Noise reduction method, e.g. for car radio receiver, involves varying audio signal passband with adaptive low-pass filter controlled according to received signal strength

摘要

A method for noise suppression in a digital signal path, where received signal strength is measured (P) and from this a control signal is derived and used to vary the cut-off frequency of an adaptive low pass filter (TP). When applied to a radio receiver, input audio signals (A) are digitized (AD), fed via a DSP stage (DP) and then filtered according to signal strength before being converted (DA) back into analog form (C). An Independent claim is included for a noise reduction circuit.