Hi Let’s see…. WWV (not WWVB) gets here via a variety of propagation mechanisms that vary over the day. According to NIST (who probably know :) that puts a random timing variation of ~1 ms on the signal. Since some modes get me a signal and others don’t, there is no real reason to assume it is random. It can easily be an offset that varies month to month.
Net result, forget about the chip delays. The signal already has a bunch of built in variability that will swamp anything in the silicon. https://www.nist.gov/pml/time-and-frequency-division/nist-radio-broadcasts-frequently-asked-questions-faq Also in the same data is the fact that the “as transmitted” signal is good to 100 ns. That’s plenty good enough for the system as described. It also is a pretty modest number for a GPS timing module. One would guess that the number is a bit better than 100 ns (it is NIST after all). It also does not directly compare to the GPS number since there are UTC offset numbers there as well. Bottom line is that there inevitably *are* numbers like that buried in the system once you get past the 1 ms. Bob > On Oct 29, 2016, at 1:36 AM, Nick Sayer via time-nuts <time-nuts@febo.com> > wrote: > > That single-chip version is going to have a *LOT* less (and less variable) > latency than an SDR. > >> On Oct 27, 2016, at 12:20 AM, Poul-Henning Kamp <p...@phk.freebsd.dk> wrote: >> >> -------- >> In message <5a002554-8d90-4c75-95da-21db45d61...@kfu.com>, Nick Sayer via >> time- >> nuts writes: >> >>> If you’re in North America, a CHU receiver is a lot easier to make >>> than WWV/WWVH. The CHU timecode is just BEL 103 AFSK at 300 baud - >>> it was a one-chip solution 20 years ago when I made one in college. >> >> We have CPUs and sounds-cards these days... >> >> Also: The KiwiSDR is nearly perfect hardware, no matter which VLF/HF >> station you want: You can track GPS and four (possibly 8) VLF/HF >> stations at the same time. >> >> -- >> 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. _______________________________________________ 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.
