Empathy List Archives

GC

Gilles Clement

Sun, Mar 5, 2017 10:54 AM

Hi all,

I have been working for a "while"… on a reference oscillator disciplined by an RF signal (162khz), Cs stabilized, but phase modulated with time coding information. The phase modulation is quite significant : +/-1rad 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). Extracting the base signal was quite an interesting challenge… I tried many options (and even a bit more…) but it was - and is still - fun...

Long story short, the "best" combination I came up with is the following:
1- local oscillator built around: CD4060 Collpits + 5184Khz crystal + pulled by varactor diode + divide by 32
2- Phase detection with 4046 (XOR) with pp ouput voltage limited to 1 volt (input to 10bits ADC)
3- Filtering and VCO controlling with a PIC16F876, programmed in assembly language, implementing a 3rd order loop (much better than second order). Poles at 1E-5 and 1E-3, Zero at 1E-4 => 1E-10 attenuation at 10Hz (if my maths are correct).
4- 13 bits 20Khz PWM control of the VCO (K0=10-3 Hz/volt) with strong filtering (two RCs in cascade)
5- Crystal is temp controlled (NTC resistor) as well as the whole circuits placed in a foam isolated box.
6- ADEV measurements perfomed with HP53132A counter (high stability option 10 ocxo HP10811) frequency input to TIMELAB through HPIB connection (I know it's not the best setup but simple and provides tool for comparison between trials)

Results to date :
. « Left side » of the ADEV 0.5s: pretty flat around 1E-9 up to tau =10s
. « right side » of ADEV 0.5s plots: reaching 3*1E-11 at tau = 3000s

Comment:
6,3Hz/162kHz = 4E-5 so attenuation of 1E10 should knock it down to 4E-15 (well below 1E-11) ?

My questions to the respected audience:

Can I get any better?
Have I reached the limit of what the RF signal can provide?
(with all the perturbations encountered on the path from the transmitter to my antenna...)
Am I limited by the local oscillator?
Or the measurement gear?
Or anything else…?

Thanks very much for your feedback,

Gilles.

Note: 1E-3 = 0.001

Hi all, I have been working for a "while"… on a reference oscillator disciplined by an RF signal (162khz), Cs stabilized, but phase modulated with time coding information. The phase modulation is quite significant : +/-1rad 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). Extracting the base signal was quite an interesting challenge… I tried many options (and even a bit more…) but it was - and is still - fun... Long story short, the "best" combination I came up with is the following: 1- local oscillator built around: CD4060 Collpits + 5184Khz crystal + pulled by varactor diode + divide by 32 2- Phase detection with 4046 (XOR) with pp ouput voltage limited to 1 volt (input to 10bits ADC) 3- Filtering and VCO controlling with a PIC16F876, programmed in assembly language, implementing a 3rd order loop (much better than second order). Poles at 1E-5 and 1E-3, Zero at 1E-4 => 1E-10 attenuation at 10Hz (if my maths are correct). 4- 13 bits 20Khz PWM control of the VCO (K0=10-3 Hz/volt) with strong filtering (two RCs in cascade) 5- Crystal is temp controlled (NTC resistor) as well as the whole circuits placed in a foam isolated box. 6- ADEV measurements perfomed with HP53132A counter (high stability option 10 ocxo HP10811) frequency input to TIMELAB through HPIB connection (I know it's not the best setup but simple and provides tool for comparison between trials) Results to date : . « Left side » of the ADEV 0.5s: pretty flat around 1E-9 up to tau =10s . « right side » of ADEV 0.5s plots: reaching 3*1E-11 at tau = 3000s Comment: 6,3Hz/162kHz = 4E-5 so attenuation of 1E10 should knock it down to 4E-15 (well below 1E-11) ? My questions to the respected audience: - Can I get any better? - Have I reached the limit of what the RF signal can provide? (with all the perturbations encountered on the path from the transmitter to my antenna...) - Am I limited by the local oscillator? - Or the measurement gear? - Or anything else…? Thanks very much for your feedback, Gilles. Note: 1E-3 = 0.001

D

David

Sun, Mar 5, 2017 4:35 PM

If the modulation is phased locked to the carrier which is common,
then that suggests two other ways to extract the timing from the
carrier without interference from the modulation.

Integrate the phase comparison over a whole number of modulation
cycles; the modulation will then cancel out. This could be seen as
using a sin(x)/x frequency response with the nulls aligned to remove
just the modulation components of the signal.
Gate the phase comparison for periods where the modulation is not
occurring.

