-------- In message <cagj4f+54sxqc34fpnefnw3q3emhmq+uc-v-lfc5bnfk7h7q...@mail.gmail.com>, "Deirdre O'Byrne" writes:
>With a blame algorithm in place it should be possible to recover these signals. Yes, easily. At distance MSF is significantly harder to receive than DCF77. One of the reasons is that USA also operates two 60kHz transmitters also very precisely on frequency, so there are areas of the world where the three signals cancel and areas where they reinforce each other. I tried to model this many years ago, but I don't trust the result, somebody with better HF-propagation chops than me should look at it. In addition to that problem, switch-mode designers seems to just *love* 60 kHz, and at least here in Denmark there is a lot more "hash" around 60 kHz than 77.5 kHz. Finally, the modulation scheme of MSF is a bit on the overengineered side, which makes pulse discrimination needlessly hard - as you have also found out. The big advantage of the blame algorithm is that since it is so tolerant of missing pulses, you can be throw everything away which isn't 100% clearcut. If you look at the top of the dcf77.c file, you can see how I did that for DCF77, but the complex modulation of MSF needs a much more complex state engine there. Finally, many of the small "clock-receivers", like the one you use, are optimised for battery-life and therefore they use very resonant filters, often crystal-filters, and heavy low-pass after demodulation, and that trows away a LOT of information which would be useful to have to discriminate the pulses. If you go for the SDR approach, you will have much more information available, and can use much more well-behaved filters to detect the pulses, and one added advantage of carrier-tracking is that the power-modulation is carrier-synchronous, which makes them much easier to spot. So really: Get yourself an 1MSPS ADC chip and go that route instead. (In theory, certain modern sound-cards should be usable for this if you can rip out their low-pass filters. Havn't tried.) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.