Theory: Sampling Theorem & Nyquist Frequency [closed]

Question

i've got a problem with the sampling theorem

Sampling theorem states that a signal can be reconstructed exactly from it's samples if the original signal has no frequencies above half the sampling frequency.

But what about frequencies exactly half the sampling frequency?? let's say i sample a sine (with an arbitrary phase and amplitude) with a frequency exactly double the sine frequency. I will be unable to reconstruct the phase and the amplitude of the sine because i don't know how the phase shifted the sine in relation to my samples (for example, if i happen to sample exactly on the zero-crossings of the sine, my samples will all be zero).

what's the solution to that problem?

Answer 1

Check this: http://en.wikipedia.org/wiki/Nyquist_rate#Nyquist_rate_relative_to_sampling It's clearly stated that the sampling rate should exceed the Nyquist rate, which is double the highest frequency component.