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

[Bob Camp]

Hi

The Costas loop already has the AM component available. There's no need for a second receiver, just wire the AM output over to the output modulator.

Bob

On Jun 17, 2013, at 5:57 PM, "David I. Emery" <die at dieconsulting.com> wrote:

> 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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