Semi-recursive adaptive equalizer

Abstract

An adaptive equalizer includes a digital linear filter having adjustable weighting factors and which is connected to a summator and a control unit so as to form two filter loops, one direct and the other recursive, the filter being shared in both loops. The control unit provides a weighting factor which establishes a selected relative proportioning of the data signals which traverse each loop, so that the equalizer is proportioned as to the degree to which it provides direct filtering and the degree to which it provides recursive filtering. Recursive filtering is employed to the maximum extent consistent with operating stability, the relative proportion of direct filtering being increased as necessary in order to maintain stability during equalization of any particular received data signal.