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

[paul swed]

Bob
Yes nights are bad for me, east coast and MSF interference.
So it could be any number of 60 KHz crossing its just odd it lined up the
way it did and I double confirmed that I was not doing something silly like
using alternate triggers.

Very careful analysis does show a 1-2 us jitter and at diurnal shift I
really expect something to change it has to.
Regards
Paul.

On Sat, Jul 14, 2012 at 4:32 PM, Bob Camp <lists at rtty.us> wrote:

> Hi
>
> The "zero crossing" is very arbitrary. If it's correct at the transmit
> site, it will then be off everywhere else by the speed of light / distance.
> You will appear to be correct  once every wavelength away from Colorado
> (roughly every 3 miles). You won't really be correct because you are
> looking at a different zero crossing.
>
> 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.
>
> Bob
>
> On Jul 14, 2012, at 3:50 PM, paul swed wrote:
>
> > 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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