Zero Padding

Zero padding is a technique typically employed to make the size of the input sequence equal to a power of two. In zero padding, you add zeros to the end of the input sequence so that the total number of samples is equal to the next higher power of two. For example, if you have 10 samples of a signal, you can add six zeros to make the total number of samples equal to 16, or 32, which is a power of two. The following figure shows padding 10 samples of a signal with zeros to make the total number of samples equal 16.

The addition of zeros to the end of the time-domain waveform does not improve the underlying frequency resolution associated with the time-domain signal. The only way to improve the frequency resolution of the time-domain signal is to increase the acquisition time and acquire longer time records.

In addition to making the total number of samples a power of two so that faster computation is made possible by using the fast Fourier transform (FFT), zero padding can lead to an interpolated FFT result, which can produce a higher display resolution.