Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Dave Daniel]

Answers inline

> On Jan 19, 2021, at 16:27, Bob kb8tq  wrote:
> 
> Hi
> 
> Assuming the goal is a normal ADEV or xDEV sort of calculation:
> 
> If you replace the raw phase values with zero that can mess things up
> 
> 0 seconds +20 ns
> 1 seconds +22 ns
> 2 seconds +23 ns
> 3 seconds +25 ns
> 4 seconds +27ns
> 5 seconds +29 ns
> 
> If you “loose” one of those 20 to 30 ns values and replace it with zero, you 
> have significantly
> changed the data set.

Ok

> 
> Even if you are looking at deltas,

Nope. It doesn’t work for deltas. 

> zero stuffing would be problematic with that
> (contrived) phase data set. 
> 
> 1 seconds +2
> 2 seconds +1
> 3 seconds +2
> 4 seconds +2
> 5 seconds +2
> 
> If the objective is something like a PLL then “hold at the last value” is the 
> only practical
> answer to the question. You don’t *have* the next value and you need to stuff 
> something
> into the control loop computation.

For a control loop, certainly. For just generating the waveform after DAC using 
interploation, it works well.

So, my suggestion doesn’t cover all use cases, and I learned something. That 
makes it a good day.

DaveD
> 
> Bob
> 
> 
>> On Jan 19, 2021, at 1:37 PM, Dave Daniel  wrote:
>> 
>> Or one can replace those values with zero. That eliminates them; averaging 
>> then proceeds without those values altering the most probable correct 
>> average.
>> 
>> DaveD
>> 
>>> On Jan 19, 2021, at 08:49, Bob kb8tq  wrote:
>>> 
>>> Hi
>>> 
>>> The normal approach to filling a gap is to put in a point that is the 
>>> average
>>> of the two adjacent points. The assumption is that this is a “safe” value 
>>> that
>>> will not blow up the result. That’s probably ok if it is done rarely. The 
>>> risk is
>>> that you are running a filter process (averaging is a low pass filter). 
>>> 
>>> If you pull out a *lot* of outliers and replace them, you are doing a lot 
>>> of filtering.
>>> Since you are measuring noise, filtering is very likely to improve the 
>>> result. 
>>> The question becomes - how representative is the result after a lot of this 
>>> or 
>>> that has been done? 
>>> 
>>> Obviously the answer to all this depends on what you are trying to do. If 
>>> you
>>> are running a control loop and the output improves, that’s fine. If you are 
>>> trying to provide an accurate measure of noise …. maybe not so much :) 
>>> 
>>> Bob
>>> 
 On Jan 19, 2021, at 2:15 AM, Gilles Clement  wrote:
 
 Hi, 
 Yes outliers removal creates gap in Stable32.
 The « fill »  function can fills gaps with interpolated values. 
 It does not change much the graphs, except in the low Tau area (see 
 attached). 
 Do you know a discussion of impact of outliers removal ? 
 Gilles. 
 
 
 
> Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
> 
> Hi
> 
> As you throw away samples that are far off the mean, you reduce the sample
> rate ( or at least create gaps in the record). Dealing with that could be 
> difficult.
> 
> Bob
> 
>>> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
>>> 
>>> Hi
>>> 
>>> Very cool !!!
>>> 
>>> The red trace is obviously the one to focus on. Some sort of digital 
>>> loop that
>>> only operates under the “known good” conditions would seem to make 
>>> sense. 
>>> 
>>> Thanks for sharing 
>>> 
>>> Bob
>> 
>> Hi,
>> I tried something with the idea to consider night records fluctuations 
>> as « outliers » as compared to day records. 
>> Indeed the 3 days record mean value is flat and the histogram quite 
>> gaussian. 
>> So I processed the 3 days record (green trace) with Stable32’s « Check 
>> Function »,
>> while removing outliers with decreasing values of the Sigma Factor. The 
>> graph below shows the outcome. 
>> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
>> record (red trace). 
>> Would this be a workable approach ? 
>> Best, 
>> Gilles. 
>> 
>> 
>> 
>> 
>> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Michael Wouters]

Hello Gilles

There's a reasonable way of treating data with gaps in it:

https://iopscience.iop.org/article/10.1088/0026-1394/45/6/S19

Essentially, any averaging interval with missing data is dropped from
the ADEV summation.
This reduces the number of intervals averaged over and increases the
uncertainty but is better than faking data.

Stable32 provides an  implementation of the algorithm. See p18 of the manual.

Cheers
Michael




On Tue, Jan 19, 2021 at 6:18 PM Gilles Clement  wrote:
>
> Hi,
> Yes outliers removal creates gap in Stable32.
> The « fill »  function can fills gaps with interpolated values.
> It does not change much the graphs, except in the low Tau area (see attached).
> Do you know a discussion of impact of outliers removal ?
> Gilles.
>
>
>
> > Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
> >
> > Hi
> >
> > As you throw away samples that are far off the mean, you reduce the sample
> > rate ( or at least create gaps in the record). Dealing with that could be 
> > difficult.
> >
> > Bob
> >
> >> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
> >>
> >>> Hi
> >>>
> >>> Very cool !!!
> >>>
> >>> The red trace is obviously the one to focus on. Some sort of digital loop 
> >>> that
> >>> only operates under the “known good” conditions would seem to make sense.
> >>>
> >>> Thanks for sharing
> >>>
> >>> Bob
> >>
> >> Hi,
> >> I tried something with the idea to consider night records fluctuations as 
> >> « outliers » as compared to day records.
> >> Indeed the 3 days record mean value is flat and the histogram quite 
> >> gaussian.
> >> So I processed the 3 days record (green trace) with Stable32’s « Check 
> >> Function »,
> >> while removing outliers with decreasing values of the Sigma Factor. The 
> >> graph below shows the outcome.
> >> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
> >> record (red trace).
> >> Would this be a workable approach ?
> >> Best,
> >> Gilles.
> >>
> >>
> >>
> >>
> >>
> >> ___
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> >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> >> and follow the instructions there.
> >
> >
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Bob kb8tq]

Hi

Assuming the goal is a normal ADEV or xDEV sort of calculation:

If you replace the raw phase values with zero that can mess things up

0 seconds +20 ns
1 seconds +22 ns
2 seconds +23 ns
3 seconds +25 ns
4 seconds +27ns
5 seconds +29 ns

If you “loose” one of those 20 to 30 ns values and replace it with zero, you 
have significantly
changed the data set.

Even if you are looking at deltas, zero stuffing would be problematic with that
(contrived) phase data set. 

1 seconds +2
2 seconds +1
3 seconds +2
4 seconds +2
5 seconds +2

If the objective is something like a PLL then “hold at the last value” is the 
only practical
answer to the question. You don’t *have* the next value and you need to stuff 
something
into the control loop computation.

