Frequency-response-masking technique incorporating extrapolated impulse response band-edge shaping filter

Techniques based on the frequency-response masking (FRM) approach are known to be highly efficient for achieving drastic reduction of the number of multipliers and adders in narrow transition band linear-phase finite-impulse response (FIR) filters. Basic FRM structure comprises a band-edge shaping filter and two masking filters. It is observed that the impulse response of the band-edge shaping filter of FRM shows quasi-periodic property. Previous study demonstrated that the quasi-periodic property of the impulse responses of lowpass or highpass digital FIR filters can be exploited to reduce the complexity of the filter by using extrapolated impulse response technique. Extrapolating the idea, the band-edge shaping filter in FRM may be designed by the extrapolated impulse response technique. In this paper, an FRM technique incorporating extrapolated impulse response band-edge shaping filter is introduced. An iterative optimization procedure is proposed to design the FRM subfilters. An example taken from the literature is used to illustrate that the number of multipliers produced by our technique is less than 80 percent of earlier results.