10 the offset drift would work better,
 and reduce the thermal sensitivity of the overall system.

 For example, the LT1208 has 25uV per Degree C drift, and with a standard  MTI
 OCXO which has about 40Hz deviation from 0V to 5V EFC this would be about
 2E-011 drift per degree Celsius worst case just due to the opamp   
 drift, a fairly
  significant amount.

 The LTC6244HV part only allows a power supply range of +-5V so you may  want
 to add low-noise 5V and -5V regulators for the opamps.

Those are some very good points.

What I need then is a device with a +/-12V supply, with better specs  
than the LT1208. Otherwise I can't get the output to swing +/-10V.

+/-10V is what some commercial OCXO's require for EFC. I would like to  
have this flexibility.

I picked the LT1208 because I used it in the past and it will give me  
the output voltage range.

Any ideas here are most welcome. Dual device packaging is not  
important. The right device is.

My simulation, in PSPICE, was only the first step to check on the  
design. In reality, as we all know, things are very different.

This design is far from being cast in stone.



 The feedback and reference resistors R1, R2, R5, R6 are fairly high  value,
 and thus will add noise to the EFC. Make sure to use metal film   
 types  here. To
 reduce overall noise, you may want to add a simple RC lowpass filter to  the
 output of the opamp, say four X7R 22uF10V caps driven by a 4.7K  metal film
 resistor etc.

Values for R1,R2,R5 and R6 are not really important. It is the ratio  
that matters. So 1% metal film resistors of say, 100, 200 and 400 ohms  
should do fine. I'll check the simulation for current bias points but  
it should be minimal.

The output RC lowpass filter is a very good idea. I'll definitely  
build that in.


 Ground loop current coming from the OCXO heater through the OCXO ground pin
 and the ground plane can also cause some EFC error. Make sure to route the
 OCXO ground to the OCXO ground pin on the Fury, and then separate-out the EFC
 ground through a star-type layout. The idea is to prevent the OCXO heater
 ground  current from flowing through the EFC circuitry and SMA   
 cable, in which it
 would  cause voltage drop and thus thermal sensitivity.

Ok, this needs to be done. No question. I will separate the grounds. I  
will go even further and isolate the ground of the OCXO heater from  
everything else.


 Also, you may want to allow the OCXO to be powered from the Fury OCXO
 footprints' power pins. The Fury can compensate for thermal   
 sensitivity if this  is
 done. Alternatively, a thermistor may be connected to the OCXO, and driven by
 the Fury's OCXO power pins (thermistor must handle 10.5V!). As long as the
 current varies with temperature on the OCXO power pins, the Fury will learn,
 and  compensate thermal sensitivities in the system. BTW: the thermal tempco
 measurement is disabled via software command by default on the SMA   
 Fury's, and
 can be enabled via SCPI command.

Ok, this one is somewhat difficult. The HP oscillators have +12 and  
+24 V supplies. MTI requires +5 to +15 and Crystek needs +12. So we  
have a wide range here. What does the Fury supply?

A compromise has to be made.

On the Fury, Is there a connector that breaks out the pinout of the  
OCXO or would the individual power pins need to be directly soldered to?

I would rather avoid direct soldering. I want to have the Fury is a  
untouched state, if possible.


 Hope this helps,
 bye,
 Said

This type of feedback is exactly what I need!

-George



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Re: [time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board

[xaos]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Bruce,


 If this board is intended to power an HP10544A some provision for the LC
 power supply filter required by this oscillator should be made to avoid
 adding large oven switching frequency related spurs to the oscillator
 output.

You are absolutely right that the filter should be there.

I will add that to the design.

-George


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[time-nuts] Pre-Release Docs and Schematics for the Fury Interface Board

[xaos]

); SAEximRunCond expanded to false
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Hello everyone,

The Fury Interface board is closer to reality!

I think I have included everything in there. At least the things that  
I would like to have. However, I am sure that the members of time-nuts  
will add many suggestions.

The pre-release documentation can be downloaded here at:

http://www.gs3tech.com/

Look for the documentation link, in the News Section, on the bottom of  
the page.

