On Wed, Dec 05, 2018 at 08:23:59PM +0000, Poul-Henning Kamp wrote: > -------- > In message <d1e866d9-3a6e-472f-a780-61cb03de3...@club-internet.fr>, > Club-Intern > et Clemgill writes: > > >- One bit only is coded per second in each minute => 59 bits available > >because... > >- 59th second is silent (no phase modulation) > > I belive this is wrong. > > The timecode (substantially the same as DCF77) occupies only one > bit (the first) in each second, but more bits are encoded each > second after the first one, I belive for some kind of "telecontrol" > scheme.
Yes, that's correct. In the remaining part in each second, more bits are transmitted, using a more complex three-level modulation scheme, with a data packet format defined for it. However, it has never been used for actual user data (so I was told by someone from CFHM, the organisation behind this time signal). So effectively it is only transmitting idle frames, which boils down to a 1-minute-long ever repeating pseudo-random sequence. Being completely predictable, this sequence could be used to improve timing receiver accuracy. The Allouis signal can be seen live here: http://websdr.ewi.utwente.nl:8901/tdf/ And here's another, perhaps even more nutty, example of decoding the signal: http://www.pa3fwm.nl/signals/clock-lille-flandres/ Regards, Pieter-Tjerk, PA3FWM _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
