[time-nuts] Re: Brooks Shera GPSDO

[Arnold Tibus]

Very interesting to read about this good old design!

I have still a board for the Brooks Shera GPSDO and I would like to
complete it, but I cannot find the described 24 MHz/ 6 MHz Oscillator.
So I have some questions to it.

Is it neccessary that these frequencies are exact and running synchronous?
Are there special tcxo available which would fit?
Could I run this board as well with other (e.g. higher) frequencies and
of independent oscillators?
Are there improvements in meantime?

regards,

Arnold, DK2WT


Am 20.02.2022 um 03:11 schrieb glen english LIST:

Larry, Take a look at Brooks Shera's article in QST. you might know of it.

In my opinion, this has been the 'best ever' description of rolling your
own.

The July, 1998 issueBrooks Shera, W5OJM, titled, "A GPS-Based Frequency
Standard. "

https://www.qsl.net/n9zia/wireless/QST_GPS.pdf

I build several of these and they made "good" GPSDOs

much has been written about this, and emulating it for other hardware.

https://k6jca.blogspot.com/2018/12/simulating-brooks-shera-w5ojm-gpsdo.html

https://github.com/k6jca/Brooks-Shera-GPSDO

u can still buy the original PCB PCB

http://www.a-aengineering.com/gps.htm


On 20/02/2022 10:59 am, Larry Gadallah wrote:

After poring over the several valuable references people have posted
here, it seems that even the common commercial GPSDOs have
implementation problems, so it seems like there's no (financially
viable) off the shelf solution.

It would indeed be convenient to have a kit option, but I'd image the
potential marked for a GPSDO kit is vanishingly small.

FWIW, I started with a VE2ZAZ board and an Isotemp OCXO and a Motorola
receiver of questionable provenance. Since then I've gathered an HP
10811D and I have an HP E1938A coming (I think), so I have only so far
gathered some essential components that I hope are competent.

On Sat, 19 Feb 2022 at 07:13, Bob kb8tq  wrote:

Hi

Building a kit is very different than a from scratch design. A
Heathkit (to extend the years ago ham radio analogy) radio
was an option when you shopped for your Drake. Building it
would give you some experience.

The Heathkit *design* was done for you and all the complicated
higher level stuff was worked out / tested out / reworked / retested
by somebody else. As long as you put it together correctly, it
worked and was a good radio.

These days there aren’t a lot of folks selling kit GPSDO’s. Even
the kit radio business isn’t what it once was. “I’m going to do
a GPSDO” these days generally means a scratch design.

Bob


On Feb 19, 2022, at 2:41 AM, Bill Beam  wrote:

But there is a magazine article

By Brooks Shera, W5OJM.  QST July, 1998.

Following this article I built my unit in 1998 using his PCB and a
Motorola UT+.
It has been running almost continuously since then - almost 25 years.
It has been thru several HP 10811 and 10844 oscillators during that
time.

Even though Brooks is SK his GPSDO is still running.

Regards.
Bill, NL7F



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[time-nuts] Re: Lady Heather clock question

[Arnold Tibus]

Hi Bill,

I have no knowledge of the interfaces and functions.
I am with you, the problem seem to be with the device from Lucent.
I am running successful the original Trimble Tbolt I got from Tom,TvB,
(thanks again Tom!) now since long years. I am happy so far with it, a
good base as 10 MHz reference for all my measurement eqipment.
On top I do recalibrate my PRS10 with the 1PPS output from time to time.
Recently I made a new survey for the antenna position on top of my roof,
essential for good results. Easy to be done thanks to the unbeatable
tool from Mark Sims!

I wish you good results,
73
Arnold, DK2WT



Am 29.07.2021 um 14:20 schrieb B Riches via time-nuts:

  Hi Arnold,
Loaded V5 on another PC.  Did not load V6 yet.  Lucent not connected.  T and U 
change time correctly to utc.
Connected Lucent - T and U would not change time.
With V5 John sent a link to his working Tbolt. When first opened it has the 
error.  T then U corrects the time.
Looks like Lucent is the problem.  Rebooted it and it made no difference.  I 
have another lucent in the shop I will try.
Strange. I thought that LH told Lucent to change time but now think LH does the 
heavy lifting from time code from Lucent since I can change tme from Johns 
tbolt.
I am going to contact john and see if he has heard of lucent issues.  Thanks 
for your ideas - what GPS are you using?
 On Wednesday, July 28, 2021, 11:44:45 PM EDT, Arnold Tibus 
 wrote:

  Bill,
that does sound a bit strange, for me it looks like the program does not
work correct at all. When I change this way between GPS time and UTC LH
does immediately switch the time these 18 secs and does continue working
without a resetting comment.
Did you install this version 6 (the last is v. 6.14 beta) as described?
You have to have installed v 5 before and then to follow the instruction
for the beta version to install on top. John, KE5FX, does provide this
released v. 5 on his homepage. The readme for the settings is in general
still valid. See http://www.ke5fx.com/heather/readme.htm
I think in your case it will perhaps be a good idea to restart the full
installation with v.5 and then proceeding as in the instruction to
switch to the beta version. Mark Sims wrote:'This is just the .exe To
use it you will need to have v5.0 installed and working (from ke5fx.com)
and replace the v5.0 heather.exe file with this one (backup your old
.exe first).' That should then work properly. I am running Win 10 pro 64
w/o any hazzle with LH 6.14.

Good luck!

73
Arnold, DK2WT



Am 29.07.2021 um 03:30 schrieb B Riches via time-nuts:

   Hi Arnold,
I Tried that - hit t then u - clock program said resetting and will take a bid. 
 Still did not work.  Any other ideas?
73,
Bill
       On Wednesday, July 28, 2021, 07:23:28 PM EDT, Arnold Tibus 
 wrote:

   Bill, it is quite easy:
When running LH type 'T',
you will then see the list 'Reference'
then hit 'U' for UTC-time.
This should resolve the problem.

I had the same effect before
confusing on top left side is
showing 'UTC ofs: 18'
but this is only the information
for the difference GPS/ UTC time I understand.
But LH was still running with GPS-time setting.
Hope this will help you.

kind regards

Arnold, DK2WT


Am 29.07.2021 um 00:04 schrieb B Riches via time-nuts:

How can a make my LH V6.1 clock show time equal to UTC time?  It is 18 seconds 
fast = to 18 second offset.
Set up:
Windoze 10
simple con fig file = /3  /rx  /tz=-4edst
KS24361 - REF0 GPS
UTC time in greenDate, Week, TOW in yellowDate 28 Jul 2021  ro Week 2160UTC 
ofs:18 in white
When programming is running and I enter rxx/17 clock = UTC time but receiver 
has shut down.
What am I doing wrong?
Thanks for any help.
73,
Bill, WA2DVUCape May, NJ
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[time-nuts] Re: Lady Heather clock question

[Arnold Tibus]

Bill,
that does sound a bit strange, for me it looks like the program does not
work correct at all. When I change this way between GPS time and UTC LH
does immediately switch the time these 18 secs and does continue working
without a resetting comment.
Did you install this version 6 (the last is v. 6.14 beta) as described?
You have to have installed v 5 before and then to follow the instruction
for the beta version to install on top. John, KE5FX, does provide this
released v. 5 on his homepage. The readme for the settings is in general
still valid. See http://www.ke5fx.com/heather/readme.htm
I think in your case it will perhaps be a good idea to restart the full
installation with v.5 and then proceeding as in the instruction to
switch to the beta version. Mark Sims wrote:'This is just the .exe To
use it you will need to have v5.0 installed and working (from ke5fx.com)
and replace the v5.0 heather.exe file with this one (backup your old
.exe first).' That should then work properly. I am running Win 10 pro 64
w/o any hazzle with LH 6.14.

Good luck!

73
Arnold, DK2WT



Am 29.07.2021 um 03:30 schrieb B Riches via time-nuts:

  Hi Arnold,
I Tried that - hit t then u - clock program said resetting and will take a bid. 
 Still did not work.  Any other ideas?
73,
Bill
 On Wednesday, July 28, 2021, 07:23:28 PM EDT, Arnold Tibus 
 wrote:

  Bill, it is quite easy:
When running LH type 'T',
you will then see the list 'Reference'
then hit 'U' for UTC-time.
This should resolve the problem.

