Frequency Sampling Method for FIR Filter Design

The frequency-sampling method for FIR filter design is perhaps the simplest and most direct technique imaginable when a desired frequency response has been specified.

• It consists simply of uniformly sampling the desired frequency response, and performing the inverse DFT to obtain the corresponding (finite) impulse response.
• The resulting frequency response is usually not optimal between samples
• When the desired frequency-response is undersampled (typical) the impulse response is time aliased
• It is important to compare the originally desired frequency response to the FFT of the zero-padded designed impulse response (simulated DTFT)