Patent ID: 6286019
Filing Date: 2001-09-04
Classification: H03H

Abstract:
In a digital filter for filtering an input signal ""x"" to produce an output signal ""y"", wherein filtering occurs by taking n+1 samples of the input signal ""x"" to extract a number of input signal samples x(0) through x(n), wherein filtering also occurs using digital filter coefficients c(0) through c(n) corresponding to the input signal samples x(0) through x(n), respectively, a method for digitally filtering using sequential multiply and add instructions for increased filtering efficiency for microprocessors that use sequential multiply and add instructions, the method comprising:a step for loading a working value equal to a last input signal sample x(n);where ""m"" is an integer initially equaling ""n"", a step for multiplying the working value by a constant c(m)/c(m-1) to thereby alter the working value, wherein the constant c(m)/c(m-1) is equal to the quotient of a digital filter coefficient c(m) corresponding to an input signal sample x(m) divided by a digital filter coefficient c(m-1) corresponding to a previous input signal sample x(m-1);a step for adding the working value that resulted from the step for multiplying to the value of the previous input signal sample x(m-1) to thereby alter the working value; anda step for generating the output signal ""y"" based at least in part on the working value that resulted from the step for adding.