🚀 go-pugleaf

In article <D04gX2w163w@shark.cs.fau.edu> terryb.bbs@shark.cs.fau.edu (terry bohning) writes:
>north@manta.NOSC.MIL (Mark H. North) writes:
>
>> >     i.e. If you have a 60HZ sine wave, and you sample at 120HZ, you're
>> >only going to get two points per cycle.
>> 
>> And imagine that those two points are phased such that they land at the
>> zero crossing of the 60Hz signal. All your samples are zero! This is
>> why you must sample at greater than 2nu.
>> 
>The catch is that you *know* you're sampling the highest input freq at
>2 points per cycle.  That is, the input signal is bandlimited.  So if
>someone gives you a set of all zero samples and you know the sample
>rate is 120 Hz, the only frequency it can be is 60 Hz.
>The Nyquist theorem is at least, not greater than. Oppenheim & Schafer,
>"Digital Signal Processing", Prentice-Hall, 1975, pg. 28 bottom.
>In reality, of course, since ideal filters are unavailable for
>band-limiting, the rate must be higher.

I knew that 8^). Actually, I got to thinking about it since this discussion
came up and I believe I emailed someone mentioning the above possibility but
this would be as they say a trivial (and useless) case wouldn't you agree?

Mark