Band-pass filter for frequency modulated signal transmission

A band-pass filter for frequency-modulated signal transmission comprising a delay circuit comprising a plurality of unit delay elements connected in cascade arrangement and receiving as input a signal containing a frequency-modulated signal, and a coefficient summing circuit for carrying out coefficient summing of outputs produced by specific delay elements of said delay circuit and producing as output said frequency modulated signal in band-pass filtered state, said band-pass filter having a transmission characteristic represented substantially by the equation

• H(j.omega.) = [ 1 - a(.omega. - .omega.o).sup.2 ] e.sup..sup.-j.sup..omega..sup..tau.d,
• where:
• a is a constant for imparting the attenuation characteristic of the filter;
• .omega.o is the angular frequency of the carrier wave of the frequency-modulated signal and the center angular frequency of the band-pass filter;
• and
• .tau. d is the delay time of the band-pass filter.