Linear-phase digital anti-aliasing filter

A simple drift-free linear phase anti-aliasing filter is described which can be readily implemented in both hardware and software. Since the filter has equally weighted coefficients, it is well suited to microprocessor applications, especially if the value of N (number of equally weighted samples) is chosen to be of the form 2 to the P power, where P is a positive integer. Using a three-stage filter with R 0.1 (R cutoff frequency/sampling frequency), it is possible to achieve an attenuation greater than 50 dB at all aliasing frequencies using only 2 x 32 words of store.