Posted by
David Woolley (E.L) on
Oct 16, 2007; 7:48am
URL: http://elecraft.85.s1.nabble.com/K3-15khz-2nd-IF-tp454741p454743.html
[hidden email] wrote:
> The lower you go, the better, because you get more samples per Hz of
> signal. (If you are sampling a 15 kHz signal 150,000 times per
> second, that's 10,000 samples per Hz, but if you were to sample a 150
> kHz signal the same number of times per second you only get 1000 > samples per Hz.) All else being equal, more samples per Hz is better, as
> is more bits per sample.
This doesn't make sense to me. In a quadrature system, you only need to
sample at a sampling *rate* equal to the bandwidth (you meet the Nyquist
condition because the I and Q samples effectively double the rate). In
practice you would want to sample based on the skirt bandwidth, not the
nose bandwidth.
I believe some DSP based receivers actually sample a band limited IF
directly, at the bandwidth dictated sampling rate.
Going low probably makes the whole process more reliable.
--
David Woolley
Emails are not formal business letters, whatever businesses may want.
RFC1855 says there should be an address here, but, in a world of spam,
that is no longer good advice, as archive address hiding may not work.
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