| 摘要 |
Echo canceler associated with a modem utilizing amplitude and phase modulation of a carrier, the echo canceler comprising adaptive filters (16-1) to (16-p) producing signals which are combined in an adder (15) for forming a synthetic echo signal epsilon (n). The coefficients of these filters are adjusted to minimize the mean square value of the residual echo signal e(n)= epsilon (n)- epsilon (n), where epsilon (n) is the echo received. The echo canceler comprises a code conversion circuit (17) which receives a signal D(n) characterizing in each modulation interval the amplitude and phase state of the carrier to be transmitted and which produces distinct configurations of several numbers of values +1, -1 or 0, said distinct configurations corresponding to the distinct possible states of the carrier to be transmitted such that elementary signals D1(n) to Dp(n) are formed which are mutually independent in the mean and which are applied to the filters (16-1) to (16-p). These filters can then be realized in a simple way.
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