Please keep in mind that this is, very, preliminary information. There  
will probably be errors and omissions.

Once the schematic is done, then I'll finish the layout. Maybe I can  
send the files to the board house by next Monday.

At this point we are only planning to manufacture the board itself. We  
do not foresee building a populated and assembled board. Perhaps a kit?

However, this might change if the interest is there.

This should also keep the costs down.

Regards,

George Hrysanthopoulos, N2FGX


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[time-nuts] EFC Input pin impedance for the HP 10544A and 10811-6011

[xaos]

); SAEximRunCond expanded to false
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Hello everyone,

Does anyone know the input resistance of the EFC pin for the
HP  10544A and 10811-6011 OCXO's?

I have the spec sheet but it is not listed.

Can I assume something like 50K? This the the value for Crystek devices.

-George

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[time-nuts] Fury interface board.

[xaos]

); SAEximRunCond expanded to false
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Hello everyone,

I was hacking away at the Fury and I decided that I needed an  
interface board to go along with it.

So, I fired up my capture/layout program and so far this is what I have:

First, the Fury board will attach to the interface board via 2 SMA connectors.

The interface board will have holes to accommodate connectors for the  
HP 10544A, 10811A/B and 10811A-6011 OCXO. Including the 2 mounting  
screws.

I also have this OCXO:

http://www.crystekcrystals.com/crystal/spec-sheets/ocxo/CO27VS12DE-02-10_000.pdf

So I would have the holes there for this device as well.

I also need BNC connectors for the 10MHz sine wave and 1PPS.

The board would need 24VDC and have regulators for 12V. 24VDC is  
needed by the HP oscillators.

I'd like to see if the members of time-nuts would be interested in  
such a board.

If so, I would make a production run for them. Standard 4 layer RoHS.  
It would be 6-8 weeks until delivery.

Any suggestions are very much welcome.

-George


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Re: [time-nuts] Fury GPSDO orders

[xaos]

); SAEximRunCond expanded to false
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Said,

Can you please send me the Paypal info as well?

-George

Quoting [EMAIL PROTECTED]:

 ); SAEximRunCond expanded to false
 Errors-To: [EMAIL PROTECTED] RETRY

 Hello guys,

 we are ready to start shipping the Fury units out to you. We have sent
 PayPal payment information to the following members, please let me know if I
 missed anyone:

   Don
 Renso
 Jerry
 Tom
 Matt
 Ernie
 Scott
 Matt
 Brian

 Please let me know if you wanted a unit and did not receive the PayPal
 request yet.

 Thanks again,
 Said




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Re: [time-nuts] Bush Accepts Pentagon Position on GPS

[xaos]

); SAEximRunCond expanded to false
Errors-To: [EMAIL PROTECTED] RETRY

Imagine that, an accurate story from foxnews.

Didn't even have the obligatory jab at the Democrats.

-G

  Quoting James R. Gorr [EMAIL PROTECTED]:

 ); SAEximRunCond expanded to false
 Errors-To: [EMAIL PROTECTED] RETRY


 Not a technical link, just FYI:


 WASHINGTON —  President Bush on Tuesday accepted the
 Pentagon's decision to stop buying Global Positioning
 System satellites that can intentionally degrade the
 accuracy of civil signals used for a myriad of
 purposes _ from tracking aircraft to finding missing
 skiers.

 http://www.foxnews.com/wires/2007Sep18/0,4670,BushGlobalPositioning,00.html


 
 
 Luggage? GPS? Comic books?
 Check out fitting gifts for grads at Yahoo! Search
 http://search.yahoo.com/search?fr=oni_on_mailp=graduation+giftscs=bz

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Re: [time-nuts] Thunderbolt list

[xaos]

Count me in for two units please.

George Hrysanthopoulos, N2FGX
 
 I would also be interested in one.
 
 Thanks
 Don Mimlitch
 
  
 -
 Need Mail bonding?
 Go to the Yahoo! Mail QA for great tips from Yahoo! Answers users.
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[time-nuts] Another GPS Distribution Amplifier on eBay

[xaos]

Here is another  8 port item on eBay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=230088874313fromMakeTrack=true

It looks like Tucker is really cleaning out their inventory on this item.