I had the same effect before
confusing on top left side is
showing 'UTC ofs: 18'
but this is only the information
for the difference GPS/ UTC time I understand.
But LH was still running with GPS-time setting.
Hope this will help you.

kind regards

Arnold, DK2WT


Am 29.07.2021 um 00:04 schrieb B Riches via time-nuts:

How can a make my LH V6.1 clock show time equal to UTC time?  It is 18 seconds 
fast = to 18 second offset.
Set up:
Windoze 10
simple con fig file = /3  /rx  /tz=-4edst
KS24361 - REF0 GPS
UTC time in greenDate, Week, TOW in yellowDate 28 Jul 2021  ro Week 2160UTC 
ofs:18 in white
When programming is running and I enter rxx/17 clock = UTC time but receiver 
has shut down.
What am I doing wrong?
Thanks for any help.
73,
Bill, WA2DVUCape May, NJ
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[time-nuts] Re: Lady Heather clock question

[Arnold Tibus]

Bill, it is quite easy:
When running LH type 'T',
you will then see the list 'Reference'
then hit 'U' for UTC-time.
This should resolve the problem.

I had the same effect before
confusing on top left side is
showing 'UTC ofs: 18'
but this is only the information
for the difference GPS/ UTC time I understand.
But LH was still running with GPS-time setting.
Hope this will help you.

kind regards

Arnold, DK2WT


Am 29.07.2021 um 00:04 schrieb B Riches via time-nuts:

How can a make my LH V6.1 clock show time equal to UTC time?  It is 18 seconds 
fast = to 18 second offset.
Set up:
Windoze 10
simple con fig file = /3  /rx  /tz=-4edst
KS24361 - REF0 GPS
UTC time in greenDate, Week, TOW in yellowDate 28 Jul 2021  ro Week 2160UTC 
ofs:18 in white
When programming is running and I enter rxx/17 clock = UTC time but receiver 
has shut down.
What am I doing wrong?
Thanks for any help.
73,
Bill, WA2DVUCape May, NJ
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Re: [time-nuts] Ublox 8T

[Arnold Tibus]

Sorry Bert, sorry for the confusion,
that is a typing error on my side, the replacement-board I have from the
US company is equipped with *NEO-M8T* !

Arnold, DK2WT


Am 12.12.2020 um 00:31 schrieb ew via time-nuts:

First we do not know how old the units are on ebay, second  you say your board 
has LEA and what does NEO have to do with it. If we find out that these units 
are old I am sure time nuts will find an answer and you will be able to update 
the units you bought.                                                           
                                                                                
                       Bert Kehren                                              
                                                                                
                                      In a message dated 12/11/2020 5:24:56 PM 
Eastern Standard Time, arnold.ti...@gmx.de writes:
Many thanks to all the timenuts for these interesting informations
concerning *M8T* and for all other good ideas.

My bad, I did not look careful enough to realize that in the ebay
offer mentioned is not a *NEO* M8T but a *LEA* and I did order 2 units
... Fortunately that is not expensive. (Thank you Matthias, I did not
know the difference before!).

No I do not want to build my own module, I do have another problem.
When I bought years ago a professional replacement board from a well
known US-company equipped with the LEA-M8T I got it delivered with the
1st firmware which is not yet capable to work correct with GALILEO
Satellites which I want to receive as well.

The next bad point is, here in Germany I cannot get the new firmware to
update the module (I had asked the representative for M8T). Sending it
back and forth to the US-Company (insured an then on top the customs
problem) is far out to be interesting ... so I falled into the trap with
this offer. I thought to exchange just the receiver on the boards ...
Perhaps somewhen I will find the correct new firmware to load onto the
old original *NEO-M8T* ...

In meantime I will continue working with my good old Thunderbolt.

Many thanks to everybody
   and good and healthy Xmas Time
and good luck for all your projects!

Arnold, DK2WT





Am 10.12.2020 um 10:04 schrieb Matthias Welwarsky:

Dear all,

If you go shopping for existing breakout boards:

The ebay listing is for the *LEA-M8T*. It is mechanically and electrically
different from the *NEO-M8T*.

BR,
Matthias

On Montag, 7. Dezember 2020 14:25:35 CET ew via time-nuts wrote:

With not much happening on Ublox 9T I went back looking at 8T in support for
Jim Harnan's next generation GPSDO.. Shopping on ebay I ran across this
super deal. No financial interest but we have bought from him repeatedly no
problem. There is a reason he has 100%.. We have offered $ 15 for three
each all accepted.                                            Bert Kehren


https://www.ebay.com/itm/ON-SALE-1-U-BLOX-ublox-LEA-M8T-0-10-HUAWEI-GPS-Mod
ule/333753811808?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

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Re: [time-nuts] Ublox 8T

[Arnold Tibus]

Many thanks to all the timenuts for these interesting informations
concerning *M8T* and for all other good ideas.

