Re: [time-nuts] FS: Spectracom 8161 "Standard Frequency Receiver - Oscillator" for WWVB (and question...)

2020-10-04 Thread Kirk Bailey 
Magnus,

Thanks for the manual pointer!  A quick scan doesn't offer me much
insight to what the mod might be for (likely have to open it up as you
suggest).  The basic unit gives you the option of phase-locking the
internal standard osc to WWVB with an output at .1, 1, 5, or 10 MHz , and
you can compare either the internal or an external oscillator to WWVB and
chart the results over a variable time period.

Given the time-nuts mailing list audience my guess is that in practice
it would likely be used with an external reference source to monitor WWVB
deviations, instead of the other way around...

It was fun to see the effect of the "sun flares" noise on the sample
chart recordings in the manual!

Kirk Bailey
bai...@peak.org
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Re: [time-nuts] FS: Spectracom 8161 "Standard Frequency Receiver - Oscillator" for WWVB (and question...)

2020-10-04 Thread Magnus Danielson 
Hi,

I got a bit curious, so I dug up the manual (Available from Orolia that
Spectracom is part of):

https://www.orolia.com/sites/default/files/document-files/8161_manual.pdf

It is apparent that the reference oscillator is actually free-running
but compared to the WWVB, so you manually tune it to make the
strip-chart become more of a flat line.

This is interesting, because the receiver locks up another 10 MHz
oscillator.

Now, there is a 45 degree (2.1 micro) modulation on the WWVB signal,
that shows up as time-tags on the strip-chart, so it is not trivially so
that you just replace the simpler 10 MHz oscillator with the more
advanced, unless you can live with that modulation at which time it is a
fairlly trivial hack. You can be a bit more cunning to add hardware to
compensate the modulation, but I wonder if that is what is done.

To figure it out, one has to pop the lid to figure out. That is however
not for me to do.

Anyway, I thought the manual pointer and quick analysis would maybe be
appreciated.

Good luck!

Cheers,
Magnus

On 2020-10-04 09:37, Kirk Bailey wrote:
> I ran across an interesting widget in my ongoing "find the bottom of the
> pile" task.  Has a label indicating it was modified for "WWVB Continuous
> Monitored".  I thought these were all for WWVB, so what does "Continuous
> Monitored" mean?  See attached pic.  If anyone is interested in being the
> new owner please contact me directly.
>
> Thanks,
>
> Kirk Bailey
> bai...@peak.org
>
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