| 摘要 |
Digital filters are used to simulate the transmission function of a real system by means of echo cancellers, where a high-speed digital signal processor with a large memory is needed to compute and update the filter coefficients. To reduce the cost of the echo canceller, an autocorrelation, i.e. the correlation of a block of a defined number of sampling values of the transmitted signal with received echoes derived from this transmitted signal, is used by the invention to determine the time periods at which an echo arrives, and at which an update of the filter coefficients then takes place. In this way the number of filter coefficients to be computed and the cost of their computation are significantly reduced, so that echo cancellers for telephone terminals can be produced in a cost-effective manner.
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