[time-nuts] RFDO - Experience and questions

paul swed paulswedb at gmail.com
Mon Mar 6 20:30:25 EST 2017


A bit more reading if you block the phase comparison from -50ms to 150ms of
the tick you get a 0 carrier phase no modulation. That also explains why I
thought I could here some sort of phase modulation because there is.
So as an example if you use a GPS tick its really simple to block the phase
changes and only measure the 0 phase carrier. Essentially a 200 ms carrier
gap per second.
Thats quite a clean format you have to work with.
Regards
Paul
WB8TSL


On Mon, Mar 6, 2017 at 8:19 PM, paul swed <paulswedb at gmail.com> wrote:

> I checked out 162KHz at 2000 local and now have what I believe to be TDF
> using the 67 ft vertical antenna. I am reading -82 dbm near Boston in the
> US or 3400 miles. A comfortable signal at least in the winter. As a
> comparison wwvb at 60 KHz is -77dbm some 2000 miles but also not at a 2 MW
> power level like TDF.
>
> Since I had not heard TDF before I listened to Pieters online SDR radio to
> see what to listen for. The easiest point to notice is the 59 second phase.
> Its funny that also seconds 0-10 should be the same phase but it did not
> seem to be true. Unless what I am hearing is the local oscillator of
> Pieters SDR radio.
>
> So thanks for sharing some new knowledge with Time-nuts.
> Regards
> Paul
> WB8TSL
>
> On Mon, Mar 6, 2017 at 1:46 PM, Pieter-Tjerk de Boer <
> ptdeboer at cs.utwente.nl> wrote:
>
>>
>> On Sun, Mar 05, 2017 at 10:42:52PM +0000, Iain Young wrote:
>>
>> > That's TDF from France. Their equivalent of WWV/MSF/DCF.
>>
>> > Average phase and frequency deviation is
>> > zero over 200msec (see link above for details)
>>
>> This is not quite correct, since the transmitter does not just carry the
>> time data (one bit per second, in the first 200 ms of the second), but
>> also some more data during the next 700 ms of each second.
>> The latter data is coded in a way which does not guarantee that the phase
>> or frequency average is zero other than when averaging over the entire
>> 700 ms block.
>> Then again, I've been told that although there is a nicely defined framing
>> format, in reality it has only ever transmitted idle frames, so in
>> practice
>> it's a fixed pattern which repeats every minute and thus could be
>> cancelled
>> for use as a frequency reference.
>>
>> I have a live online decoder for TDF's signal at
>>    http://websdr.ewi.utwente.nl:8901/tdf/
>>
>> Regards,
>>   Pieter-Tjerk, PA3FWM
>>
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