# How to determine Nyquist Rate

I have the Fourier Transform of a signal. How can I determine the Nyquist Rate of that signal? What is the formula for that?

• If you have fourier transform of a signal,then you will know the maximum frequency present in the signal. you can sample the signal at a frequency greater than twice the maximum frequency that you obtain from fourier transform. That will be your nyqvist rate. May 20 '14 at 4:39

## 1 Answer

For finite length or time limited signals, the Nyquist rate only makes sense given some finite noise floor requirement and finite total signal energy. You look for the frequency at or above which nothing is above that noise floor and the total remaining energy is below that noise floor. Twice that is the minimum sampling frequency to avoid aliasing causing any noise above that given floor.

For infinite length signals, there is the possibility of a frequency domain window of finite support width.