| 摘要 |
PURPOSE:To realize a calculation for apporximating the amplitude characteristic with high accuracy at high speed by converting a cut-off frequency and a maximum frequency in a digital region into a correction frequency subject to correction of distortion by bilinear s-z conversion, a correction transfer function whose amplitude characteristic is coincident with an analog region transfer function, and applying the bilinear s-z conversion to the function so as to obtain a digital region transfer function. CONSTITUTION:A cut-off frequency and a maximum frequency in a digital region are converted into a correction frequency subject to correction of distortion by bilinear s-z conversion respectively, and a correction transfer function whose amplitude characteristic is coincident with an analog region transfer function at the correction frequency is obtained. The correction transfer function is converted into a digital region transfer function by the bilinear s-z conversion. A digital filter having the said transfer function is easily realized by adjusting coefficients of multipliers 2 - 5,8,9. Thus, the amplitude characteristic of the transfer function in the analog region is approximated with high accuracy from a low frequency region to a high frequency region and the transfer function in the digital region is calculated at high speed. |
