| 摘要 |
PURPOSE:To designate the characteristic with nearly uniform interval logarithmically over a broad band by providing plural filter stages each consisting of a couple of digital filters having a band pass characteristic and a low pass characteristic respectively between input and output in parallel according to a prescribed rule and changing a unit delay time of a delay element for multiplex usage. CONSTITUTION:The delay time per one stage of delay element being a component of a digital filter, e.g., S4, of the band pass characteristic is selected as 1/f0.2<-4>sec. The output characteristic of the digital filter S4 is as shown in figure (a). In order to erase the odd number order pass band, a signal is inputted to a digital filter F4 having the low pass characteristic whose delay time per shift register stage is 1/f0.2<-3>sec via a delay circuit t4 and a weighting circuit b4. In figure (b) of the filter F4, the delay time per delay element stage is added to an output of a digital filter S3 whose band pass characteristic is 1/f0.2<-3>sec at an adder circuit D4 and the result is shown in figure (c). The similar processing is repeated and an output of an object characteristic is obtained from the final digital filter F0.
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