I know John picked up one and I got another as well.

They are very nice units and you can't beat the price.

-George Hrysanthopoulos, N2FGX

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Re: [time-nuts] HP Z3801A on eBay -- And check this out as well

[xaos]

These boxes used to go for 300-400 and they are definitely worth that.
I will bid on it just in case...


Now, I also like item: 230079813050


  Agilent HP 58517A GPS L1 Distribution Amplifier


I have two of these babies and I can always use another one.

Last time, I picked up one for 130.00. Definitely a bargain.

-George

Jason Rabel wrote:
 I'm not even going to attempt to bid, I bet this thing will go for way more
 than it is worth. (What is it worth anyways?)

 When was the last time one of these (complete) units popped up on eBay?

 Jason

   
 This HP Z3801A GPS Frequency Receiver Oscillator 58503 HAM, item 
 150083329300, is over $200 with 9 days to go.
 It's going to be a long ride.
 Just in case anyone was interested in joining the fray.

 Didier KO4BB
 


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[time-nuts] GPS unit for car navigation -OT ??

[xaos]

Hello everyone,

I have, until now, resisted the urge to buy a GPS navigation system for 
my car.
However, I now have to do some traveling and new and unknown addresses
keep popping up.

There are several different GPS units on the market and they all look OK 
(i guess).

I just want to know which units do the members here consider to be the 
best for
this sort of thing?

Many thanks in advance,

-George Hrysanthopoulos, N2FGX

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Re: [time-nuts] Progress of my HP Z3801A -- Ooops!

[xaos]

First,

Ah, much better. After batteling the perl package hell (i.e. finding the
exact right Debian package that will make it tick) I now have it
running, but
now I need to figure out how to make it tick on automatic. I also
commented out
the cd /opt/ntp/timelord/shm || exit line from the G1 script. How that
one
should be set was non-obvious.

This is the kind of omission that is hard to spot. Actually that
directory is my source code gen home. I have added a separate comment
there to clarify this.

Now, to the more problematic issue of time delay between
:SYST:STAT? invocation and receiver response.

I just wish that the information in the :SYSTEM:STATUS?
command was available separately.

That said, it usually takes 4-5 seconds for the receiver
to respond to this command. As a result, the interactive
interface is sluggish and the auto mode lags behind.

What to do?

1.  Send the :SYSTEM:STATUS? command and report it as-is.
Problems:
Time lag is very obvious but we at least get
what the receiver's state is.

2.  Send the :SYST:TIME? and at least get the time.
Problems:
Ok, we got the info but now we need to send the
:SYSTEM:STATUS? anyway. Then for display purposes
we interpolate the receiver time forward.
Not a bad solution but still...

3. Option of how the user might want this handled.

I am open to suggestions here.

-GH
 
 From: John Ackermann N8UR [EMAIL PROTECTED]
 Subject: Re: [time-nuts] Progress of my HP Z3801A -- Ooops!
 Date: Wed, 30 Aug 2006 16:30:54 -0400
 Message-ID: [EMAIL PROTECTED]
 
  Magnus Danielson wrote:
  
   Yes, there is a time-difference between the reported and the time of the
   machine. The machine has NTP from 4 known good public Stratum 1 NTP 
   servers.
   the 11-13 s time-difference is interesting.
  
  Might your Z3801A be set to GPS time rather than UTC?  That would 
  account for (I think) 13 seconds (or is it 14 now that we've had a 
  leapsecond?).
 
 That's it! Infact, it is apparent if one looks on the webpage:
 
 Receiver Time: 2006-08-30T20:26:30.0 GPS
 Local Time: 2006-08-30T22:26:19
 
 Local Time is UTC + 2h, so there you have 2006-08-30T20:26:19 actually, and
 infact this shows that ISO2 isn't following the ISO format.
 
 Now, with 14 seconds of GPS/UTC offset the receiver Time should be
 2006-08-T20:26:16 and the remaining difference of 3 seconds is maybe due to
 the report-time???
 