Bob


> On Jan 19, 2021, at 1:37 PM, Dave Daniel  wrote:
> 
> Or one can replace those values with zero. That eliminates them; averaging 
> then proceeds without those values altering the most probable correct average.
> 
> DaveD
> 
>> On Jan 19, 2021, at 08:49, Bob kb8tq  wrote:
>> 
>> Hi
>> 
>> The normal approach to filling a gap is to put in a point that is the average
>> of the two adjacent points. The assumption is that this is a “safe” value 
>> that
>> will not blow up the result. That’s probably ok if it is done rarely. The 
>> risk is
>> that you are running a filter process (averaging is a low pass filter). 
>> 
>> If you pull out a *lot* of outliers and replace them, you are doing a lot of 
>> filtering.
>> Since you are measuring noise, filtering is very likely to improve the 
>> result. 
>> The question becomes - how representative is the result after a lot of this 
>> or 
>> that has been done? 
>> 
>> Obviously the answer to all this depends on what you are trying to do. If you
>> are running a control loop and the output improves, that’s fine. If you are 
>> trying to provide an accurate measure of noise …. maybe not so much :) 
>> 
>> Bob
>> 
>>> On Jan 19, 2021, at 2:15 AM, Gilles Clement  wrote:
>>> 
>>> Hi, 
>>> Yes outliers removal creates gap in Stable32.
>>> The « fill »  function can fills gaps with interpolated values. 
>>> It does not change much the graphs, except in the low Tau area (see 
>>> attached). 
>>> Do you know a discussion of impact of outliers removal ? 
>>> Gilles. 
>>> 
>>> 
>>> 
 Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
 
 Hi
 
 As you throw away samples that are far off the mean, you reduce the sample
 rate ( or at least create gaps in the record). Dealing with that could be 
 difficult.
 
 Bob
 
>> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
>> 
>> Hi
>> 
>> Very cool !!!
>> 
>> The red trace is obviously the one to focus on. Some sort of digital 
>> loop that
>> only operates under the “known good” conditions would seem to make 
>> sense. 
>> 
>> Thanks for sharing 
>> 
>> Bob
> 
> Hi,
> I tried something with the idea to consider night records fluctuations as 
> « outliers » as compared to day records. 
> Indeed the 3 days record mean value is flat and the histogram quite 
> gaussian. 
> So I processed the 3 days record (green trace) with Stable32’s « Check 
> Function »,
> while removing outliers with decreasing values of the Sigma Factor. The 
> graph below shows the outcome. 
> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
> record (red trace). 
> Would this be a workable approach ? 
> Best, 
> Gilles. 
> 
> 
> 
> 
> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Dave Daniel]

Or one can replace those values with zero. That eliminates them; averaging then 
proceeds without those values altering the most probable correct average.

DaveD

> On Jan 19, 2021, at 08:49, Bob kb8tq  wrote:
> 
> Hi
> 
> The normal approach to filling a gap is to put in a point that is the average
> of the two adjacent points. The assumption is that this is a “safe” value that
> will not blow up the result. That’s probably ok if it is done rarely. The 
> risk is
> that you are running a filter process (averaging is a low pass filter). 
> 
> If you pull out a *lot* of outliers and replace them, you are doing a lot of 
> filtering.
> Since you are measuring noise, filtering is very likely to improve the 
> result. 
> The question becomes - how representative is the result after a lot of this 
> or 
> that has been done? 
> 
> Obviously the answer to all this depends on what you are trying to do. If you
> are running a control loop and the output improves, that’s fine. If you are 
> trying to provide an accurate measure of noise …. maybe not so much :) 
> 
> Bob
> 
>> On Jan 19, 2021, at 2:15 AM, Gilles Clement  wrote:
>> 
>> Hi, 
>> Yes outliers removal creates gap in Stable32.
>> The « fill »  function can fills gaps with interpolated values. 
>> It does not change much the graphs, except in the low Tau area (see 
>> attached). 
>> Do you know a discussion of impact of outliers removal ? 
>> Gilles. 
>> 
>> 
>> 
>>> Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
>>> 
>>> Hi
>>> 
>>> As you throw away samples that are far off the mean, you reduce the sample
>>> rate ( or at least create gaps in the record). Dealing with that could be 
>>> difficult.
>>> 
>>> Bob
>>> 
> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
> 
> Hi
> 
> Very cool !!!
> 
> The red trace is obviously the one to focus on. Some sort of digital loop 
> that
> only operates under the “known good” conditions would seem to make sense. 
> 
> Thanks for sharing 
> 
> Bob
 
 Hi,
 I tried something with the idea to consider night records fluctuations as 
 « outliers » as compared to day records. 
 Indeed the 3 days record mean value is flat and the histogram quite 
 gaussian. 
 So I processed the 3 days record (green trace) with Stable32’s « Check 
 Function »,
 while removing outliers with decreasing values of the Sigma Factor. The 
 graph below shows the outcome. 
 The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
 record (red trace). 
 Would this be a workable approach ? 
 Best, 
 Gilles. 
 
 
 
 
 
 ___
 time-nuts mailing list -- time-nuts@lists.febo.com
 To unsubscribe, go to 
 http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
 and follow the instructions there.
>>> 
>>> 
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>> 
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> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Bob kb8tq]

Hi

The normal approach to filling a gap is to put in a point that is the average
of the two adjacent points. The assumption is that this is a “safe” value that
will not blow up the result. That’s probably ok if it is done rarely. The risk 
is
that you are running a filter process (averaging is a low pass filter). 

If you pull out a *lot* of outliers and replace them, you are doing a lot of 
filtering.
Since you are measuring noise, filtering is very likely to improve the result. 
The question becomes - how representative is the result after a lot of this or 
that has been done? 

Obviously the answer to all this depends on what you are trying to do. If you
are running a control loop and the output improves, that’s fine. If you are 
trying to provide an accurate measure of noise …. maybe not so much :) 

Bob

> On Jan 19, 2021, at 2:15 AM, Gilles Clement  wrote:
> 
> Hi, 
> Yes outliers removal creates gap in Stable32.
> The « fill »  function can fills gaps with interpolated values. 
> It does not change much the graphs, except in the low Tau area (see 
> attached). 
> Do you know a discussion of impact of outliers removal ? 
> Gilles. 
> 
> 
> 
>> Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
>> 
>> Hi
>> 
>> As you throw away samples that are far off the mean, you reduce the sample
>> rate ( or at least create gaps in the record). Dealing with that could be 
>> difficult.
>> 
>> Bob
>> 
>>> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
>>> 
 Hi
 
 Very cool !!!
 
 The red trace is obviously the one to focus on. Some sort of digital loop 
 that
 only operates under the “known good” conditions would seem to make sense. 
 
