[time-nuts] WWVB remodulator for the Spectracom 8170...

David I. Emery die at dieconsulting.com
Mon Jun 17 21:57:50 UTC 2013


On Mon, Jun 17, 2013 at 02:41:13PM -0700, Burt I. Weiner wrote:
> Chris,
> 
> The 8170 was originally intended to be a frequency reference source 
> tied to the USFS (United Stated Frequency Standard).  It also gave 
> the time of day, but I believe that wasn't it's primary purpose.  As 
> I recall, there were some versions that did not have the clock 
> readout and some that had a chart recorder.  Back in the 80's I used 
> to drool (it was a disgusting sight!) over the Spectracom receivers 
> with the chart recorders.  At that time I was usuing a Gertsch RLF-1 
> with an external Moseley 680 chart recorder.  The remodulator 
> precludes it from being used as a frequency standard, but in my 
> opinion, so does the fact that WWVB is now phase shifted a bunch.
> 
> The 8170 uses a coherent detector and that's where the problem 
> lies.  While the 8170 still locks to the WWVB carrier, the new BPSK 
> scheme causes the detector to output bad data in spite of the 
> original dips in the carrier still being present.  I had always 
> wondered how it was able to pull the data out the noise, but never 
> had a manual until just recently.  I had naively assumed that the 
> WWVB new BPSK scheme would not affect the time of day aspect of the 
> 8170.  Like I said, I only use it as a clock in my shoppe, and being 
> an old dog I don't easily learn new tricks such as looking in a 
> different direction for one of the other clocks.

	I suppose I am stating the obvious, but why not combine Paul
Swed's Costas loop and this scheme to output a phase locked 60 Khz 
with the right AM modulation ?



-- 
  Dave Emery N1PRE/AE, die at dieconsulting.com  DIE Consulting, Weston, Mass 02493
"An empty zombie mind with a forlorn barely readable weatherbeaten
'For Rent' sign still vainly flapping outside on the weed encrusted pole - in 
celebration of what could have been, but wasn't and is not to be now either."




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