An efficient approach to noncausal filtering

A new method for designing digital noncausal filters is introduced. The design is based on well developed analog filter approximations and their Wiener-Lee decomposition forms. The resulting filter is linear phase in the passband and suitable for sample-by-sample processing. Comparing with conventional two-pass noncausal recursive filters, the proposed filter has the advantages of a small basic group delay and a small memory size requirement. Moreover, the magnitude and phase responses are exactly known.