Hi That works fine if you are doing things manual to check a local standard. If you are trying to disipline a few thousand cell towers 24 hours a day … not so much. It also works for checking frequency. What modern systems need is time. That gets you into a whole world of resolving and identifying individual edges. The WWVB signal really was never set up for this. Loran-C is an example of a signal that was designed to identify a specific edge.
Bob > On Aug 31, 2018, at 10:30 AM, Martin VE3OAT <ve3...@storm.ca> wrote: > > But the diurnal phase shifts at VLF are predictable and largely repeatable. > Ignore the phase at night and use only the phase records during the day when > an all-daylight propagation path exists. You might have to "correct" the > absolute phase reading by some multiple of the RF period, but with a low rate > of local standard oscillator drift, this is a simple matter of arithmetic. > Back in the day, I managed Sulzer crystal oscillators at 5 field sites from > my office and could maintain phase continuity for weeks at a time, until we > had to diddle the dial on one or several of them to correct for crystal > aging. Then it was just more arithmetic again. Several of the oscillators > had such low drift rates that all I needed was one daily phase reading from > the VLF phase tracking receiver (Tracor 599Js) at those sites to know the > frequency of the Sulzers there. > > ... Martin VE3OAT > > On Thu, 30 Aug 2018 12:27:12 -0400 > Bob kb8tq<kb...@n1k.org> wrote: > >> WWVB as transmitted ( = right at the input to the antenna) is a wonderfully >> stable signal. As soon as >> that signal hits the real world things start to degrade. Propagation between >> transmit and receive sites >> is a big deal, even at 60 KHz. On top of that, there is a*lot* of manmade >> noise at 60 KHz. The receive >> signal to noise will never be as good as you might like it to be ?. > > > I don't know about WWVB, but for DCF77 it's known that sunrise/sunset >> causes a phase shift of several 100?s at even moderate distances >> (like ~500km). Unfortunately I don't have any measurements at hand. >> Attila Kinali > > > _______________________________________________ > 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. _______________________________________________ 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.
