METHOD AND APPARATUS FOR REDUCTION OF UNWANTED FEEDBACK

摘要

The feedback caused between the output (39) and the input (30) of an amplification path (54, 42, 56, 60, 62, 64) is reduced by providing a delay (60) in the amplification path, passing through the amplification path a signal having an auto-correlation function which is substantially a delta function, correlating (72) the said signal before being delayed in the delay with the signal after being delayed in the delay to produce a plurality of correlation coefficients, modifying the signal in the amplification path to provide a modified signal, the modification being provided by a transversal filter (76) controlled by the said plurality of correlation coefficients, and combining (42) the modified signal with the signal in the amplification path so as to reduce the effect of the feedback. The signal having an auto-correlation function which is substantially a delta function may be an added noise signal (70) or may be constituted by the signal being processed itself. The system can be used to reduce "howl-around" in audio situations or feedback in simultaneous coherent re-broadcast transceivers.