To compute an FIR filter coefficient having a fine SN ratio and response characteristic based on a set frequency characteristic.

An individual phase information generating part 22 computes a real part and an imaginary part of a spectrum power on a frequency axis based on: an absolute value of the spectrum power on the frequency axis based on a frequency response coefficient on the frequency axis read out from a user setting coefficient memory 30 storing the frequency response coefficient on the frequency axis; and a function value of a given phase function of specifying a phase on the frequency axis. An overall phase information-generating part 23 refers to a coefficient on a time base obtained by a Fourier inverse transformation of the real part and imaginary part of the spectrum power on the frequency axis, and specifies a predetermined forefront position on the time base which should be a forefront of the FIR filter coefficient. A coefficient sequence change part 25 rearranges the coefficients based on the predetermined forefront position on the time base, and uses the rearranged coefficients as the FIR filter coefficients to store them in an FIR filter coefficient memory 31.

COPYRIGHT: (C)2010,JPO&INPIT