[time-nuts] WWVB BPSK Receiver Project?

Marek Peca marek at duch.cz
Thu Mar 15 10:58:49 UTC 2012


>  I know I am not one of the good-ole-boys here but I'd say go 100% SDR 
> with your PC without an external A/D converter. Ok, how would you do 
> this?  You use under sampling. 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.

Unfortunately, this works only with a few types of sound cards. Last 
several years, most of PC audio cards use sigma-delta ADCs and there is no 
way to get quality undersampling. Tried it. I can not tell there was no 
signal -- there were really some carriers mirrors, but on odd frequencies 
and largely attenuated.

Greetings,
Marek



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