Noise generator

Abstract

A noise generator in which a random pulse output is produced by a random pulse generator in synchronism with a predetermined clock and is stored in a latch circuit by a clock obtained by frequency dividing the predetermined clock to produce random pulses of a harmonic composition different from the abovesaid random pulse output, thus providing noises of two or more desired harmonic compositions from the random pulse generator. A band noise generator in which parallel outputs from respective stages of a random pulse generator are divided into two, that is, inter and decimal bits; a noise band width is designated by a band width designating circuit; a frequency coefficient represented by an integer corresponding to the band width is read out by the integer bits; the frequency coefficient thus read out is added to a fundamental frequency coefficient represented by an integer, stored in a memory, to produce predetermined output bits; the output bits are added with the decimal bits from the random pulse generator and accumulated by an accumulator in synchronism with a clock to output predetermined high-order bits; and in accordance with the output content, a sine wave is read from a sine-wave table. Thus, a desired noise band width can be set by the band width designating circuit, and by accumulating the decimal bits using the accumulator, setting including the decimal bits is made possible, thereby obtaining band noises whose frequencies are set with high accuracy.