PATH CHANGE DETECTOR FOR ECHO CANCELLATION

摘要

A path change is detected by multiplying (83) the energy of a signal on the output of a summation circuit (72) in one channel of a telephone by a constant to produce a product. The product is compared (84) with the energy of a signal on the input of the summation circuit. A path change is indicated when the energy of the product exceeds the energy of a signal on the input of the summation circuit. The comparison is made in successive frames (87) of an audio signal and a path change is indicated when the energy of a signal on the input of the summation circuit is exceeded in two or more successive frames.