Patent ID: 7747027

Claim:
A test-tone-signal generating circuit, comprising: a fundamental tone generator configured to generate a fundamental tone signal, which is a sinusoidal signal having a predetermined frequency; a harmonic tone generator configured to generate a plurality of harmonic tone signals having different frequencies that are integral multiples of the predetermined frequency; an adder configured to add the fundamental tone signal to the harmonic tone signals to generate a test tone signal; and a controller configured to control the harmonic tone generator so as to generate a first group of the harmonic tone signals and a second group of the harmonic tone signals, at least part of the second group of the harmonic tone amplifying frequencies different from frequencies of the first group of the harmonic tone signals, wherein the controller outputs the test tone signal including the first group of the harmonic tone signals and the test tone signal including the second group of the harmonic tone signals at predetermined intervals.