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.
CHAPTER
FFT Convolution
18

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