Design of efficient digital filters satisfying arbitrary loss and delay specifications

Designing recursive digital filters satisfying both arbitrary loss and delay constraints is a classical problem. There is no known general analytical solution that can yield coefficient values. Many techniques have been proposed that offer various advantages, and some of these are reviewed in the paper. If, in addition, the particular application requires a high sampling rate, as in, for example, video and sonar systems, then it is important that the structure is efficient in the sense of a minimum number of arithmetic operations for a given order. Furthermore, in some sonar applications, there is a further requirement for bandpass and multiple bandpass filters. To this end, a filter structure made up from a parallel arrangement of two allpass subfilters is considered in the paper. Such structures were used originally in multi-rate problems but have also been applied to conventional filtering. A new approach to design is presented that uses a dual-line template in conjunction with simulated annealing, which gives a finite wordlength solution directly. The authors conclude with several detailed design examples showing the efficacy of the proposed technique