[time-nuts] WWVB and spectracom 8170 receivers etc

[paul swed]

Good morning to the group.
I did not think that FEBO would be operating.
I wanted to respond to the 8170 discussion that had been running but typing
on itty bitty screens is tough.
So now that I am on a real keyboard I can do a better job.
The discussion actually went a bit askew in the fact that evidently some
8170s lock to the new wwvb BPSK signal.
But here is the facts. Cheap AM demodulated receivers will and do work.
These do not use phase tracking for data recovery.
Any phase tracking receiver can not work with the new format. This includes
spectracoms, HP, Tracors, Fluke, and True-time. There may be others, I have
them all accept the true-time. This is stated by spectracom and NIST and
understanding the new modulation scheme it makes sense why they don't work.
So the very real question isn't why are many of our 8170s not working. Its
why some 8170s do work apparently without modification?
As I think about this its the perfect time-nuts enigma.

On time-nuts there have been several comments on squaring techniques and if
you are just looking for time recover for an 8170 that is a simple solution
that should work. You do not need long term system stability to recover the
time. However if frequency/phase recovery is your interest this approach is
quite poor requiring very favorable propagation with consistant very high
signal levels.
Some of us time-nuts have those conditions. Most don't.
I seriously went through the easy squaring methods. They all work per
theory on the bench but totally fail in real world 60 Khz reception due to
the following reasons. (I am east coast with 60uv day signal levels)
Impulse noise, Amplitude modulation, and propagation dynamics. One missed
cycle and the output phase flips. On the charts you end up with essentially
noise. Oh how I wanted those approaches to work. Simple, easy, cheap.

So thats where I am at. Why would any timing receiver that uses phase
recovery actually work to recover time (Phase is out). Something to be
learned here, but I have no way to actually figure it out. I have had my
8170 on for 30 min and no lock. It used to lock in about 1-2 min before the
signal changed. I tested this during the transition period and it
consistently failed.

Looking forward to the knowledge this group has to answering that question.
Does any math support a receiver thats off frequency to recover the time
signal. I might guess that there is and that the 8170s that happen to work
do so by this method.
Hey if it makes the 8170 work I will offset the oscillator. Heck thats an
easy fix.
Regards
Paul
WB8TSL