[time-nuts] RFDO - Experience and questions

paul swed paulswedb at gmail.com
Mon Mar 6 22:35:26 EST 2017

Actually as I think about it from the earlier part of the thread. Locking
to the carrier with a 2-4 second time constant removes the phase modulation
since its only in the first 200 ms. The 0 Phase is 800 ms in length or more
for all bits.
Now to find some nice coils for 162 KHz.

On Mon, Mar 6, 2017 at 8:30 PM, paul swed <paulswedb at gmail.com> wrote:

> 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
> 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
>> 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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