My bad, I did not look careful enough to realize that in the ebay
offer mentioned is not a *NEO* M8T but a *LEA* and I did order 2 units
... Fortunately that is not expensive. (Thank you Matthias, I did not
know the difference before!).

No I do not want to build my own module, I do have another problem.
When I bought years ago a professional replacement board from a well
known US-company equipped with the LEA-M8T I got it delivered with the
1st firmware which is not yet capable to work correct with GALILEO
Satellites which I want to receive as well.

The next bad point is, here in Germany I cannot get the new firmware to
update the module (I had asked the representative for M8T). Sending it
back and forth to the US-Company (insured an then on top the customs
problem) is far out to be interesting ... so I falled into the trap with
this offer. I thought to exchange just the receiver on the boards ...
Perhaps somewhen I will find the correct new firmware to load onto the
old original *NEO-M8T* ...

In meantime I will continue working with my good old Thunderbolt.

Many thanks to everybody
 and good and healthy Xmas Time
and good luck for all your projects!

Arnold, DK2WT





Am 10.12.2020 um 10:04 schrieb Matthias Welwarsky:

Dear all,

If you go shopping for existing breakout boards:

The ebay listing is for the *LEA-M8T*. It is mechanically and electrically
different from the *NEO-M8T*.

BR,
Matthias

On Montag, 7. Dezember 2020 14:25:35 CET ew via time-nuts wrote:

With not much happening on Ublox 9T I went back looking at 8T in support for
Jim Harnan's next generation GPSDO.. Shopping on ebay I ran across this
super deal. No financial interest but we have bought from him repeatedly no
problem. There is a reason he has 100%.. We have offered $ 15 for three
each all accepted. Bert Kehren


https://www.ebay.com/itm/ON-SALE-1-U-BLOX-ublox-LEA-M8T-0-10-HUAWEI-GPS-Mod
ule/333753811808?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2060353.m1438.l2649

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Re: [time-nuts] Using speaker / earphone for PPS testing (not a question)

[Arnold Tibus]

Timenuts, Gentlemen, hello!

I would like to make my little contribution to this discussion showing
how I implemented my solution in my built PRS10 Box.
For PPS and 10 MHz reference I am running since years successfully a
Trimble Thunderbold together with the antenna fixed on the rooftop of my
house (see pic).

My PRS10 together with the stretcher of the 10µs long PPS pulse to about
250ms do work like a charm already more then 12 months driving LEDs.
This way I can easy visually check the PRS10.
By the way, the PPS output of Thunderbolt, also 10µs long, can as well
be visualized with this LED driver. But I had no problem to see the
pulse on my very old 100MHz Tektronix analog scope (but this is not very
convenient for daily check :-(  ).

As pictures do say more then 1000 words, I want to share the pictures of
my hardware for limited time for private timenut use, showing my way to
solve the problems with available tools and parts (beside eg. the RbO,
Thunderbold, Antenna and other used parts ;-) ).
Here you can open, view and/ or copy my pictures if you want:
https://my.hidrive.com/share/wyaryf.3uq

Comments?
Enjoy!

kind regards,
Arnold, DK2WT


Am 21.04.2020 um 04:25 schrieb Taka Kamiya via time-nuts:

Maybe everyone but I knew, but I just did this and found it useful.
1 pps signal from some GPS are notoriously narrow and difficult to sync on and 
see on scopes.  LED will barely light if some kind of stretcher is not used.  
If your purpose is ONLY to see if it's there or not, hook up a small speaker, 
earphone, amplified or not, and you can hear the tick-tick sound.

I like DIYing and many times, I wonder if pps distribution circuit is working.  
I can tell a very short pulse that will barely register on LED is clearly 
audible.
I thought I'd share.

---
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
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Re: [time-nuts] Power glitch - Sat morning

[Arnold Tibus]

Hello timenuts,
just a quick answer from a standard user in DL (living in private house):

Am 01.04.2020 um 19:14 schrieb Mark Spencer:

Would a time nut in Europe in a typical single family home have access to all 
three phases ?


In general, Yes!
At the house entry there are always the 3 phases delivered and wired to
the counter.
It is up to the owner how he wires and uses the 3 phase (230/400V 50Hz)
then. For lamps and plugs only 1 Phase is wired, but for bigger
apparatus like kitchen and sometimes washing machines 3 phases are
provided.
In the garage/workshop a use of 3 phases is quite often for machines.
I have as well several 3 Phase wall plugs in the shack.

