Original poster: Ed Phillips <evp@xxxxxxxxxxx>
"So, perhaps you sampled at 22kHz, and there's this huge 30-50 kHz
signal out
there... it might just alias down and look like it's at a few kHz.
Providing a) it makes it through (or around) the usual low-pass
"anti-aliasing" (or roofing) filter in front of the a/d; and b) that the
aperture time on the A/D is small enough to actually sample it (rather
than
acting as a single pole low pass)."
Agreed, but how if you're looking at a record sampled at 11 kHz you do
you know which higher-order ambiguity you're dealing with, IF ANY? An
infinite number of sine waves can fit those sample points in exactly the
same way. As for intermod, I'm sure there could be plenty of that.
[Been working with "digital" radar receivers for many years and we never
have a high enough sampling rate or anywhere near enough bits to do what
we'd like.]
Ed