 I think it is much better to do the :SYST:TIME? to get the time, while all the
 other stuff very well may come out of the :SYST:STAT? report and parsing.
 
 Ideally it should read out the UTC-GPS time-difference and compensate with 
 that
 OR set it to UTC. Yes, I know I can add commands to the end of my conf-file.
 UTC is better, since then it would handle leap-seconds +/- too early leap-
 second announcements and the leap-second bug.
 
 Cheers,
 Magnus
 
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Re: [time-nuts] Progress of my HP Z3801A -- Ooops!

[xaos]

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Re: [time-nuts] Progress of my HP Z3801A -- Ooops!

[xaos]

Mangus,
 
  Now, to the more problematic issue of time delay between
  :SYST:STAT? invocation and receiver response.
  
  I just wish that the information in the :SYSTEM:STATUS?
  command was available separately.
 
 Much of it is. I have reverse-engineered the actual SCPI command structure, 
 but
 I haven't had time to test them all. Besides, I actually found an error in my
 analysis and haven't had time to fix it.

I can't imagine that the engineers, who designed the system, did not
have a way of getting all the info via another method.

 
  That said, it usually takes 4-5 seconds for the receiver
  to respond to this command. As a result, the interactive
  interface is sluggish and the auto mode lags behind.
  
  What to do?
  
  1.  Send the :SYSTEM:STATUS? command and report it as-is.
  Problems:
  Time lag is very obvious but we at least get
  what the receiver's state is.
  
  2.  Send the :SYST:TIME? and at least get the time.
  Problems:
  Ok, we got the info but now we need to send the
  :SYSTEM:STATUS? anyway. Then for display purposes
  we interpolate the receiver time forward.
  Not a bad solution but still...
  
  3. Option of how the user might want this handled.
  
  I am open to suggestions here.
 
 First of all, not all info needs to be sharp on the microsecond so to speak.
 The EFC, TI and time we would like fairly timely, where as the satellite data
 doesn't need to be that timely, but we like it in snapshot form if possible.
 
 Second, you can experiment with other baud-rates.

I'll try approach 2 on a test version and see how it looks.
 
 Third, there is a Forth interprenter in there, maybe that may put into use to
 create a less verbose format but in a more timely maner? I haven't toyed with
 it yeat, but I think I know how to kick-start it. ;O)

Hmmm... Embedded Forth. It was quite the rage a while back. These days,
it is much easier to just create an embedded Linux image. Hardware is
cheap.
 
 Thanks to the logging, I now see that my Z3801A has an erruption right now.
 I would have enjoyed a TI plot aswell actually.
 
 Cheers,
 Magnus
 

I think that the  GD::Graph perl module only supports two different
scales on the same graph.

What could be done here is combine the TI graph with EFC or HU but
not both. Also the TI graph could be completely separate.

I suppose I could just gen it and leave it to the user on how to display
it.

Comments?

-GH

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Re: [time-nuts] Progress of my HP Z3801A -- Ooops!

[xaos]

Magnus,

Arghhh... I forgot to include it in the build script.

It is there now as version 2.0.3. I double-checked and the file is 
definitely there!

http://www.gs3tech.com/Software_Download.html

-GH

Magnus Danielson wrote:
 Oh... eh... George?

 README:18:  gpschart is included in this distribution.

 Eh... where? I sure would like to run it, but it seems to be missing in the
 tgz:s.

 Cheers,
 Magnus

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Re: [time-nuts] Progress of my HP Z3801A

[xaos]

Magnus,

I have written a Linux based control and graph
application for the HPZ3801A. The software also
controls Motorola GPS Receivers.

It is curses based and also generates graphs
of Holdover Uncertainty and EFC (TI values are also stored).

For some graphs of my two Z3801A's look here:

http://www.darksmile.net/darkgps/index.shtml

You can get the software from here:

http://www.gs3tech.com/

under software download.