On Sun, 5 Mar 2017 11:54:56 +0100, you wrote:

I have been working for a "while" on a reference oscillator disciplined by an RF signal (162khz), Cs stabilized, but phase modulated with time coding information. The phase modulation is quite significant : +/-1rad 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). Extracting the base signal was quite an interesting challenge I tried many options (and even a bit more) but it was - and is still - fun...

...

My questions to the respected audience:

Can I get any better?
Have I reached the limit of what the RF signal can provide?
(with all the perturbations encountered on the path from the transmitter to my antenna...)
Am I limited by the local oscillator?
Or the measurement gear?
Or anything else?

Thanks very much for your feedback,

Gilles.

If the modulation is phased locked to the carrier which is common, then that suggests two other ways to extract the timing from the carrier without interference from the modulation. 1. Integrate the phase comparison over a whole number of modulation cycles; the modulation will then cancel out. This could be seen as using a sin(x)/x frequency response with the nulls aligned to remove just the modulation components of the signal. 2. Gate the phase comparison for periods where the modulation is not occurring. On Sun, 5 Mar 2017 11:54:56 +0100, you wrote: >I have been working for a "while" on a reference oscillator disciplined by an RF signal (162khz), Cs stabilized, but phase modulated with time coding information. The phase modulation is quite significant : +/-1rad 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). Extracting the base signal was quite an interesting challenge I tried many options (and even a bit more) but it was - and is still - fun... > >... > >My questions to the respected audience: >- Can I get any better? >- Have I reached the limit of what the RF signal can provide? >(with all the perturbations encountered on the path from the transmitter to my antenna...) >- Am I limited by the local oscillator? >- Or the measurement gear? >- Or anything else? > >Thanks very much for your feedback, > >Gilles.

PS

paul swed

Sun, Mar 5, 2017 8:23 PM

Gilles what signal is that at 162KHz. A European station? Nice thats its C
controlled.
Regards
Paul
WB8TSL

On Sun, Mar 5, 2017 at 5:54 AM, Gilles Clement clemgill@club-internet.fr
wrote:

Hi all,

I have been working for a "while"… on a reference oscillator disciplined
by an RF signal (162khz), Cs stabilized, but phase modulated with time
coding information. The phase modulation is quite significant : +/-1rad
10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz).
Extracting the base signal was quite an interesting challenge… I tried many
options (and even a bit more…) but it was - and is still - fun...

Long story short, the "best" combination I came up with is the following:
1- local oscillator built around: CD4060 Collpits + 5184Khz crystal +
pulled by varactor diode + divide by 32
2- Phase detection with 4046 (XOR) with pp ouput voltage limited to 1 volt
(input to 10bits ADC)
3- Filtering and VCO controlling with a PIC16F876, programmed in assembly
language, implementing a 3rd order loop (much better than second order).
Poles at 1E-5 and 1E-3, Zero at 1E-4 => 1E-10 attenuation at 10Hz (if my
maths are correct).
4- 13 bits 20Khz PWM control of the VCO (K0=10-3 Hz/volt) with strong
filtering (two RCs in cascade)
5- Crystal is temp controlled (NTC resistor) as well as the whole circuits
placed in a foam isolated box.
6- ADEV measurements perfomed with HP53132A counter (high stability option
10 ocxo HP10811) frequency input to TIMELAB through HPIB connection (I
know it's not the best setup but simple and provides tool for comparison
between trials)

Results to date :
. « Left side » of the ADEV 0.5s: pretty flat around 1E-9 up to
tau =10s
. « right side » of ADEV 0.5s plots: reaching 3*1E-11 at tau =
3000s

Comment:
6,3Hz/162kHz = 4E-5 so attenuation of 1E10 should knock it down to 4E-15
(well below 1E-11) ?

My questions to the respected audience:

Can I get any better?
Have I reached the limit of what the RF signal can provide?
(with all the perturbations encountered on the path from the transmitter
to my antenna...)
Am I limited by the local oscillator?
Or the measurement gear?
Or anything else…?

Thanks very much for your feedback,

Gilles.

