On 7/19/2012 1:30 PM, Hal Murray wrote:
As long as you don't have sunset or sunrise between you and the transmitter,
WWVB is reasonably stable. At night you will get more signal, but also can
have some skywave "stuff" in the mix.
One man's noise is another man's signal.
The NIST coverage maps vary widely from night to day. I assume their night maps depend
upon skywave. So depending upon where you live, the "some skywave stuff" may
be very important.
Maybe fancy (rather than low cost) receivers work without (in spite of) the
skywave.
Hal
Life is never easy. I think wwvb should just connect a direct fibre to
anyone that wants it. I could get rid of the RBs and CS etc.
Oh well.
Yes indeed I see the effects you are speaking of.
So strangely during the day the gps tic lines up with a rising edge of
the cycle. Kind of amazing actually as I am in Boston.
At sunset and sunrise I do see at least a 7-10us shift and its variable.
But I don't think any of this matters a lot.
My logic is this wait for a gps tick or even a local tick
Is the wwvb a plus cycle or minus. If minus flip to plus
Can get all fancy then check a couple of cyles and make sure its plus or
minus then flip.
Also as diurnal shift occurs its usually slow enough that the system can
keep flipping as needed to keep the plus cycle aligned to the gps tick.
Lots of clever things can be done if the simple theory holds or is even
reasonable.
A subset of the approach is check if a + if not is it actually a minus
or zero a fade. Do nothing if a fade. All to familiar here.
So this is not at all hard to build program or test. Just have a few
distractions at hand.
Regards
Paul WB8TSL
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