[CST-2] IT&C Nyquist

[Inge Norum]

>> Ok, Nyquist Rate: minimum sample with twice highest frequency (in
>> Hertz) and that'll somehow work.
>> 
>> Example: y = sin x.
>> nyquist samples: x=0, pi, 2pi, 3pi, ...
>> 
>> thing is: all of these samples have the same value of y: zero. So you're
>> blatantly not going to be able to reconstruct the signal.
> 
> 
> You know the frequency W (1/(2pi) in this case).  There's only one function
> with a period of 2pi that has y=0 at at x=0, pi, ... - and that's y = sin x
> !  You're right that if you didn't know what W was, you'd be stuck - he
> didn't stress that you still need it in the lectures, but in the notes he's
> got the equation for reconstructing the original signal from the samples,
> and that uses W several times.

You would not know the amplitude. It could be 0..!

That a signal is band-limited by W means that its frequency spectra lies 
in the range -W < w < W. The highest frequency in the signal (1/(2pi)) 
must be (slightly) less than W. Sampling at 2W will then completely 
capture the signal. (if this is right?)