Note: 1E-3 = 0.001

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

Gilles what signal is that at 162KHz. A European station? Nice thats its C controlled. Regards Paul WB8TSL On Sun, Mar 5, 2017 at 5:54 AM, Gilles Clement <clemgill@club-internet.fr> wrote: > Hi all, > > I have been working for a "while"… on a reference oscillator disciplined > by an RF signal (162khz), Cs stabilized, but phase modulated with time > coding information. The phase modulation is quite significant : +/-1rad > 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). > Extracting the base signal was quite an interesting challenge… I tried many > options (and even a bit more…) but it was - and is still - fun... > > Long story short, the "best" combination I came up with is the following: > 1- local oscillator built around: CD4060 Collpits + 5184Khz crystal + > pulled by varactor diode + divide by 32 > 2- Phase detection with 4046 (XOR) with pp ouput voltage limited to 1 volt > (input to 10bits ADC) > 3- Filtering and VCO controlling with a PIC16F876, programmed in assembly > language, implementing a 3rd order loop (much better than second order). > Poles at 1E-5 and 1E-3, Zero at 1E-4 => 1E-10 attenuation at 10Hz (if my > maths are correct). > 4- 13 bits 20Khz PWM control of the VCO (K0=10-3 Hz/volt) with strong > filtering (two RCs in cascade) > 5- Crystal is temp controlled (NTC resistor) as well as the whole circuits > placed in a foam isolated box. > 6- ADEV measurements perfomed with HP53132A counter (high stability option > 10 ocxo HP10811) frequency input to TIMELAB through HPIB connection (I > know it's not the best setup but simple and provides tool for comparison > between trials) > > Results to date : > . « Left side » of the ADEV 0.5s: pretty flat around 1E-9 up to > tau =10s > . « right side » of ADEV 0.5s plots: reaching 3*1E-11 at tau = > 3000s > > Comment: > 6,3Hz/162kHz = 4E-5 so attenuation of 1E10 should knock it down to 4E-15 > (well below 1E-11) ? > > My questions to the respected audience: > - Can I get any better? > - Have I reached the limit of what the RF signal can provide? > (with all the perturbations encountered on the path from the transmitter > to my antenna...) > - Am I limited by the local oscillator? > - Or the measurement gear? > - Or anything else…? > > Thanks very much for your feedback, > > Gilles. > > Note: 1E-3 = 0.001 > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

PS

paul swed

Sun, Mar 5, 2017 9:32 PM

Gilles I should have mentioned.
I use eLoran at 100 KHz in the US and am 400 miles from the transmitter.
Measuring Cesium references I typically run down in the 5 e-12th.
I see various noise at that level that says thats about the limit without
some smarter filtering, tracking and plotting.
The comparison units are austron 2100 series. The Cesium's are HP5061A's.
Very interested in what you are doing.
Regards
Paul
WB8TSL

On Sun, Mar 5, 2017 at 11:35 AM, David davidwhess@gmail.com wrote:

If the modulation is phased locked to the carrier which is common,
then that suggests two other ways to extract the timing from the
carrier without interference from the modulation.

Integrate the phase comparison over a whole number of modulation
cycles; the modulation will then cancel out. This could be seen as
using a sin(x)/x frequency response with the nulls aligned to remove
just the modulation components of the signal.
Gate the phase comparison for periods where the modulation is not
occurring.

On Sun, 5 Mar 2017 11:54:56 +0100, you wrote:

I have been working for a "while"… on a reference oscillator disciplined

by an RF signal (162khz), Cs stabilized, but phase modulated with time
coding information. The phase modulation is quite significant : +/-1rad
10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz).
Extracting the base signal was quite an interesting challenge… I tried many
options (and even a bit more…) but it was - and is still - fun...

...

My questions to the respected audience:

Can I get any better?
Have I reached the limit of what the RF signal can provide?
(with all the perturbations encountered on the path from the transmitter

to my antenna...)

Am I limited by the local oscillator?
Or the measurement gear?
Or anything else…?

Thanks very much for your feedback,

Gilles.

