[time-nuts] RFDO - Experience and questions

Pieter-Tjerk de Boer ptdeboer at cs.utwente.nl
Mon Mar 6 13:46:24 EST 2017


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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