Patent ID: 6735303
Filing Date: 2004-05-11
Classification: H04B

Abstract:
A periodic signal detector for an echo canceller apparatus including an echo canceller and a controller for controlling said echo canceller in accordance with an output signal from the periodic signal detector, the periodic signal detector comprising:sample counting means for counting the number of samples between adjacent zero cross points in an input signal, the sample counting means outputting the number of samples each time the number of samples between the adjacent zero cross points is obtained, and continuing outputting the number of samples until a next zero cross point is detected; and detecting means for detecting a section, as a periodic signal section, in which the output from the sample counting means has a constant result, said detecting means including a zero counting means for counting the number of successively sampled zeros included in the output from a high-pass filter, and a judgment circuit for determining a section, as the periodic signal section, in which an output from the zero counting means is not less than a predetermined threshold value and providing a signal representative thereof as the output signal.