-GH
 
 Fellow Time-nuts,
 
 I've left my HP Z3801A unattended but running for quite some time. It now 
 seems
 to have started making more sense. When I checked it a few days ago, it was
 still a bit high in Predicted holdover uncertainty, but right now it clocks in
 at 900 ns/initial 24 hrs. That's about 1E-11 in frequency error. Pretty
 impressive. Now, this is only one sample, so I expect it to be worse for
 awhile (while it dropped to 800 ns). Ah well. Let's see if it sticks. If so,
 I may have a good unit after all, or maybe it is just a better environment for
 it now, who knows.
 
 I am wondering whatever fun I could make of the builtin forth-interprenter, 
 but
 right now I am considering writing myself a logging application (this is not
 the time to again give me tons of links to Windows-apps - no use!).
 
 For the clock-status I'm considering logging the TI-difference and holdover
 uncertainty.
 
 For GPS status I'm considering logging the tracked signal-strengths at their
 different Azimuth and Elevation values. The actual satelite tracks themselfs
 isn't as interesting as their position in the sky relative to my antenna and
 what the signal strength map I get from that.
 
 Cheers,
 Magnus

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Re: [time-nuts] Progress of my HP Z3801A

[xaos]

Joe,

Thank you for the kind words :)

Actually, there is a new version there (2.0.2 as of a few minutes ago)
that fixes a few spelling errors.

-GH
 
 I just took a look at your software. You are to be commended on your clear 
 and detailed documentation. Most GPL software documentation seems to be a 
 few cryptic lines that assume you don't need the documentation anyhow.
 
  You can get the software from here:
 
  http://www.gs3tech.com/
 
  under software download.
 
  -GH
 
 
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Re: [time-nuts] GPS Distribution amplifier

[xaos]

A 50nF Cap should do just fine.
Little smaller/bigger probably ok as well.

Size? A small ceramic should be fine.
After all we are not expecting KW.

Hmmm... I wonder what the power output of a GPS sat is?
Is that classified? Even if it is, if I know it's height
I can probably figure it out. Estimate at least.

Sorry, just thinking out loud.

-GH

Rasputin Novgorod wrote:
 --- xaos [EMAIL PROTECTED] wrote:

   
 8-way splitters  
 Make sure it passes DC. Your antenna will need it.
 Pass the DC from one port and block it from all others.
 

 What size, type block?
 /b

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[time-nuts] HP 3325B Function Generator and GPS based frequency control

[xaos]

Hello everyone,

I found this HP3325B Function Generator on eBay:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItemitem=270006696082

It has the high voltage option but not the High Stability Oven.

Since I plan to use an external GPS based frequency source,
does it matter?

I suspect the unit still has a decent ovenized crystal to begin with.

Any thoughts from the group?

-George Hrysanthopoulos, N2FGX

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[time-nuts] New Version of darkgps software

[xaos]

Hello everyone,

I have released Version 2.0 of Darkgps, the GPS receiver
control software.

DarkGPS consists of a Linux based, open source, software suite that allows
you to fully control your GPS receiver. The software supports
all 6, 8 and 12 channel Motorola GPS receivers and the
HP Z3801A, GPS based, frequency reference source.

Included in the software is:

gpsdisplay - to control the GPS receiver, display receiver data and 
generate data
of receiver parameters, including HTML output.
gpschart   - to create graphs of HP receiver parameters.
ntpscon- which can be used to share GPS receiver data over the net.
Utilities  - to perform administrative functions.

You can download the software from the download section
on the GS3 Technologies Web Site: http://www.gs3tech.com/

To see a few of the capabilities of the software, go to the
darksmile.net web site:

http://www.darksmile.net/darkgps/index.shtml

Regards,

George Hrysanthopoulos

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Re: [time-nuts] Motorola Oncore Basic Command @@Bk Help

[xaos]

Hello Randy,

Your web site is a gold mine of Motorola GPS Receiver info.
I hope to incorporate all the Motorola commands into my program.

Regards,

-George

Randy Warner wrote:
 Xaos/George,

 You can download the entire VP (6 and 8 channel) command reference on
 our website.