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

Gilles I should have mentioned. I use eLoran at 100 KHz in the US and am 400 miles from the transmitter. Measuring Cesium references I typically run down in the 5 e-12th. I see various noise at that level that says thats about the limit without some smarter filtering, tracking and plotting. The comparison units are austron 2100 series. The Cesium's are HP5061A's. Very interested in what you are doing. Regards Paul WB8TSL On Sun, Mar 5, 2017 at 11:35 AM, David <davidwhess@gmail.com> wrote: > If the modulation is phased locked to the carrier which is common, > then that suggests two other ways to extract the timing from the > carrier without interference from the modulation. > > 1. Integrate the phase comparison over a whole number of modulation > cycles; the modulation will then cancel out. This could be seen as > using a sin(x)/x frequency response with the nulls aligned to remove > just the modulation components of the signal. > > 2. Gate the phase comparison for periods where the modulation is not > occurring. > > On Sun, 5 Mar 2017 11:54:56 +0100, you wrote: > > >I have been working for a "while"… on a reference oscillator disciplined > by an RF signal (162khz), Cs stabilized, but phase modulated with time > coding information. The phase modulation is quite significant : +/-1rad > 10Hz triangular shape, leading to a frequency shift of +/- 20PI (+/-6,3Hz). > Extracting the base signal was quite an interesting challenge… I tried many > options (and even a bit more…) but it was - and is still - fun... > > > >... > > > >My questions to the respected audience: > >- Can I get any better? > >- Have I reached the limit of what the RF signal can provide? > >(with all the perturbations encountered on the path from the transmitter > to my antenna...) > >- Am I limited by the local oscillator? > >- Or the measurement gear? > >- Or anything else…? > > > >Thanks very much for your feedback, > > > >Gilles. > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

IY

Iain Young

Sun, Mar 5, 2017 10:42 PM

On 05/03/17 20:23, paul swed wrote:

Gilles what signal is that at 162KHz. A European station? Nice thats its C
controlled.

That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
the AM Station France Inter as well, but that went when France turned
off all LW, MW, and LORAN stations at the end of 2016.

The Time Signal is Phase Modulated (I have a gnuradio decoder which
works very well if anyone is interested)

See https://en.wikipedia.org/wiki/TDF_time_signal and
https://en.wikipedia.org/wiki/Allouis_longwave_transmitter

With no AM modulation, there are obvious benefits with regards to using
it as a frequency reference. Average phase and frequency deviation is
zero over 200msec (see link above for details)

Iain

PS, The signal is used by the French railways SNCF, the electricity
distributor ENEDIS, airports, hospitals according to the Allouis link
above

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

GC

Gilles Clement

Mon, Mar 6, 2017 2:23 AM

Hi,
Indeed, the station is located in central France with a very powerful transmitter (up to 2MW).
It covers all Europe and it was a real pain for me when they stopped broadcasting the France Inter Station.
The longwave signal can be received anywhere, even in the basements (ground effect propagation).
No need for an external full sky antenna etc…
Hopefully they are still operating and sending the time code.
And actually the signal is much clearer today in 2017 than when it was also amplitude modulated.
Good news, but how long will it last ... ?
Best,
Gilles.

Le 5 mars 2017 à 23:42, Iain Young iain@g7iii.net a écrit :

On 05/03/17 20:23, paul swed wrote:

Gilles what signal is that at 162KHz. A European station? Nice thats its C
controlled.

That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
the AM Station France Inter as well, but that went when France turned
off all LW, MW, and LORAN stations at the end of 2016.

The Time Signal is Phase Modulated (I have a gnuradio decoder which
works very well if anyone is interested)

See https://en.wikipedia.org/wiki/TDF_time_signal and
https://en.wikipedia.org/wiki/Allouis_longwave_transmitter

With no AM modulation, there are obvious benefits with regards to using
it as a frequency reference. Average phase and frequency deviation is
zero over 200msec (see link above for details)

Iain

PS, The signal is used by the French railways SNCF, the electricity
distributor ENEDIS, airports, hospitals according to the Allouis link
above

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

Hi, Indeed, the station is located in central France with a very powerful transmitter (up to 2MW). It covers all Europe and it was a real pain for me when they stopped broadcasting the France Inter Station. The longwave signal can be received anywhere, even in the basements (ground effect propagation). No need for an external full sky antenna etc… Hopefully they are still operating and sending the time code. And actually the signal is much clearer today in 2017 than when it was also amplitude modulated. Good news, but how long will it last ... ? Best, Gilles. > Le 5 mars 2017 à 23:42, Iain Young <iain@g7iii.net> a écrit : > > On 05/03/17 20:23, paul swed wrote: > >> Gilles what signal is that at 162KHz. A European station? Nice thats its C >> controlled. > > That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry > the AM Station France Inter as well, but that went when France turned > off all LW, MW, and LORAN stations at the end of 2016. > > The Time Signal is Phase Modulated (I have a gnuradio decoder which > works very well if anyone is interested) > > See https://en.wikipedia.org/wiki/TDF_time_signal and > https://en.wikipedia.org/wiki/Allouis_longwave_transmitter > > With no AM modulation, there are obvious benefits with regards to using > it as a frequency reference. Average phase and frequency deviation is > zero over 200msec (see link above for details) > > > Iain > > PS, The signal is used by the French railways SNCF, the electricity > distributor ENEDIS, airports, hospitals according to the Allouis link > above > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

