Sampling rate

1. Nyquist sampling rate must be at least twice of the maximum frequency of the input signal in order to perfectly recover the signal.

2. To avoid aliasing, the signal should be passed through a low-pass filter before sampling.

3. In practice, sampling rates should be 1.2 times the Nyquist rate to allow for the filter transition band.

Reference from the book entitled "Elements of wavelets for engineers and scientists" by Dwight F. Mix and Kraig J. Olejniczak, 2003.