In Flats one will find only one phase beside for the kitchen.
But the 3 phases are normally wired to the fuse and counter box today.



If so would there be any benefit to monitoring the frequency of each phase ?


No, because the 3 phases are generated and provided via 3phase
transformers in the village together (fixed 120°)!



Mark Spencer


Arnold, DK2WT



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Re: [time-nuts] Paper tip: Atomic Clocks for Geodesy

[Arnold Tibus]

Many thanks Ole,
I just read it, in fact very interesting!
regards
Arnold

Am 07.05.2019 um 12:48 schrieb Ole Petter Ronningen:

Hi, all

I just stumbled across a nice review paper from last year: (
https://arxiv.org/ftp/arxiv/papers/1803/1803.01585.pdf) that perhaps others
will find interesting.

Primarily geared towards geodesy as the title indicates, but it also looks
at several techniques of interest to time-nuts, such as optical clocks and
state of the art time transfer. Also I enjoyed the reminder/example of why
precision in timing matters..

The full abstract of the paper:

We review experimental progress on optical atomic clocks and frequency
transfer, and consider the prospects of using these technologies for
geodetic measurements. Today, optical atomic frequency standards have
reached relative frequency inaccuracies below 10-17, opening new fields of
fundamental and applied research. The dependence of atomic frequencies on
the gravitational potential makes atomic clocks ideal candidates for the
search for deviations in the predictions of Einstein's general relativity,
tests of modern unifying theories and the development of new gravity field
sensors. In this review, we introduce the concepts of optical atomic clocks
and present the status of international clock development and comparison.
Besides further improvement in stability and accuracy of today's best
clocks, a large effort is put into increasing the reliability and
technological readiness for applications outside of specialized
laboratories with compact, portable devices. With relative frequency
uncertainties of 10-18, comparisons of optical frequency standards are
foreseen to contribute together with satellite and terrestrial data to the
precise determination of fundamental height reference systems in geodesy
with a resolution at the cm-level. The long-term stability of atomic
standards will deliver excellent long-term height references for geodetic
measurements and for the modelling and understanding of our Earth.

Enjoy,
Ole
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Re: [time-nuts] Distribution amplifier for 10MHz

[Arnold Tibus]

Ignacio,
you will find it looking on Didier's page under 'manuals'
and then searching e.g with 'steinmetz'.

saludos, 73
Arnold, DK2WT


Am 17.03.2019 um 12:15 schrieb EB4APL:

Hi,

It seems that Didier has changed his website somewhat and the links 
don't point to the referred documents. Either I was not able to find 
them navigating within the site.


Regards,
Ignacio, EB4APL



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Re: [time-nuts] White Rabbit time distribution performance

[Arnold Tibus]

Thank you very much Mattia -
I am interested to read and to learn - but I see:
"Sign in or purchase", not loved by everybody, and I have no membership,
a pity, sorry.

My best wishes,

Arnold, DK2WT


Am 02.07.2018 um 21:37 schrieb Mattia Rizzi:

Hello!
I published a paper on WR time distribution performance that you might
consider interesting. It's available at IEEExplorer:
https://ieeexplore.ieee.org/document/8400550/

Abstract:
This article investigates the ultimate limits of White Rabbit (WR), an
high-accuracy time distribution system based on FPGA. The knowledge of such
limits is essential for new emerging applications that are evaluating WR.
In this article, we identify and study the key elements in the WR
synchronization: the Digital Dual Mixer Time Difference phase detector and
the Gigabit Ethernet transceiver. The benchmarks and experimental analysis
of these key elements allow us to determine the WR Switch performance
limits and evaluate their evolution with newer FPGAs. The identified
performance limits are achievable by the present-day generation of WR
Switch. The ultimate limits of short-term synchronization performance due
to FPGA implementation have been derived through analysis and then
demonstrated using the existing WR Switch enhanced with an additional
daughter-board. This combination (WR Switch and daughter-board) achieves a
tenfold improvement in terms of phase noise, jitter and shortterm stability
with respect to the current WR performance. Both phase detectors and
Gigabit transceivers have a similar phase noise contribution equal to a
short-term stability of MDEV 4E-13 at τ=1 s (dominated by flicker PM noise).

cheers
Mattia
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