Computationally Efficient Bank of Rectangular Digital Filters

A computationally efficient scheme for forming a bank of identical contiguous rectangular digital filters is described. The data processing is organized in a sequential form allowing use of the FFT algorithm as the first stage. An example is given in which a bank of 256 rectangular filters is formed using only a few percent of the number of complex multiplies required by straightforward procedures. The steepness of cutoff is unaltered and the inband ripple is only slightly affected, but the sidelobe level suffers some degradation.