| 摘要 |
<p>51 A method of reducing the convergence time of an echo canceller including a transversal filter having N coefficients comprises at least the following steps: - transmission of a training data signal D(n) constituted by data transmitted at instants nT, T being the data interval, and being periodically reproduced after a duration LT at least equal to NT and having the property: where d and d* are the value of the data signal D(n) and its complex conjugate value, respectively; - calculation of the coefficients of the transversal filter carried out after the instant of appearance of the echo signal produced in response to the training signal in accordance with the expression: where CO and C are the vectors of the N coefficients of the transversal filter at the beginning and at the end of the period of calculating the coefficients, respectively, e(n) is the difference signal, ?*(n) is the vector of the complex conjugate values of the N data stored in the transversal filter, and .sigma.2 is a constant term representative of the power of each of the transmitted data. This method applied to a linear echo canceller permits initializing of the coefficients of the transversal filter of the echo canceller within a time 2NT, where NT is the duration of the echo.</p> |
