DC RESTORATION CIRCUIT FOR A RADIO RECEIVER

摘要

This invention relates to communications (radio) receiver circuitry and , in particular, to circuitry for eliminating a varying DC distortion componen t of a demodulated received information signal such as comprising data packets. This invention uses an adaptive filter, and a corresponding adaptive (equalization) feedback signal, to remove a slow varying (exponential) DC component of the signal. In the decoding circuitry of a receiver the adaptiv e filter (e.g. an LMS filter) compares the outputs of an integrate and dump component to adapted outputs of a decision component in order to produce an error signal which inherently corresponds to the varying DC component of the symbol stream. This equalizing adaptive error signal is fed back and subtracted from the symbol integral stream to remove the varying DC component therefrom and thereby restore the information packet to a level DC bias condition.