 1. Go to www.synergy-gps.com
 2. Go to Technical Support Page and fill in the survey
 3. Go to Shop Talk
 4. On the Shop Talk page scroll all the way to the bottom and download
 the VP Command Reference.

 I made this several years ago by scanning in Chapter 6 from the Motorola
 manual, running it
 Through OCR, and then reformatting it. I also added some extra
 information to explain a
 Little more about how each command works aqs the Motorola version was
 sorely lacking.

 Hope this helps,

 Randy Warner
 Senior Applications Engineer
 Synergy Systems, LLC 

 -Original Message-
 From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On
 Behalf Of xaos
 Sent: Friday, April 28, 2006 5:40 PM
 To: Discussion of precise time and frequency measurement
 Subject: [time-nuts] Motorola Oncore Basic Command @@Bk Help

 Hello Everybody,

 Does anyone here know what the Motorola Oncore @@Bk
 command does? It is from a Basic 6 channel Model.
 More importantly does anyone have the docs for it?

 Many hanks in advance,

 -George, N2FGX

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[time-nuts] Motorola Oncore Basic Command @@Bk Help -- Update

[xaos]

Thanks Brooke and SJ for the quick  response.

SJ: Unfortunately, I can't use the WinOncore12 program as it runs on
Windows. Recently I shut down my last Windows box and
I am running all Linux.

The problem is that I was using TACC32 Software from CNS Systems
to control my Motorola Receivers and the GPSCon software to control
my HPZ3801A Boxes.

When I tried running these programs using Wine(the Linux Windows emulator)
I had no luck.

So I decided to do a re-write of my older software: darkgps to support 
the M12
and the HP stuff. Not a simple task since the Windows programs
are very sophisticated and I want the extra features.

Stuff like plots of receiver parameters, EFC voltages(for the HP units) etc.
are really nice to have. So now,  find myself in the middle of a rather
large software project.

I have access to a 12 channel M12 a few UT units and a few Basic units.
The Basic unit was sending out the Bk command and I did not know how
to process it.

BTW, if anyone here wants to try out the beta please let me know.
There are two programs, a c code shared memory connector
and a perl program that does everything else.

Full source included. I tried to write this one as cleanly as possible 
with plenty
of comments.

Regards,

George Hrysanthopoulos, N2FGX

Brooke Clarke wrote:
 Hi George:

 My 8 channel manual lists it:
 Position/Status/Data Extension Message

 @@BkmCCRLF
 m - mode (0 = respone once when polled, 1.. 255 # per second)
 C = checksum

 @@BkggpphhvvttmmnneeuuaarrCCRLF
 gg- Current GDOP
 pp - Current PDOP
 hh- Current HDOP
 vv - Current VDOP
 tt - Current TDOP

 Velocity :
 nn- North
 ee- East
 uu- Up

 Age of differential correction data
 aa - seconds

 REceiver position in ECEF (X,Y,Z) cm
  -
  -
 -

 URA for each of 6 channels
 r - (0 to 15, 63 not decoded yet)

 least squares A-1 matrix
 ii-

 receiver clock bias
 cc - meters
 osc offset
 oo- m/sec
 C - Checksum

 Have Fun,

 Brooke Clarke, N6GCE

   


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[time-nuts] Motorola Oncore Basic Command @@Bk Help

[xaos]

Hello Everybody,

Does anyone here know what the Motorola Oncore @@Bk
command does? It is from a Basic 6 channel Model.
More importantly does anyone have the docs for it?

Many hanks in advance,

-George, N2FGX

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[time-nuts] Single Board Computer for PIC/Timing experimenters

[xaos]

Hello everyone,

My company, GS3 Technologies Inc., is running
a promotion for a PIC based, Single Board Computer
Development System.

Anyone who registers (only email address required)
at our website:

http://www.gs3tech.com/

will be eligible to win. The drawing will be on March 1st.

The Development System comes complete with a motherboard,
separate prototyping board, and networking software.

The software is a complete implementation of: TCP/IP, ICMP,
DHCP, Telnet, HTTP and most importantly (to the members here), NTP.

The motherboard also has features specific to timing
which I'm sure will be appreciated here.

