[time-nuts] Spectracom 8170 grief... Watching the problem...

Tom Van Baak tvb at LeapSecond.com
Sat Jun 15 00:46:11 UTC 2013


> What I saw was the phase of the WWVB signal shifting back and forth 
> 180 Degrees coincident with the dips in the carrier. Coincidentally, 
> this is what all of you have been telling me, but, just the same, it 
> was interesting to watch. The duration of each shift obviously are a 
> form of zeros, ones and place holder. I'm wondering if the code used 
> to shift the phase is the same code as carried in the legacy system 
> where the duration of the carrier dips corresponds to the ones and 
> zeros, and the place holder.
> 
> Burt, K6OQK

The new PM (phase modulated) WWVB format is *in addition* to the existing AM format. Consequently millions of commodity clocks and wrist watches continue to function just fine. The only instruments that break are vintage phase tracking receivers. Paul's Costas's loop project addresses those receivers.

The latest preliminary version of the spec for the new PM code is here:
http://www.nist.gov/pml/div688/grp40/upload/NIST-Enhanced-WWVB-Broadcast-Format-2012-12-07-3.pdf

If anyone has seen a more recent version, let me know.

Thanks,
/tvb




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