1983 年 39 巻 4 号 p. 221-229
Different sampling frequencies have been recommended for different applications as digital audio technology is prevailing. An efficient sampling frequency converter has been required for a system which has to accomodate many units operating at different sampling frequencies. This paper describes the implementation of a practical sampling frequency converter using digital filters. In particular, the reduction of filter order is investigated for high fidelity transmission and practical hardware. Taking note that the order depends chiefly on transmission band width, the process of the order reduction is examined from a viewpoint of using the effective IIR filter and FIR filter combination. To obtain a good combination, a new 2nd order IIR filter is developed which has sharp cut-off response and approximately linear phase characteristic. The successful combination enables the filters to reduce its practical order(multiplication number)by1/3compared with conventional FIR filters. The converter incorporating the new filters is implemented by computer simulation. The computed results show that the converter is at satisfactory level of practical application, and has the advantages of high fidelity signal transmission and simplified circuits.