| Summary: | 碩士 === 國立高雄大學 === 電機工程學系碩士班 === 102 === Conventionally, variable fractional-delay finite-impulse-response digital filters are generally by minimizing the root-mean-square error of variable frequency response. In this paper, a new criterion concerning the minimization of the root-mean-square error of variable group-delay response is proposed. However, minimization is a highly nonlinear problem, so an iterative method is proposed in this paper to overcome it. To further reduce the maximum absolute group-delay error in the least squares design, an iterative weighting-updated technique is also proposed. In this paper, a new approach is proposed for the design of infinite-impulse-response comb filter. The problem of the comb filter design is transformed into that of fractional delay filter design. Using the proposed method, the multiplier inside the proposed structure can be fixed regardless the value of fundamental frequency of harmonic interferences. This improvement makes the proposed structure be possible for the design of variable cases. To realize variable comb filter, the variable fractional-delay filter is designed in weighted least-squares. Then, by embedding the designed variable-fractional-delay filter with a switch, the variable comb filter could be implemented in a proposed structure.
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