 Thanks for sharing 
 
 Bob
>>> 
>>> Hi,
>>> I tried something with the idea to consider night records fluctuations as « 
>>> outliers » as compared to day records. 
>>> Indeed the 3 days record mean value is flat and the histogram quite 
>>> gaussian. 
>>> So I processed the 3 days record (green trace) with Stable32’s « Check 
>>> Function »,
>>> while removing outliers with decreasing values of the Sigma Factor. The 
>>> graph below shows the outcome. 
>>> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
>>> record (red trace). 
>>> Would this be a workable approach ? 
>>> Best, 
>>> Gilles. 
>>> 
>>> 
>>> 
>>> 
>>> 
>>> ___
>>> time-nuts mailing list -- time-nuts@lists.febo.com
>>> To unsubscribe, go to 
>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>>> and follow the instructions there.
>> 
>> 
>> ___
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>> and follow the instructions there.
> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Gilles Clement]

Hi, 
Yes outliers removal creates gap in Stable32.
The « fill »  function can fills gaps with interpolated values. 
It does not change much the graphs, except in the low Tau area (see attached). 
Do you know a discussion of impact of outliers removal ? 
Gilles. 



> Le 18 janv. 2021 à 22:06, Bob kb8tq  a écrit :
> 
> Hi
> 
> As you throw away samples that are far off the mean, you reduce the sample
> rate ( or at least create gaps in the record). Dealing with that could be 
> difficult.
> 
> Bob
> 
>> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
>> 
>>> Hi
>>> 
>>> Very cool !!!
>>> 
>>> The red trace is obviously the one to focus on. Some sort of digital loop 
>>> that
>>> only operates under the “known good” conditions would seem to make sense. 
>>> 
>>> Thanks for sharing 
>>> 
>>> Bob
>> 
>> Hi,
>> I tried something with the idea to consider night records fluctuations as « 
>> outliers » as compared to day records. 
>> Indeed the 3 days record mean value is flat and the histogram quite 
>> gaussian. 
>> So I processed the 3 days record (green trace) with Stable32’s « Check 
>> Function »,
>> while removing outliers with decreasing values of the Sigma Factor. The 
>> graph below shows the outcome. 
>> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
>> record (red trace). 
>> Would this be a workable approach ? 
>> Best, 
>> Gilles. 
>> 
>> 
>> 
>> 
>> 
>> ___
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>> and follow the instructions there.
> 
> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Bob kb8tq]

Hi

As you throw away samples that are far off the mean, you reduce the sample
rate ( or at least create gaps in the record). Dealing with that could be 
difficult.

Bob

> On Jan 18, 2021, at 1:33 PM, Gilles Clement  wrote:
> 
>> Hi
>> 
>> Very cool !!!
>> 
>> The red trace is obviously the one to focus on. Some sort of digital loop 
>> that
>> only operates under the “known good” conditions would seem to make sense. 
>> 
>> Thanks for sharing 
>> 
>> Bob
> 
> Hi,
> I tried something with the idea to consider night records fluctuations as « 
> outliers » as compared to day records. 
> Indeed the 3 days record mean value is flat and the histogram quite gaussian. 
> So I processed the 3 days record (green trace) with Stable32’s « Check 
> Function »,
> while removing outliers with decreasing values of the Sigma Factor. The graph 
> below shows the outcome. 
> The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day 
> record (red trace). 
> Would this be a workable approach ? 
> Best, 
> Gilles. 
> 
> 
> 
> 
> 
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> time-nuts mailing list -- time-nuts@lists.febo.com
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Gilles Clement]

> Hi
> 
> Very cool !!!
> 
> The red trace is obviously the one to focus on. Some sort of digital loop that
> only operates under the “known good” conditions would seem to make sense. 
> 
> Thanks for sharing 
> 
> Bob

Hi,
I tried something with the idea to consider night records fluctuations as « 
outliers » as compared to day records. 
Indeed the 3 days record mean value is flat and the histogram quite gaussian. 
So I processed the 3 days record (green trace) with Stable32’s « Check Function 
»,
while removing outliers with decreasing values of the Sigma Factor. The graph 
below shows the outcome. 
The graph with Sigma=0.8 (blue trace) connects rather well with the 1Day record 
(red trace). 
Would this be a workable approach ? 
Best, 
Gilles. 





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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[JF PICARD via time-nuts]

 HP journal
 On Saturday, January 16, 2021, 12:29:24 PM GMT+1, Gilles Clement 
 wrote:  
 
 Hi Paul,
> I guess I would ask what the goal of the effort might be.
> It seems like a good answer. One thing I was amazed buy was that back in
> the 1960s HP wrote some papers on using WWVB. What they did was check the
> offset at distance everyday about the same time. This offered quite a bit
> more accuracy and avoided all of the night propagation effects. Essentially
> from day to day the path is about the same.
Interesting, do you know where I could find such papers ? 
> If your system is stable enough could you simply put it in holdover at
> night?
I don’t think so. It is quite sensitive and when uncoupled the VCO drifts 
significantly.
> The other question I had is how do you then use the locked crystal
> oscillator at 5.184 Mhz?
> Does it somehow divide down to a useful number?

5184000 =2e9 × 3e4 × 5e3 which leads to 200 possible divisors 
Among which : 1000 ; 2000 ; 4000 ; 6000 ; 8000 ; 9000 ; 162k ; 192k ….
I am using the PPS to lock other oscillators
One could use another OCXO frequency (typical 10MHz) and phase lock 
on an intermediate common divisor such as 2000Hz or 4000Hz etc...
I am currently looking at this option but it is more
complex and not sure it would provide better performances.  
> Nice project and good luck. Looking forward to hearing more.
> Regards
> Paul
> WB8TSL

Thank you, 
Best, 
Gilles. 

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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Gilles Clement]

Hi Paul,
> I guess I would ask what the goal of the effort might be.
> It seems like a good answer. One thing I was amazed buy was that back in
> the 1960s HP wrote some papers on using WWVB. What they did was check the
> offset at distance everyday about the same time. This offered quite a bit
> more accuracy and avoided all of the night propagation effects. Essentially
> from day to day the path is about the same.
Interesting, do you know where I could find such papers ? 
> If your system is stable enough could you simply put it in holdover at
> night?
I don’t think so. It is quite sensitive and when uncoupled the VCO drifts 
significantly.
> The other question I had is how do you then use the locked crystal
> oscillator at 5.184 Mhz?
> Does it somehow divide down to a useful number?

