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Re: sample rate
I thought the Nyquist theorem is all about reconstructing a signal once sampled. A signal is not reconstructed by simply "connecting the dots", it is reconstructed by passing it through a low pass filter. If you pass a sawtooth, triangle, square, or any other variety of periodic signal with frequency f through a low pass filter whose passband is perfectly flat up until frequency f, and then perfectly 0 beyond f, then what comes out is a pure sine wave of frequency f - that's because squares, triangles and whatnot all contain harmonics in addition to the pure sine wave that dictates its fundamental frequency.
A signal sampled at twice the Nyquist frequency can be perfectly reconstructed in a world of perfect filters and perfect sampling devices.