Notes on Digital Signal Processing: Practical Recipes for Design, Analysis and Implementation

Note 16. Exploring DFT Resolution

This note provides demonstrations of a technique called zero padding, which is often used to obtain a finer frequency-domain increment when using a discrete Fourier transform (DFT). These demonstrations show that although zero padding improves the observability of some frequency domain features, it does not improve the frequency resolution of a DFT.

Sometimes important features of a signal’s spectrum fall at frequencies between the DFT bin frequencies, making potentially important features of a signal’s spectrum difficult to detect or observe. This inability to see critical details that fall at frequencies that are not integer multiples of F = NT – 1 is sometimes called the picket fence effect because it is ...