The complete source code for everything is also included!

The winner will get all this and we'll even pay for shipping.

A similar system will also be given away at the Dayton Hamvention,
by TAPR.

In the future, we will be introducing other time/frequency specific
products such as: IRIG-B Boards, GPS Disciplined Signal Generators,
Distribution Amplifiers, Frequency measurement systems, etc.

Thank you to all the members and especially John for allowing me to post
this.

George Hrysanthopoulos, N2FGX
GS3 Technologies, Inc.

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Re: [time-nuts] Timing receivers' observations of leap second

[xaos]

My two HP Z3801As are still showing Leap Second pending.
My two Motorola Oncores changed right away.

My Trutime Irig-B GPS synchronized generator did something cool.
It did not switch right away but it showed that it was in special mode
and it made the correction about 10 seconds later.

NTP has finally adjusted.

-George
 James Maynard wrote:

Here in Salem, Oregon, USA, I observed two timing displays at the moment 
of the leap second: the display of an Ultralink Model 333 WWVB Decoder 
and that of some PC software from CNS Systems, Inc. I was also listening 
   to the audio of the HF time and frequency stations, WWV and WWVH, at 
that time.

Ultralink Model 333:

My UltraLink model 333 WWVB receiver has not yet recorded the leap 
second, probably because its antenna is in too noisy a location to 
receive WWVB's 60 kHz signal at this time of day. The display still 
indicates that a leap second is pending, and it still indicates an 
offset from UTC to UT1 of -0.6 s.

Apparently the Model 333 WWVB receiver's software does not apply the 
leap second to its display at the scheduled time, althouth it does know 
that a leap second is pending.  It seems that this software does not 
apply the leap second until it actually receives a signal from WWVB with 
the newly adjusted UTC timescale.

The SynTac32 software (from CNS Systems, Inc.) that displays the output 
of my Motorola M12+ timing receiver waited a couple of seconds after the 
leap second occurred before displaying the correct time, including the 
leap second adjustment.

My guess is that this display software, like that in the WWVB receiver, 
does not apply the leap second adjustment at the scheduled time, but 
waits until it receives messages from the M12+ that reflect the newly 
adjusted UTC time scale.

The Motorola M12+ itself, however, as indicated in the posting from 
Christopher Hover [EMAIL PROTECTED], does apply the leap second at the 
scheduled time.

  



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Re: [time-nuts] Timing receivers' observations of leap second

[xaos]

I am looking at the Gpscon software display.
Hal Murray wrote:

My two HP Z3801As are still showing Leap Second pending.



Are you talking about the raw data from the Z3801A or the output of NTP 
servers they are connected to?

My Z3801A turned off the leap bit as expected.

53735 86253.039 127.127.26.3 T22005123123573430+003A
53735 86317.040 127.127.26.3 T22005123123583830+003F
53735 86380.039 127.127.26.3 T22005123123594130+003A
53736 44.041 127.127.26.3 T2200601014532C
53736 109.035 127.127.26.3 T220060101000150329
53736 175.040 127.127.26.3 T220060101000256330
53736 239.041 127.127.26.3 T220060101000400327
53736 302.040 127.127.26.3 T22006010100050332B
53736 365.039 127.127.26.3 T22006010100060632F
53736 431.039 127.127.26.3 T22006010100071232D


  



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Re: [time-nuts] Question concerning failure and value of HP 5371A

[xaos]

You might have a bad battery in there.
Sometimes these things save the configuration in
battery backup-ed RAM.

-George

 
 Hello everybody, 
 my name is Arnold, located in southern Germany, and I am quite new 
 joining this very interesting group - I got as well the fever of precise 
 timing, 
 reading all you comments lot of months back - and learning a lot from all 
 your knowledge and experiences. 
 
 I am collecting already some nice counters and oscillators, OCXOs and 
 Rb-types. My target is to build a very stable and precise frequency standard 
 applying gps.
 
