Unlimited impulse response forma digital filter

摘要

PURPOSE:To decrease minimum frequencies without enlarging the number of arithmetic bits by specifying the sampling frequencies of a recurrent type filter block. CONSTITUTION:By combining a delay element Z-1, a multiplier A and an adder B, filter blocks 1, 2 and 3 are composed. The blocks 1 and 3 are non-recurrent type filters, and the block 2 is the recurrent type filter. The sampling frequencies of the block 2 are set at 1/2n (n is a positive integer) of the sampling frequencies of the whole filter. Thus, the number of times of arithmetic operation is reduced to 1/2n, and an arithmetic word length is reduced by the (n) bit portion. Consequently, a limit cycle can be decreased without increasing the number of the arithmetic bits of the block 2.