[time-nuts] new WWVB BPSK dev board

[Poul-Henning Kamp]

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In message <20181204222100.293dc3259cf1d8683daeccdf at kinali.ch>, Attila Kinali writes:

>BPSK by itself does not improve timing. At most it improves reception
>by having a constant power envelope. But in case of WWVB, where
>the AM modulation is still kept, this is not the case. The phase
>changes do not help reception at all. In order to help reception,
>one needs to send a _known_ bit string in order for a corrolator
>in the receiver to pick the signal out of the noise. 

They do that in the "long" sequence, read their spec.

The fact that it is one out of 100-some known sequences does not
significantly change that situation.

And the BPSK does improve timing.

If you have access to, and tracks the carrier, you can nail the
timing all the way down to 1/your_sample_rate.

Been there, done that with DCF77 no big deal.

Even the weird phase-modulation of RDF and BBC on 198kHz can be
nailed down very precisely that way.

But the crucial thing is:  You need to digitize the carrier.

-- 
Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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