 Now I have the possibility to get (perhaps) a time interval counter 
 hp 5371A in very nice condition, but with a small black point:
 When switching on it indicates:
   Instrument setup lost, Reset to default, Saved Configurations lost. 
 Press any key to continue.
 Is that a severe problem? 
 Is such equipment a 'must' for serious working?
 What is about the value for such a device, more than 600, 1000 ore 
 more $ ?
 
 Thank you at the moment in advance, 
 I am sure that I will have to ask you in future more questions, if 
 allowed.
 
 Best regards from the Lake Constance,
 
 Arnold, DK2WT
 
 
 
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Re: [time-nuts] Distribution Amp

[xaos]

This unit might be 75Ohms.

George, N2FGX

Mike Feher wrote:


This is for general information in case someone else needs an inexpensive
distribution amplifier for a frequency source. Just yesterday I received the
following distribution amp that I purchased on ebay -
http://tinyurl.com/bqalz . So far I have only completed some minimal
testing, as I am in the process of moving my lab but satisfied myself that
this would really do the job nicely. As you can see on the ebay ad it is
made for HDTV. It has 3 inputs and each input has six outputs. The inputs
can be DC or AC coupled. The testing I performed was at 10 MHz. I fed it
with one of my rubidiums with about a 7.8 dBm signal. The output on each of
the six output channels was about 7.3 dBm. This was the same regardless of
the input used or the output measured or of any loading on the other
outputs. It will be ideal to drive a bunch of test equipment simultaneously
from the same source. I did not yet measure any input to output phase shift
or output to output phase difference. Besides, as long as it is constant I
do not care. The outputs are also not isolated, but for what I want it for
that is OK as well. I intend to put an amplifier and a splitter on the
rubidium so I can drive all three ports at once giving me 18 frequency
correlated outputs. I am very pleased with the purchase. It is also small,
another benefit. I did not see any increase in the noise floor as compared
to the rubidium, nor did I see any extraneous spurious. The output, except
for the minimal signal loss was essentially identical to the input. 73 -
Mike 




Mike B. Feher, N4FS
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960






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[time-nuts] PID Loop question as it relates to NTP

[xaos]

Hello Everyone,

I am in the midst of a design for a
new custom CPU board. I decided
to include NTP, in the board software,
for time keeping purposes.

The system is working rather well and
I am able to get millisecond time sync.
BTW this is as good as I'll get
on this hardware.

The background is this:

   I am using a PID Control loop to discipline
   the time and I am wondering if my algorithm
   is the correct one.

   This is what I do:

   Get NTP time every T seconds
   Calculate error
   Calculate correction
   Apply correction slowly.

   This means that if the correction is: C
   and if my smallest system clock increment is: I
   and if there are N clock increments until
   the next NTP get time.

   Then I apply a correction of: C/N for every I.

   In other words, the correction is smooth
   over the NTP sync interval (T).

   This method works quite well and the system
   reaches 100ms sync at almost (10T).

   It reaches 10ms at almost (20T)

And this is my question:

Should I be correcting the system this way
or should I be correcting all at once at the
time of NTP sync.

Should I expect a better convergence
if I use the all at once method?

Your thoughts on this are much
appreciated.

George Hrysanthopoulos, N2FGX


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[time-nuts] 5370A/B Problems

[xaos]

Hello everyone,

This is my first posting to Time-Nuts so please bear
with me if I don't have the proper etiquette.

I guessed that many members here have the
HP5370A(B) counters.

I have 1 5370A and 2 5370B.

For some weird set of circumstances,
all three units failed withing 1 week.

The problem in the 5370A turned out to be
contact problems in the Power up relay.
After much cleaning I was able to get the
unit back up and running.

The 5370B's were much worse off.
It seems that they both suffer from failures
in the U24,25,26 chips on the Arming board.

Unfortunately, the two units are not identical
and I cannot cannibalize one to fix the other.

What I can do is use some chips from the 5370A
to fix the older model 5370B.

So(at last) my question is:

Should I do this?

I am very hesitant about breaking a perfectly
good 5370A which has seen much good service.

BTW, I can't find replacement chips anywhere
on the net.

Many thanks,

George Hrysanthopoulos, N2FGX


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