5184000 =2e9 × 3e4 × 5e3 which leads to 200 possible divisors 
Among which : 1000 ; 2000 ; 4000 ; 6000 ; 8000 ; 9000 ; 162k ; 192k ….
I am using the PPS to lock other oscillators
One could use another OCXO frequency (typical 10MHz) and phase lock 
on an intermediate common divisor such as 2000Hz or 4000Hz etc...
I am currently looking at this option but it is more
complex and not sure it would provide better performances.   
> Nice project and good luck. Looking forward to hearing more.
> Regards
> Paul
> WB8TSL

Thank you, 
Best, 
Gilles. 

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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[John Moran, Scawby Design]

There is an earlier NIST publication on the problems here -

https://nvlpubs.nist.gov/nistpubs/jres/64D/jresv64Dn3p239_A1b.pdf

John


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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Andy Talbot]

It's a custom LF receiver I put together, a direct conversion downconverter
to 1kHz. Then bandpass sampling to an I/Q data steam, at 12 bit resolution
sent using RS422 o a PC. All frequency conversion and sampling is locked to
a master 10MHz clock.  The interface also includes time stamping from a GPS
module.

PC software takes the data steam, applies a small optional frequency
offset, needed to take out DDS frequency setting resolution, displays raw
input on a vector scope.  It then decimated filters the data down to
sampling rate in teh Hz to sub-Hz region for storage and further analysis
of display.

I originally designed the S/W for use with the  Ebnaut   LF data comms
work, hence the reference to .WAV files with time stamped file names but
its more use as a general tool for monitoroing LF signals.

You can find details here  http://g4jnt.com/Coherent_LF_Receiver.pdf  and
there's a better write up in Jan 2021 edition of RadCom (RSGB Members'
magazine)

Andy
www.g4jnt.com




Virus-free.
www.avg.com

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Fri, 15 Jan 2021 at 23:55, paul swed  wrote:

> What was the program that you used for the plot please?
> Regards
> Paul
> WB8TSL
>
> On Fri, Jan 15, 2021 at 5:54 PM Andy Talbot  wrote:
>
> > I did a plot of the phase of the UK 198kHz longwave transmission to me, a
> > path of about 150km, compared against an HP5061A Caesium standard
> > N
> >
> > early 24 hours duration, covering night time and day time propagation in
> > October.
> >
> > You can observe the wild wandering of both phase and amplitude  during
> > night time due to skywave/groundwave interaction as the ionosphere shifts
> > around.
> >
> > Plot also at
> > http://www.g4jnt.com/DropF/droitwichplot2a.bmp
> > if the attachment doesn't get through
> >
> >
> > [image: DroitwichPlot2a.bmp]
> > Andy
> > www.g4jnt.com
> >
> >
> >
> > <
> >
> http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail
> > >
> > Virus-free.
> > www.avg.com
> > <
> >
> http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail
> > >
> > <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
> >
> > On Fri, 15 Jan 2021 at 21:55, Gilles Clement  wrote:
> >
> > > Hi JF,
> > > DCF77 is more distant, less powerful and probably more polluted
> (77kHz).
> > > Anyhow I would probably not be able to measure better than 10e-11 with
> > > current setup (need a better reference)
> > > Indeed a good and stable phase lock was not easy to reach.
> > > I experienced the day and night huge differences (as documented in
> post)
> > > but nothing specific to phase shifts during sunrise or sunset.
> > > No big difficulties with the ferrite antenna and the receiver design
> > > either (thanks to good stuff from the old radio days probably).
> > > Found that magnetic field antenna (ie: ferrite) appeared much less
> > > sensitive to pollution than electric field antennas.
> > > Naturally bad experience with Led bulbs and vapor gas lamps. You have
> to
> > > chase them all and change to old filament lamps in and around the lab.
> No
> > > issues with computers though.
> > > What I found most challenging (and hence interesting) was the
> following :
> > > - Temperature control, high resolution and high stability (Crystal
> > > oscillator but also for the controller parts, ADC, DAC… )
> > > - PI loop stability (very tricky)
> > > - Matching theory with practice (still work in progress…!)
> > > - Understanding the logic and physics behind behaviors, the real root
> > > cause of problems,
> > > and especially why a « really clever » enhancement - more than often -
> > > actually leads to… performance degradation...
> > > Gilles.
> > >
> > >
> > >
> > > > Le 15 janv. 2021 à 16:57, JF PICARD via time-nuts <
> > > time-nuts@lists.febo.com> a écrit :
> > > >
> > > > Hi,
> > > > 800Kw according to the press release of ANFR. I doubt it is the best
> > > choice : DCF77 is more precise (active hydrogen maser) but a little bit
> > > more distant...
> > > > But the phase lock of a quartz on a VLF signal is not as easy. There
> is
> > > a considerable phase shift in the evening and in the morning with the
> sun
> > > position, big instabilities at these moments and you have a hudge
> > > difference between day and night (10 e-9/8)... Have a look at the Adret
> > > receiver 4101 with its step motor phase lock...The engineering of the
> > > ferrite road antenna is very tricky : temperature coefficient of the
> > > ferrite, subtle tiny out of resonnace tuning, problem of the
> > interferences
> > > from domestic electrnic pollution (computers with sync of monitors, led
> > > drivers...). The archiyecture of the receiver is also tricky : no AGC
> > > (introduces phaseshift), heavy filtering (where : antenna, 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[djl]

Sorry, forgot to include the cite:
LATHAM, D. Diurnal Frequency Variation and Refraction Index. Nature 
Physical Science 234, 157–158 (1971). 
https://doi.org/10.1038/physci234157a0


Don

On 2021-01-15 15:13, Andy Talbot wrote:
I did a plot of the phase of the UK 198kHz longwave transmission to me, 
a

path of about 150km, compared against an HP5061A Caesium standard
N

early 24 hours duration, covering night time and day time propagation 
in

October.

You can observe the wild wandering of both phase and amplitude  during
night time due to skywave/groundwave interaction as the ionosphere 
shifts

around.

Plot also at
http://www.g4jnt.com/DropF/droitwichplot2a.bmp
if the attachment doesn't get through


[image: DroitwichPlot2a.bmp]
Andy
www.g4jnt.com




Virus-free.
www.avg.com

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Fri, 15 Jan 2021 at 21:55, Gilles Clement  
wrote:



Hi JF,
DCF77 is more distant, less powerful and probably more polluted 
(77kHz).

