Improved Design of Frequency-Response Masking Filters Using Band-Edge Shaping Filter With Non-Periodical Frequency Response

Frequency-Response Masking (FRM) technique has been widely used in all kinds of applications where FIR filters with extremely narrow transition band are needed. Thus, researchers have invested much effort to find ways to increase the efficiency of the FRM algorithm. In this paper, a novel 2-stage FRM structure was proposed. The three interpolation factors of the subfilters in the second stage can be chosen independently. The band-edge shaping filter synthesized by the second stage has a non-periodical frequency response, which is quite different from conventional FRM structures. Various filters were designed to test the performance of the proposed method. Experiments show that the proposed structure achieves lower complexity, in terms of the number of multipliers, compared to the FRM algorithms such as 1-stage FRM, 2-stage FRM, IFIR-FRM, SFFM-FRM, serial-masking FRM and some current FRM structures.