Wednesday, December 30, 2009

Nyquist sampling theorem

To avoid aliasing, the sampling rate should be greater than twice the highest frequency present in the signal. fs >= 2*f

In frequency domain. If the sample rate (fs) is less than 2*f, aliasing will happen.


In time domain: From following example, the sampling waveform has aliasing.

In following example, there is a white dot in the wheel. Assume a 24 fps film recording the wheel. When 24 < 2*13Hz, the wheel looks like it is going backward. 


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