Anyhow I would probably not be able to measure better than 10e-11 with
current setup (need a better reference)
Indeed a good and stable phase lock was not easy to reach.
I experienced the day and night huge differences (as documented in 
post)

but nothing specific to phase shifts during sunrise or sunset.
No big difficulties with the ferrite antenna and the receiver design
either (thanks to good stuff from the old radio days probably).
Found that magnetic field antenna (ie: ferrite) appeared much less
sensitive to pollution than electric field antennas.
Naturally bad experience with Led bulbs and vapor gas lamps. You have 
to
chase them all and change to old filament lamps in and around the lab. 
No

issues with computers though.
What I found most challenging (and hence interesting) was the 
following :

- Temperature control, high resolution and high stability (Crystal
oscillator but also for the controller parts, ADC, DAC… )
- PI loop stability (very tricky)
- Matching theory with practice (still work in progress…!)
- Understanding the logic and physics behind behaviors, the real root
cause of problems,
and especially why a « really clever » enhancement - more than often -
actually leads to… performance degradation...
Gilles.



> Le 15 janv. 2021 à 16:57, JF PICARD via time-nuts <
time-nuts@lists.febo.com> a écrit :
>
> Hi,
> 800Kw according to the press release of ANFR. I doubt it is the best
choice : DCF77 is more precise (active hydrogen maser) but a little 
bit

more distant...
> But the phase lock of a quartz on a VLF signal is not as easy. There is
a considerable phase shift in the evening and in the morning with the 
sun

position, big instabilities at these moments and you have a hudge
difference between day and night (10 e-9/8)... Have a look at the 
Adret

receiver 4101 with its step motor phase lock...The engineering of the
ferrite road antenna is very tricky : temperature coefficient of the
ferrite, subtle tiny out of resonnace tuning, problem of the 
interferences
from domestic electrnic pollution (computers with sync of monitors, 
led

drivers...). The archiyecture of the receiver is also tricky : no AGC
(introduces phaseshift), heavy filtering (where : antenna, 
receiver...)

> On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement <
clemg...@gmail.com> wrote:
>
> Hi,
>
> This is to share current results on a "Long Wave RadioFrequency
Standard" project I have been pursuing for a while.
> Attached are typical ADEV plots and a block diagram of the system.
>
> I live in a crowded city (Paris, France) with no - or very limited -
access to open sky. Not good for GPS.
> However a long wave broadcasting public service is (still) available,
broadcasting time signal for clocks.
> The transmitter is located in Allouis, central France (200km for Paris).
> The signal is quite powerful (1MW) and the carrier (162kHz ) is
stabilized with a Cesium-standard.
>
> I decided to test how far I could go in disciplining a local VCO with
this signal.
>
> As well known, long wave RF has interesting features:
> - Signal is available (almost) everywhere, anytime, in the country
especially inside buildings (even underground !)
> - Quite stable and strong ground wave in day time.
> - Relatively easy antenna and RF signal processing (ferrite rod)
> And there are naturally a number of drawbacks (especially with the
Allouis signal) such as:
> - Much more unstable signal at night (interferences with ionospheric
path)
> - Large phase modulation of the carrier (time signals bits +/- 1 rad
phase modulated).
> - RF perturbations on the signal path.
> -Stop broadcasting for maintenance every Tuesday morning….
>
> Design of the « LWRFDO » was derived and inspired from many references
(including this list naturally).
> Principles are summarized in the attached 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[paul swed]

What was the program that you used for the plot please?
Regards
Paul
WB8TSL

On Fri, Jan 15, 2021 at 5:54 PM Andy Talbot  wrote:

> I did a plot of the phase of the UK 198kHz longwave transmission to me, a
> path of about 150km, compared against an HP5061A Caesium standard
> N
>
> early 24 hours duration, covering night time and day time propagation in
> October.
>
> You can observe the wild wandering of both phase and amplitude  during
> night time due to skywave/groundwave interaction as the ionosphere shifts
> around.
>
> Plot also at
> http://www.g4jnt.com/DropF/droitwichplot2a.bmp
> if the attachment doesn't get through
>
>
> [image: DroitwichPlot2a.bmp]
> Andy
> www.g4jnt.com
>
>
>
> <
> http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail
> >
> Virus-free.
> www.avg.com
> <
> http://www.avg.com/email-signature?utm_medium=email_source=link_campaign=sig-email_content=webmail
> >
> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
>
> On Fri, 15 Jan 2021 at 21:55, Gilles Clement  wrote:
>
> > Hi JF,
> > DCF77 is more distant, less powerful and probably more polluted (77kHz).
> > Anyhow I would probably not be able to measure better than 10e-11 with
> > current setup (need a better reference)
> > Indeed a good and stable phase lock was not easy to reach.
> > I experienced the day and night huge differences (as documented in post)
> > but nothing specific to phase shifts during sunrise or sunset.
> > No big difficulties with the ferrite antenna and the receiver design
> > either (thanks to good stuff from the old radio days probably).
> > Found that magnetic field antenna (ie: ferrite) appeared much less
> > sensitive to pollution than electric field antennas.
> > Naturally bad experience with Led bulbs and vapor gas lamps. You have to
> > chase them all and change to old filament lamps in and around the lab. No
> > issues with computers though.
> > What I found most challenging (and hence interesting) was the following :
> > - Temperature control, high resolution and high stability (Crystal
> > oscillator but also for the controller parts, ADC, DAC… )
> > - PI loop stability (very tricky)
> > - Matching theory with practice (still work in progress…!)
> > - Understanding the logic and physics behind behaviors, the real root
> > cause of problems,
> > and especially why a « really clever » enhancement - more than often -
> > actually leads to… performance degradation...
> > Gilles.
> >
> >
> >
> > > Le 15 janv. 2021 à 16:57, JF PICARD via time-nuts <
> > time-nuts@lists.febo.com> a écrit :
> > >
> > > Hi,
> > > 800Kw according to the press release of ANFR. I doubt it is the best
> > choice : DCF77 is more precise (active hydrogen maser) but a little bit
> > more distant...
> > > But the phase lock of a quartz on a VLF signal is not as easy. There is
> > a considerable phase shift in the evening and in the morning with the sun
> > position, big instabilities at these moments and you have a hudge
> > difference between day and night (10 e-9/8)... Have a look at the Adret
> > receiver 4101 with its step motor phase lock...The engineering of the
> > ferrite road antenna is very tricky : temperature coefficient of the
> > ferrite, subtle tiny out of resonnace tuning, problem of the
> interferences
> > from domestic electrnic pollution (computers with sync of monitors, led
> > drivers...). The archiyecture of the receiver is also tricky : no AGC
> > (introduces phaseshift), heavy filtering (where : antenna, receiver...)
> > > On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement <
> > clemg...@gmail.com> wrote:
> > >
> > > Hi,
> > >
> > > This is to share current results on a "Long Wave RadioFrequency
> > Standard" project I have been pursuing for a while.
> > > Attached are typical ADEV plots and a block diagram of the system.
> > >
> > > I live in a crowded city (Paris, France) with no - or very limited -
> > access to open sky. Not good for GPS.
> > > However a long wave broadcasting public service is (still) available,
> > broadcasting time signal for clocks.
> > > The transmitter is located in Allouis, central France (200km for
> Paris).
> > > The signal is quite powerful (1MW) and the carrier (162kHz ) is
> > stabilized with a Cesium-standard.
> > >
> > > I decided to test how far I could go in disciplining a local VCO with
> > this signal.
> > >
> > > As well known, long wave RF has interesting features:
> > > - Signal is available (almost) everywhere, anytime, in the country
> > especially inside buildings (even underground !)
> > > - Quite stable and strong ground wave in day time.
> > > - Relatively easy antenna and RF signal processing (ferrite rod)
> > > And there are naturally a number of drawbacks (especially with the
> > Allouis signal) such as:
> > > - Much more unstable signal at night (interferences with ionospheric
> > path)
> > > - Large phase modulation of the carrier (time signals bits +/- 1 rad
> > phase modulated).
> > > - RF 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[djl]

Longwave phase is dependent on the weather between your receiver and the 
transmitter...



