Gary wrote:
I know all of the Rick.
It still does not explain how you can digitize a signal with amplitude that
is 140 dB signal above one LSB using a 16 bit A to D.
------------------------------------
This is not how it works.
The gain is NOT adjusted to make the weakest signal strong enough to toggle
the LSB. It's adjusted to keep the strongest signal from saturating the
A/D. Our signal that is down in the lower 10db of that 140db range come out
in the processing. IIRC increasing the sample rate by four allows enough
averaging of noise to increase the effective dynamic range by 1bit.
A 192kHz 16bit sound card is effectively the same as a 48kHz 17bit.
or a 12kHz - 18bit
or a 3kHz - 19bit
and so on.
If our SDR is sampling 16 bit at 400MHz ...
There are even tricks if there is not enough noise to average out, we can
add some in. the IC 7300 can do this. Useful on VHF/UHF and maybe on a
quiet 10 or 15 but you'll never need it on the lower bands.
-Bob
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