Patent ID: 7502143

Claim:
A signal processing method for superposing a noise signal generated based on pseudo-random numbers on an input signal to generate an output signal, comprising the steps of: generating a predetermined number of pseudo-random numbers having different phases; executing a convolution operation with the generated pseudo-random numbers and coefficients determined by a desired frequency characteristic of the output signal; instructing the generating of the predetermined number of pseudo-random numbers having different phases to start generating and to stop generating; stopping the generation of the predetermined number of pseudo-random numbers for initialization, and setting the phase of a pseudo-random number to be different from the phase of another pseudo-random number during the initialization; and generating a noise signal to be superposed on the input signal, based on the result of the convolution operation, wherein the generating of the predetermined number of pseudo-random numbers having different phases is preformed by a plurality of generating paths, wherein one path of the plurality of generating paths generating pseudo-random numbers at a phase different from a phase of another path of the plurality of generating paths generating pseudo-random numbers.