On 2021-01-15 15:13, Andy Talbot wrote:
I did a plot of the phase of the UK 198kHz longwave transmission to me, 
a

path of about 150km, compared against an HP5061A Caesium standard
N

early 24 hours duration, covering night time and day time propagation 
in

October.

You can observe the wild wandering of both phase and amplitude  during
night time due to skywave/groundwave interaction as the ionosphere 
shifts

around.

Plot also at
http://www.g4jnt.com/DropF/droitwichplot2a.bmp
if the attachment doesn't get through


[image: DroitwichPlot2a.bmp]
Andy
www.g4jnt.com




Virus-free.
www.avg.com

<#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>

On Fri, 15 Jan 2021 at 21:55, Gilles Clement  
wrote:



Hi JF,
DCF77 is more distant, less powerful and probably more polluted 
(77kHz).

Anyhow I would probably not be able to measure better than 10e-11 with
current setup (need a better reference)
Indeed a good and stable phase lock was not easy to reach.
I experienced the day and night huge differences (as documented in 
post)

but nothing specific to phase shifts during sunrise or sunset.
No big difficulties with the ferrite antenna and the receiver design
either (thanks to good stuff from the old radio days probably).
Found that magnetic field antenna (ie: ferrite) appeared much less
sensitive to pollution than electric field antennas.
Naturally bad experience with Led bulbs and vapor gas lamps. You have 
to
chase them all and change to old filament lamps in and around the lab. 
No

issues with computers though.
What I found most challenging (and hence interesting) was the 
following :

- Temperature control, high resolution and high stability (Crystal
oscillator but also for the controller parts, ADC, DAC… )
- PI loop stability (very tricky)
- Matching theory with practice (still work in progress…!)
- Understanding the logic and physics behind behaviors, the real root
cause of problems,
and especially why a « really clever » enhancement - more than often -
actually leads to… performance degradation...
Gilles.



> Le 15 janv. 2021 à 16:57, JF PICARD via time-nuts <
time-nuts@lists.febo.com> a écrit :
>
> Hi,
> 800Kw according to the press release of ANFR. I doubt it is the best
choice : DCF77 is more precise (active hydrogen maser) but a little 
bit

more distant...
> But the phase lock of a quartz on a VLF signal is not as easy. There is
a considerable phase shift in the evening and in the morning with the 
sun

position, big instabilities at these moments and you have a hudge
difference between day and night (10 e-9/8)... Have a look at the 
Adret

receiver 4101 with its step motor phase lock...The engineering of the
ferrite road antenna is very tricky : temperature coefficient of the
ferrite, subtle tiny out of resonnace tuning, problem of the 
interferences
from domestic electrnic pollution (computers with sync of monitors, 
led

drivers...). The archiyecture of the receiver is also tricky : no AGC
(introduces phaseshift), heavy filtering (where : antenna, 
receiver...)

> On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement <
clemg...@gmail.com> wrote:
>
> Hi,
>
> This is to share current results on a "Long Wave RadioFrequency
Standard" project I have been pursuing for a while.
> Attached are typical ADEV plots and a block diagram of the system.
>
> I live in a crowded city (Paris, France) with no - or very limited -
access to open sky. Not good for GPS.
> However a long wave broadcasting public service is (still) available,
broadcasting time signal for clocks.
> The transmitter is located in Allouis, central France (200km for Paris).
> The signal is quite powerful (1MW) and the carrier (162kHz ) is
stabilized with a Cesium-standard.
>
> I decided to test how far I could go in disciplining a local VCO with
this signal.
>
> As well known, long wave RF has interesting features:
> - Signal is available (almost) everywhere, anytime, in the country
especially inside buildings (even underground !)
> - Quite stable and strong ground wave in day time.
> - Relatively easy antenna and RF signal processing (ferrite rod)
> And there are naturally a number of drawbacks (especially with the
Allouis signal) such as:
> - Much more unstable signal at night (interferences with ionospheric
path)
> - Large phase modulation of the carrier (time signals bits +/- 1 rad
phase modulated).
> - RF perturbations on the signal path.
> -Stop broadcasting for maintenance every Tuesday morning….
>
> Design of the « LWRFDO » was derived and inspired from many references
(including this list naturally).
> Principles are summarized in the attached pdf, with the following
specific feature to get rid of the phase modulation:
> The incoming signal 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Gilles Clement]

Hi JF, 
DCF77 is more distant, less powerful and probably more polluted (77kHz). 
Anyhow I would probably not be able to measure better than 10e-11 with current 
setup (need a better reference)
Indeed a good and stable phase lock was not easy to reach.
I experienced the day and night huge differences (as documented in post) but 
nothing specific to phase shifts during sunrise or sunset.
No big difficulties with the ferrite antenna and the receiver design either 
(thanks to good stuff from the old radio days probably). 
Found that magnetic field antenna (ie: ferrite) appeared much less sensitive to 
pollution than electric field antennas. 
Naturally bad experience with Led bulbs and vapor gas lamps. You have to chase 
them all and change to old filament lamps in and around the lab. No issues with 
computers though. 
What I found most challenging (and hence interesting) was the following : 
- Temperature control, high resolution and high stability (Crystal oscillator 
but also for the controller parts, ADC, DAC… )
- PI loop stability (very tricky)
- Matching theory with practice (still work in progress…!)
- Understanding the logic and physics behind behaviors, the real root cause of 
problems, 
and especially why a « really clever » enhancement - more than often - actually 
leads to… performance degradation...
Gilles. 