BC

Bob Camp

Mon, Mar 6, 2017 7:26 AM

Hi

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

Bob

On Mar 5, 2017, at 11:42 PM, Iain Young iain@g7iii.net wrote:

On 05/03/17 20:23, paul swed wrote:

Gilles what signal is that at 162KHz. A European station? Nice thats its C
controlled.

That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
the AM Station France Inter as well, but that went when France turned
off all LW, MW, and LORAN stations at the end of 2016.

The Time Signal is Phase Modulated (I have a gnuradio decoder which
works very well if anyone is interested)

See https://en.wikipedia.org/wiki/TDF_time_signal and
https://en.wikipedia.org/wiki/Allouis_longwave_transmitter

With no AM modulation, there are obvious benefits with regards to using
it as a frequency reference. Average phase and frequency deviation is
zero over 200msec (see link above for details)

Iain

PS, The signal is used by the French railways SNCF, the electricity
distributor ENEDIS, airports, hospitals according to the Allouis link
above

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

Hi One way to “cheat” at recovering a time signal is to demodulate it with known information. Once you know the information from the first “frame” of data (time, date, etc) you can predict what the information in the next frame will be. Yes it does take a little work. If the signal is completely defined (no extra data about the weather forecast or something like that) you can reduce your bandwidth significantly. Bob > On Mar 5, 2017, at 11:42 PM, Iain Young <iain@g7iii.net> wrote: > > On 05/03/17 20:23, paul swed wrote: > >> Gilles what signal is that at 162KHz. A European station? Nice thats its C >> controlled. > > That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry > the AM Station France Inter as well, but that went when France turned > off all LW, MW, and LORAN stations at the end of 2016. > > The Time Signal is Phase Modulated (I have a gnuradio decoder which > works very well if anyone is interested) > > See https://en.wikipedia.org/wiki/TDF_time_signal and > https://en.wikipedia.org/wiki/Allouis_longwave_transmitter > > With no AM modulation, there are obvious benefits with regards to using > it as a frequency reference. Average phase and frequency deviation is > zero over 200msec (see link above for details) > > > Iain > > PS, The signal is used by the French railways SNCF, the electricity > distributor ENEDIS, airports, hospitals according to the Allouis link > above > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there.

IY

Iain Young

Mon, Mar 6, 2017 7:40 AM

Hi Gilles,

You Wrote:

Indeed, the station is located in central France with a very powerful transmitter (up to 2MW).
It covers all Europe and it was a real pain for me when they stopped broadcasting the France Inter Station.

I understand the French government have a consultation out about what
to use the AM carrier for, so maybe another commercial AM station will
pick it up.

The longwave signal can be received anywhere, even in the basements (ground effect propagation).
No need for an external full sky antenna etc…
Hopefully they are still operating and sending the time code.

They are. I've written an SDR decoder for it, and with it being Phase
Modulated, it doesn't suffer from the varying signal strengths of both
MSF and DCF.

And actually the signal is much clearer today in 2017 than when it was also amplitude modulated.
Good news, but how long will it last ... ?

Agreed, it's a nice clean carrier now :) I think it will last a good
time, Certainly with some of the things that use it in France, I
suspect it will be there for some time to come

Best Regards

Iain

Hi Gilles, You Wrote: > Indeed, the station is located in central France with a very powerful transmitter (up to 2MW). > It covers all Europe and it was a real pain for me when they stopped broadcasting the France Inter Station. I understand the French government have a consultation out about what to use the AM carrier for, so maybe another commercial AM station will pick it up. > The longwave signal can be received anywhere, even in the basements (ground effect propagation). > No need for an external full sky antenna etc… > Hopefully they are still operating and sending the time code. They are. I've written an SDR decoder for it, and with it being Phase Modulated, it doesn't suffer from the varying signal strengths of both MSF and DCF. > And actually the signal is much clearer today in 2017 than when it was also amplitude modulated. > Good news, but how long will it last ... ? Agreed, it's a nice clean carrier now :) I think it will last a good time, Certainly with some of the things that use it in France, I suspect it will be there for some time to come Best Regards Iain

