[time-nuts] WWVB a different approach to d-bpsk-r (cheating)

paul swed paulswedb at gmail.com
Sat Jul 14 19:50:56 UTC 2012


OK have been doing a lot of experimenting.
I was curious what is the GPS tick in relationship to wwvb. Especially
since it is a reliable 1 sec marker.
Using a Tbolt since everyone has one on the list. ;-) And monitoring the 10
us tick to the wwvb 60 Khz carrier on a scope. Amazingly and over at least
2 hours now, the rising cycle of 60 Khz aligns to the 10 us Tbolt tick
rising edge. Expected some form of drift.

Would not have actually thought there should be such a relationship or its
truly pot luck today.
WWVB today is also not running bpsk.

Should such a relationship actually exist?
There is a clue in a 1985 article in ham radio magazine.
It went something like this. At any given instant the 60 Khz may jitter.
But for every 1 sec period there will be exactly 60,000 cycles.

If it does stay aligned, then the cheating d-bpsk-r gets to be interesting
and very implementable.

The approach using a micro to sample a squared up 60 Khz after the Tbolt
tic.
Perform 2-3 1 usec samples in the leading 90 degree signal.
Decide is it a 0 or 1 phase.
Select a inverted or non inverted 60 Khz into the output path to maintain a
constant phase 60 Khz for the old recvrs.

Sure its cheating. But if this relationship is real I should be able to
implement the answer very quickly as a proof point.

Have not heard if the NIST testing is completed or when the next one is.
But for today all of the rcvrs are working just fine.
Regards
Paul
WB8TSL



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