| 摘要 |
PURPOSE:To obtain an echo canceler with the large amount of echo cancellation, by providing an echo canceler, inserted into a digital four-wire circuit differing in synchronism between transmission and reception, with an interpolating filter, echo path model, echo cancellation part, and subtracter. CONSTITUTION:An interpolating filter 200 receives and stores a reception-side digital signal, has filter coefficients, and filters the stored reception-side digital signal by making the filter coefficients operate upon it successively to output results of filtering successively in one sampling period. An echo path model 110 which outputs the signal of the filter 200 and simulates an echo path, and a subtracter 120 which finds a difference between the output signal of the model 110 and a transmission- side input digital signal are provided. Then, the output of the substractor 120 is made by an echo cancellation part 100 into a transmission-side output digital signal, which is outputted to a transmission-side output terminal 3. Thus, an echo canceler of simple constitution for a digital interface with the large amount of echo cancellation is realized. |
