Adaptive decision feedback equalisation of line signals in electrical communications

摘要

Method and circuit arrangements for adaptive decision feedback equalisation of line signals in electrical communications In high-speed digital signal transmission, the incoming line signal presents post-oscillations due to shortcomings in the transmission path. These post-oscillations can be cancelled with an adaptive decision feedback equaliser. In order to achieve a high convergence speed, it is known for the adjustment step factor which is required for coefficient calculation to be designed as variable. If relatively long post-oscillations are intended to be completely cancelled with an echo canceller of this type comprising a single adaptive transverse filter, this filter must have an economically unviable number of elements. Furthermore, a large number of elements allows only a small adjustment step factor, which restricts the ability to achieve a high convergence speed. The object is to achieve a high convergence speed at low cost, even in the case of long post-oscillations. A second non-adaptive filter (RF) is connected downstream of the adaptive transverse filter (AF). Further features indicate, inter alia, how the variable adjustment step factor (v) can be obtained (Fig. 1). The invention is suitable for use in the transmission modules of the integrated services digital telecommunications network (ISDN).