> Le 15 janv. 2021 à 16:57, JF PICARD via time-nuts  
> a écrit :
> 
> Hi,
> 800Kw according to the press release of ANFR. I doubt it is the best choice : 
> DCF77 is more precise (active hydrogen maser) but a little bit more 
> distant... 
> But the phase lock of a quartz on a VLF signal is not as easy. There is a 
> considerable phase shift in the evening and in the morning with the sun 
> position, big instabilities at these moments and you have a hudge difference 
> between day and night (10 e-9/8)... Have a look at the Adret receiver 4101 
> with its step motor phase lock...The engineering of the ferrite road antenna 
> is very tricky : temperature coefficient of the ferrite, subtle tiny out of 
> resonnace tuning, problem of the interferences from domestic electrnic 
> pollution (computers with sync of monitors, led drivers...). The archiyecture 
> of the receiver is also tricky : no AGC (introduces phaseshift), heavy 
> filtering (where : antenna, receiver...)
> On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement 
>  wrote:  
> 
> Hi, 
> 
> This is to share current results on a "Long Wave RadioFrequency Standard" 
> project I have been pursuing for a while.
> Attached are typical ADEV plots and a block diagram of the system. 
> 
> I live in a crowded city (Paris, France) with no - or very limited - access 
> to open sky. Not good for GPS.
> However a long wave broadcasting public service is (still) available, 
> broadcasting time signal for clocks.
> The transmitter is located in Allouis, central France (200km for Paris). 
> The signal is quite powerful (1MW) and the carrier (162kHz ) is stabilized 
> with a Cesium-standard. 
> 
> I decided to test how far I could go in disciplining a local VCO with this 
> signal. 
> 
> As well known, long wave RF has interesting features:
> - Signal is available (almost) everywhere, anytime, in the country especially 
> inside buildings (even underground !)
> - Quite stable and strong ground wave in day time.
> - Relatively easy antenna and RF signal processing (ferrite rod) 
> And there are naturally a number of drawbacks (especially with the Allouis 
> signal) such as: 
> - Much more unstable signal at night (interferences with ionospheric path)
> - Large phase modulation of the carrier (time signals bits +/- 1 rad phase 
> modulated).
> - RF perturbations on the signal path. 
> -Stop broadcasting for maintenance every Tuesday morning….
> 
> Design of the « LWRFDO » was derived and inspired from many references 
> (including this list naturally).
> Principles are summarized in the attached pdf, with the following specific 
> feature to get rid of the phase modulation: 
> The incoming signal has large sections of « un-modulated » segments between 
> the time signal bits.
> (Including a whole quiet section during the 59th second) 
> Such « quiet zones » are detected - where the 162kHz base carrier is 
> untouched - and measurement of phase difference
> with a local OCXO is then performed inside these quiet zones. Then PI 
> controller to a 20bits DAC (see picture).
> 
> Latest results show ADEV approaching 10E-11 at 1000 seconds on the « D2 » 
> graph (day time only).
> « DN123 » is a three days uninterrupted run, combining day and night signals, 
> showing the impact of night instabilities.
> The frequency standard stability at the transmitter site  is given for 10e-12.
> LWRFDO PPS is measured against an HP10811A PPS (about 10e-11 stability a 
> 100s) with a TICC, 
> So I believe 10-11 is not far from the best one could get. 
> Which is actually not too bad, isn’t it ?
> 
> Still working on improving the OCXCO (currently home 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[Bob kb8tq]

Hi

Very cool !!!

The red trace is obviously the one to focus on. Some sort of digital loop that
only operates under the “known good” conditions would seem to make sense. 

Thanks for sharing 

Bob

> On Jan 15, 2021, at 9:51 AM, Gilles Clement  wrote:
> 
> Hi, 
> 
> This is to share current results on a "Long Wave RadioFrequency Standard" 
> project I have been pursuing for a while.
> Attached are typical ADEV plots and a block diagram of the system. 
> 
> I live in a crowded city (Paris, France) with no - or very limited - access 
> to open sky. Not good for GPS.
> However a long wave broadcasting public service is (still) available, 
> broadcasting time signal for clocks.
> The transmitter is located in Allouis, central France (200km for Paris). 
> The signal is quite powerful (1MW) and the carrier (162kHz ) is stabilized 
> with a Cesium-standard. 
> 
> I decided to test how far I could go in disciplining a local VCO with this 
> signal. 
> 
> As well known, long wave RF has interesting features:
> - Signal is available (almost) everywhere, anytime, in the country especially 
> inside buildings (even underground !)
> - Quite stable and strong ground wave in day time.
> - Relatively easy antenna and RF signal processing (ferrite rod) 
> And there are naturally a number of drawbacks (especially with the Allouis 
> signal) such as: 
> - Much more unstable signal at night (interferences with ionospheric path)
> - Large phase modulation of the carrier (time signals bits +/- 1 rad phase 
> modulated).
> - RF perturbations on the signal path. 
> -Stop broadcasting for maintenance every Tuesday morning….
> 
> Design of the « LWRFDO » was derived and inspired from many references 
> (including this list naturally).
> Principles are summarized in the attached pdf, with the following specific 
> feature to get rid of the phase modulation: 
> The incoming signal has large sections of « un-modulated » segments between 
> the time signal bits.
> (Including a whole quiet section during the 59th second) 
> Such « quiet zones » are detected - where the 162kHz base carrier is 
> untouched - and measurement of phase difference
> with a local OCXO is then performed inside these quiet zones. Then PI 
> controller to a 20bits DAC (see picture).
> 
> Latest results show ADEV approaching 10E-11 at 1000 seconds on the « D2 » 
> graph (day time only).
> « DN123 » is a three days uninterrupted run, combining day and night signals, 
> showing the impact of night instabilities.
> The frequency standard stability at the transmitter site  is given for 10e-12.
> LWRFDO PPS is measured against an HP10811A PPS (about 10e-11 stability a 
> 100s) with a TICC, 
> So I believe 10-11 is not far from the best one could get. 
> Which is actually not too bad, isn’t it ?
> 
> Still working on improving the OCXCO (currently home brewed)
> 
> Comment and suggestions welcomed, 
> Gilles. 
> 
> <162kHz LWRFD0 bloc diagram.pdf>
> 
> 
> 
> 
> 
> 
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Re: [time-nuts] Long Wave Radio-Frequency standard testing

[paul swed]

I guess I would ask what the goal of the effort might be.
It seems like a good answer. One thing I was amazed buy was that back in
the 1960s HP wrote some papers on using WWVB. What they did was check the
offset at distance everyday about the same time. This offered quite a bit
more accuracy and avoided all of the night propagation effects. Essentially
from day to day the path is about the same.
If your system is stable enough could you simply put it in holdover at
night?
The other question I had is how do you then use the locked crystal
oscillator at 5.184 Mhz?
Does it somehow divide down to a useful number?
Nice project and good luck. Looking forward to hearing more.
Regards
Paul
WB8TSL

On Fri, Jan 15, 2021 at 11:02 AM JF PICARD via time-nuts <
time-nuts@lists.febo.com> wrote:

>  Hi,
> 800Kw according to the press release of ANFR. I doubt it is the best
> choice : DCF77 is more precise (active hydrogen maser) but a little bit
> more distant...
> But the phase lock of a quartz on a VLF signal is not as easy. There is a
> considerable phase shift in the evening and in the morning with the sun
> position, big instabilities at these moments and you have a hudge
> difference between day and night (10 e-9/8)... Have a look at the Adret
> receiver 4101 with its step motor phase lock...The engineering of the
> ferrite road antenna is very tricky : temperature coefficient of the
> ferrite, subtle tiny out of resonnace tuning, problem of the interferences
> from domestic electrnic pollution (computers with sync of monitors, led
> drivers...). The archiyecture of the receiver is also tricky : no AGC
> (introduces phaseshift), heavy filtering (where : antenna, receiver...)
>  On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement <
> clemg...@gmail.com> wrote:
>
>  Hi,
>
> This is to share current results on a "Long Wave RadioFrequency Standard"
> project I have been pursuing for a while.
> Attached are typical ADEV plots and a block diagram of the system.
>
> I live in a crowded city (Paris, France) with no - or very limited -
> access to open sky. Not good for GPS.
> However a long wave broadcasting public service is (still) available,
> broadcasting time signal for clocks.
> The transmitter is located in Allouis, central France (200km for Paris).
> The signal is quite powerful (1MW) and the carrier (162kHz ) is stabilized
> with a Cesium-standard.
>
> I decided to test how far I could go in disciplining a local VCO with this
> signal.
>
> As well known, long wave RF has interesting features:
> - Signal is available (almost) everywhere, anytime, in the country
> especially inside buildings (even underground !)
> - Quite stable and strong ground wave in day time.
> - Relatively easy antenna and RF signal processing (ferrite rod)
> And there are naturally a number of drawbacks (especially with the Allouis
> signal) such as:
> - Much more unstable signal at night (interferences with ionospheric path)
> - Large phase modulation of the carrier (time signals bits +/- 1 rad phase
> modulated).
> - RF perturbations on the signal path.
>  -Stop broadcasting for maintenance every Tuesday morning….
>
> Design of the « LWRFDO » was derived and inspired from many references
> (including this list naturally).
> Principles are summarized in the attached pdf, with the following specific
> feature to get rid of the phase modulation:
> The incoming signal has large sections of « un-modulated » segments
> between the time signal bits.
> (Including a whole quiet section during the 59th second)
> Such « quiet zones » are detected - where the 162kHz base carrier is
> untouched - and measurement of phase difference
> with a local OCXO is then performed inside these quiet zones. Then PI
> controller to a 20bits DAC (see picture).
>
> Latest results show ADEV approaching 10E-11 at 1000 seconds on the « D2 »
> graph (day time only).
> « DN123 » is a three days uninterrupted run, combining day and night
> signals, showing the impact of night instabilities.
> The frequency standard stability at the transmitter site  is given for
> 10e-12.
> LWRFDO PPS is measured against an HP10811A PPS (about 10e-11 stability a
> 100s) with a TICC,
> So I believe 10-11 is not far from the best one could get.
> Which is actually not too bad, isn’t it ?
>
> Still working on improving the OCXCO (currently home brewed)
>
> Comment and suggestions welcomed,
> Gilles.
>
>
>
>
>
>
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
> ___
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> and follow the instructions there.
>
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To 

Re: [time-nuts] Long Wave Radio-Frequency standard testing

[JF PICARD via time-nuts]

 Hi,
800Kw according to the press release of ANFR. I doubt it is the best choice : 
DCF77 is more precise (active hydrogen maser) but a little bit more distant... 
But the phase lock of a quartz on a VLF signal is not as easy. There is a 
considerable phase shift in the evening and in the morning with the sun 
position, big instabilities at these moments and you have a hudge difference 
between day and night (10 e-9/8)... Have a look at the Adret receiver 4101 with 
its step motor phase lock...The engineering of the ferrite road antenna is very 
tricky : temperature coefficient of the ferrite, subtle tiny out of resonnace 
tuning, problem of the interferences from domestic electrnic pollution 
(computers with sync of monitors, led drivers...). The archiyecture of the 
receiver is also tricky : no AGC (introduces phaseshift), heavy filtering 
(where : antenna, receiver...)
 On Friday, January 15, 2021, 03:54:40 PM GMT+1, Gilles Clement 
 wrote:  
 
 Hi, 

This is to share current results on a "Long Wave RadioFrequency Standard" 
project I have been pursuing for a while.
Attached are typical ADEV plots and a block diagram of the system. 

I live in a crowded city (Paris, France) with no - or very limited - access to 
open sky. Not good for GPS.
However a long wave broadcasting public service is (still) available, 
broadcasting time signal for clocks.
The transmitter is located in Allouis, central France (200km for Paris). 
The signal is quite powerful (1MW) and the carrier (162kHz ) is stabilized with 
a Cesium-standard. 

I decided to test how far I could go in disciplining a local VCO with this 
signal. 

As well known, long wave RF has interesting features:
- Signal is available (almost) everywhere, anytime, in the country especially 
inside buildings (even underground !)
- Quite stable and strong ground wave in day time.
- Relatively easy antenna and RF signal processing (ferrite rod) 
And there are naturally a number of drawbacks (especially with the Allouis 
signal) such as: 
- Much more unstable signal at night (interferences with ionospheric path)
- Large phase modulation of the carrier (time signals bits +/- 1 rad phase 
modulated).
- RF perturbations on the signal path. 
 -Stop broadcasting for maintenance every Tuesday morning….

Design of the « LWRFDO » was derived and inspired from many references 
(including this list naturally).
Principles are summarized in the attached pdf, with the following specific 
feature to get rid of the phase modulation: 
The incoming signal has large sections of « un-modulated » segments between the 
time signal bits.
(Including a whole quiet section during the 59th second) 
Such « quiet zones » are detected - where the 162kHz base carrier is untouched 
- and measurement of phase difference
with a local OCXO is then performed inside these quiet zones. Then PI 
controller to a 20bits DAC (see picture).

Latest results show ADEV approaching 10E-11 at 1000 seconds on the « D2 » graph 
(day time only).
« DN123 » is a three days uninterrupted run, combining day and night signals, 
showing the impact of night instabilities.
The frequency standard stability at the transmitter site  is given for 10e-12.
LWRFDO PPS is measured against an HP10811A PPS (about 10e-11 stability a 100s) 
with a TICC, 
So I believe 10-11 is not far from the best one could get. 
Which is actually not too bad, isn’t it ?

Still working on improving the OCXCO (currently home brewed)

Comment and suggestions welcomed, 
Gilles. 

 

 




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