[time-nuts] WWV and legal issues
kb8tq at n1k.org
Thu Aug 30 14:02:32 EDT 2018
Same basic problem with WWVB. If you were using it as a reference, you timed your
data collection to avoid the transition periods. You got both phase shifting and the
amplitude took a dive. Neither one was going to help you make a precision measurement.
In addition there are various weather events (terrestrial and solar) that can get into
the mix. You can see blips here and there that do not correlate with the sunrise / sunset
stuff. Again, not a big deal if you are manual evaluating the data to check your local
Rb standard or super duper OCXO. Not a good thing for disciplining a system 24 hours
a day 365 days a year.
> On Aug 30, 2018, at 1:54 PM, Attila Kinali <attila at kinali.ch> wrote:
> On Thu, 30 Aug 2018 12:27:12 -0400
> Bob kb8tq <kb8tq at 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 100µs at even moderate distances
> (like ~500km). Unfortunately I don't have any measurements at hand.
> Attila Kinali
> It is upon moral qualities that a society is ultimately founded. All
> the prosperity and technological sophistication in the world is of no
> use without that foundation.
> -- Miss Matheson, The Diamond Age, Neal Stephenson
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