Digital filter system

A digital filter system which can vary at least one of a position and a width of a pass band thereof, comprising:

• a digital filter for filtering an input digital signal in accordance with a filter coefficient FC.sub.h (h=1, 2, . . . , n;
• n is a natural number), and for outputting the filtered signal;
• calculation means for calculating the filter coefficient FC.sub.h in accordance with equation (56) with pass band position data x and pass band width data y;
• and
• setting means for setting the filter coefficient FC.sub.h calculated by said calculation means, to said digital filter;
• ##EQU15## "L" and "M" are orders, and S.sub.hi and T.sub.hj are predetermined constants.

A digital filter system comprising:

• a digital filter for filtering an input digital signal in accordance with filter coefficients, and for outputting the filtered signal;
• parameter storage means for storing parameters for calculating said filter coefficients which are defined by a non-linear polynomial for a position and/or a width for a pass band of said digital filter;
• filter coefficient calculation means for calculating the filter coefficients, based on the parameters stored in said parameter storage means, and the position and/or width of the pass band of said digital filter;
• and
• setting means for setting the filter coefficients calculated by said filter coefficient calculation means to said digital filter.