AW

Anders Wallin

Mon, Mar 6, 2017 9:57 AM

FWIW, for fun I measured the LF stations MSF, DCF, and TDF just a few days
ago. The signals look like this from our site:
http://www.anderswallin.net/wp-content/uploads/2017/02/MSF.jpg
http://www.anderswallin.net/wp-content/uploads/2017/02/DCF.jpg
http://www.anderswallin.net/wp-content/uploads/2017/02/TDF.jpg

I guess the +/- 40 Hz side-bands on TDF are by design?

I have an SDR set up also, so the gnu-radio demodulators could run in
parallel on each of these, and the sdr sampling clock could come from a
local clock. One more project on the to-do list...

Anders

On Mon, Mar 6, 2017 at 12:42 AM, Iain Young iain@g7iii.net wrote:

On 05/03/17 20:23, paul swed wrote:

Gilles what signal is that at 162KHz. A European station? Nice thats its C

controlled.

That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
the AM Station France Inter as well, but that went when France turned
off all LW, MW, and LORAN stations at the end of 2016.

The Time Signal is Phase Modulated (I have a gnuradio decoder which
works very well if anyone is interested)

See https://en.wikipedia.org/wiki/TDF_time_signal and
https://en.wikipedia.org/wiki/Allouis_longwave_transmitter

With no AM modulation, there are obvious benefits with regards to using
it as a frequency reference. Average phase and frequency deviation is
zero over 200msec (see link above for details)

Iain

PS, The signal is used by the French railways SNCF, the electricity
distributor ENEDIS, airports, hospitals according to the Allouis link
above

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

FWIW, for fun I measured the LF stations MSF, DCF, and TDF just a few days ago. The signals look like this from our site: http://www.anderswallin.net/wp-content/uploads/2017/02/MSF.jpg http://www.anderswallin.net/wp-content/uploads/2017/02/DCF.jpg http://www.anderswallin.net/wp-content/uploads/2017/02/TDF.jpg I guess the +/- 40 Hz side-bands on TDF are by design? I have an SDR set up also, so the gnu-radio demodulators could run in parallel on each of these, and the sdr sampling clock could come from a local clock. One more project on the to-do list... Anders On Mon, Mar 6, 2017 at 12:42 AM, Iain Young <iain@g7iii.net> wrote: > On 05/03/17 20:23, paul swed wrote: > > Gilles what signal is that at 162KHz. A European station? Nice thats its C >> controlled. >> > > That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry > the AM Station France Inter as well, but that went when France turned > off all LW, MW, and LORAN stations at the end of 2016. > > The Time Signal is Phase Modulated (I have a gnuradio decoder which > works very well if anyone is interested) > > See https://en.wikipedia.org/wiki/TDF_time_signal and > https://en.wikipedia.org/wiki/Allouis_longwave_transmitter > > With no AM modulation, there are obvious benefits with regards to using > it as a frequency reference. Average phase and frequency deviation is > zero over 200msec (see link above for details) > > > Iain > > PS, The signal is used by the French railways SNCF, the electricity > distributor ENEDIS, airports, hospitals according to the Allouis link > above > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/m > ailman/listinfo/time-nuts > and follow the instructions there. >

PS

paul swed

Mon, Mar 6, 2017 2:23 PM

Gilles,
I just looked at the signal behavior from the TDFlink you sent.There are 14
seconds worth of very controlled phase. There are additional bits also.
As Bob says if the format is controlled you can predict the change and
correct the phase. This is exactly what I created for the wwvb BPSK signal
in the US about 1-2 years ago. It runs on a small arduino and requires no
modification to any of the phase tracking receivers. It super simple with
few parts. It was my first arduino project and took maybe a week of time at
night.

Granted I like the rest of the work you are doing and the prediction
concept can very reasonably be put into you software for prediction.
You should not need to worry about a unpredictable phase flip. On wwvb
there are a couple bits that can not be predicted but never seen that yet.
Even if they do a 3-4 second loop constant like all of the old receivers
has removes the issue.

