[time-nuts] wtd: WWVB info

Hal Murray hmurray at megapathdsl.net
Fri Aug 7 04:40:27 EDT 2015


kb8tq at n1k.org said:
> Well, at least *some* of the chips out there do not make it to 96 KHz when
> sampling at 192 KHz. It’s  been a few years since I dug into them. Back then
> a chip that had an internal filter that went to 96K was very much the
> exception rather than the rule. If the only point of 192K is getting to a
> 96K bandwidth, a lot of the chip guys missed out on it …. 

Where did 192 KHz come from?  Why is anybody interested in anything that far 
over 2*44 KHz?

It's common to have an audio ADC run much faster than Nyquist, but that's a 
hack to make it easier to build the cut off filter.  You build a simple 
analog filter and a sharp digital filter and decimator so the output is 2x 
the target frequency.  You get what you want without a fancy analog filter.


-- 
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