Digital Signal Processing: A Practical Guide for Engineers and Scientists

CHAPTER 18

FFT Convolution

This chapter presents two important DSP techniques, the overlap-add method, and FFT convolution. The overlap-add method is used to break long signals into smaller segments for easier processing. FFT convolution uses the overlap-add method together with the Fast Fourier Transform, allowing signals to be convolved by multiplying their frequency spectra. For filter kernels longer than about 64 points, FFT convolution is faster than standard convolution, while producing exactly the same result.

The Overlap-Add Method

There are many DSP applications where a long signal must be filtered in segments. For instance, high-fidelity digital audio requires a data rate of about 5 Mbytes/min, while digital video requires about ...