[time-nuts] WWVB BPSK Receiver Project?

[Chris Albertson]

The major advantage of simply sampling at 192K is that it is so
simple.  Not much hardware outside of a good audio interface is
required.

But the mixer is attractive because  then you can make it a quadrature
mixer and then sample with both stereo channels.   One then could use
a more common 44.1 or 48K sample rate.

You trade a bit of hardware up front for reduced processing
requirements later.


On Thu, Mar 15, 2012 at 12:38 AM, Peter Monta <pmonta at gmail.com> wrote:
>> Many A/D converter systems use a sample and hold before the A/D converter.
>> If you do the same before your sound card (your A/D converter) and drive the S&H with an audio output from your sound
>> card, say at 6.1 kHz you would get a 1 kHz signal into your sound card to process. You can call it under sampling
>> aliasing or whatever.
>
> Yes, this would work, but instantaneous sampling would tend to alias
> in many harmonics, requiring good prefiltering at RF (if you can call
> 60 kHz RF).  Just as easy would be a mixer from CMOS switches, driven
> say at 50 kHz to get 10 kHz into the sound card.
>
> The WWVB signal apparently has a double-sided bandwidth of about 1200
> Hz (not clear from the paper if that means 3 dB bandwidth or something
> else).  To get all of the signal something like 2 or 3 kHz might be
> safest, requiring an IF of several kHz at least.
>
> Cheers,
> Peter
>
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-- 

Chris Albertson
Redondo Beach, California