To reduce periodic signals in pseudo-random noise.

This method includes a step for storing a set of digital values showing statistical characteristics selected by a memory (2) capable of designating an address with an n-bit address (a), a step for incrementing (10) an m-bit (m>n) address increment value (13) each with a regular interval (b), a step for changing (36 and 37) address increment values among selected limits (c), a step for designating an address in the memory with the most significant n-bit (11) of the number of m bits (d), a step for reading (5) a digital value from the memory with the address of the step (d) (e), a step for applying the digital value read in the step (e) to a DAC (6) to be able to obtain (7) an analog value (f), and a step for filtering (8) the analog value (g).