[time-nuts] RFDO - Experience and questions

paul swed paulswedb at gmail.com
Mon Mar 6 20:19:41 EST 2017

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.

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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