| 摘要 |
PURPOSE:To use a memory of low speed and low cost by dividing the sampling interval of an input sampling frequency to a finite number of sections and previously calculating coefficients corresponding to these sections. CONSTITUTION:Coefficient groups corresponding to respective sections into which the sampling interval of the input sampling frequency is divided are previously calculated and are stored in a coefficient memory 16. Plural sample values obtained with the input sampling frequency are inputted to the input terminal of a finite impulse response(FIR) filter 20 as a calculating means with an output sampling frequency. When the output sample value is moved to the next section, a coefficient controller 18 accesses the coefficient memory 16 to output another coefficient group for the FIR filter 20. Consequently, the number of coefficients of the filter is reduced when a ratio of input and output sampling frequencies approximates one. Thus, the memory of low speed and low cost is used as the coefficient memory. |