Plan to warm up the HP3586 tonight and take a listen at 162 KHz in the US.
Regards
Paul
WB8TSL

On Mon, Mar 6, 2017 at 4:57 AM, Anders Wallin anders.e.e.wallin@gmail.com
wrote:

FWIW, for fun I measured the LF stations MSF, DCF, and TDF just a few days
ago. The signals look like this from our site:
http://www.anderswallin.net/wp-content/uploads/2017/02/MSF.jpg
http://www.anderswallin.net/wp-content/uploads/2017/02/DCF.jpg
http://www.anderswallin.net/wp-content/uploads/2017/02/TDF.jpg

I guess the +/- 40 Hz side-bands on TDF are by design?

I have an SDR set up also, so the gnu-radio demodulators could run in
parallel on each of these, and the sdr sampling clock could come from a
local clock. One more project on the to-do list...

Anders

On Mon, Mar 6, 2017 at 12:42 AM, Iain Young iain@g7iii.net wrote:

On 05/03/17 20:23, paul swed wrote:

Gilles what signal is that at 162KHz. A European station? Nice thats its

C

controlled.

That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry
the AM Station France Inter as well, but that went when France turned
off all LW, MW, and LORAN stations at the end of 2016.

The Time Signal is Phase Modulated (I have a gnuradio decoder which
works very well if anyone is interested)

See https://en.wikipedia.org/wiki/TDF_time_signal and
https://en.wikipedia.org/wiki/Allouis_longwave_transmitter

With no AM modulation, there are obvious benefits with regards to using
it as a frequency reference. Average phase and frequency deviation is
zero over 200msec (see link above for details)

Iain

PS, The signal is used by the French railways SNCF, the electricity
distributor ENEDIS, airports, hospitals according to the Allouis link
above

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

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

Gilles, I just looked at the signal behavior from the TDFlink you sent.There are 14 seconds worth of very controlled phase. There are additional bits also. As Bob says if the format is controlled you can predict the change and correct the phase. This is exactly what I created for the wwvb BPSK signal in the US about 1-2 years ago. It runs on a small arduino and requires no modification to any of the phase tracking receivers. It super simple with few parts. It was my first arduino project and took maybe a week of time at night. Granted I like the rest of the work you are doing and the prediction concept can very reasonably be put into you software for prediction. You should not need to worry about a unpredictable phase flip. On wwvb there are a couple bits that can not be predicted but never seen that yet. Even if they do a 3-4 second loop constant like all of the old receivers has removes the issue. Plan to warm up the HP3586 tonight and take a listen at 162 KHz in the US. Regards Paul WB8TSL On Mon, Mar 6, 2017 at 4:57 AM, Anders Wallin <anders.e.e.wallin@gmail.com> wrote: > FWIW, for fun I measured the LF stations MSF, DCF, and TDF just a few days > ago. The signals look like this from our site: > http://www.anderswallin.net/wp-content/uploads/2017/02/MSF.jpg > http://www.anderswallin.net/wp-content/uploads/2017/02/DCF.jpg > http://www.anderswallin.net/wp-content/uploads/2017/02/TDF.jpg > > I guess the +/- 40 Hz side-bands on TDF are by design? > > I have an SDR set up also, so the gnu-radio demodulators could run in > parallel on each of these, and the sdr sampling clock could come from a > local clock. One more project on the to-do list... > > Anders > > > On Mon, Mar 6, 2017 at 12:42 AM, Iain Young <iain@g7iii.net> wrote: > > > On 05/03/17 20:23, paul swed wrote: > > > > Gilles what signal is that at 162KHz. A European station? Nice thats its > C > >> controlled. > >> > > > > That's TDF from France. Their equivalent of WWV/MSF/DCF. Used to carry > > the AM Station France Inter as well, but that went when France turned > > off all LW, MW, and LORAN stations at the end of 2016. > > > > The Time Signal is Phase Modulated (I have a gnuradio decoder which > > works very well if anyone is interested) > > > > See https://en.wikipedia.org/wiki/TDF_time_signal and > > https://en.wikipedia.org/wiki/Allouis_longwave_transmitter > > > > With no AM modulation, there are obvious benefits with regards to using > > it as a frequency reference. Average phase and frequency deviation is > > zero over 200msec (see link above for details) > > > > > > Iain > > > > PS, The signal is used by the French railways SNCF, the electricity > > distributor ENEDIS, airports, hospitals according to the Allouis link > > above > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to https://www.febo.com/cgi-bin/m > > ailman/listinfo/time-nuts > > and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to https://www.febo.com/cgi-bin/ > mailman/listinfo/time-nuts > and follow the instructions there. >

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