DIGITAL AUTOMATIC GAIN CONTROL WITH FEEDBACK INDUCED NOISE SUPPRESSION

摘要

Method processor and processor-readable medium for reducing the level of feedback-induced noise in the output signal from an audio automatic gain control circuit are provided. The method allows for receiving a stream of pulses comprising an input signal to the automatic gain control circuit. The method further allows for receiving estimates of respective high and low frequency energy components of the input signal. The respective high and low frequency components are averaged, e.g., over a respective sliding window. An energy scalar is calculated based on the ratio of a predefined target energy level over a combined value of the high and low frequency components. A relating action allows to compare the target energy level to the combined value of the high and low frequency components. Based on the comparison results, the calculated energy scalar is limited to within the two limit values. A subsequent relating action allows to compare the values of the averages of the high and low frequency components to one another. If the value of the high frequency average exceeds the value of the low frequency average, the energy scalar is reduced to a value sufficiently low to suppress the presence of feedback-induced noise in the input signal of the circuit, and generate an output signal with a corresponding low level of feedback-induced noise. If the value of the low frequency average exceeds the value of the high frequency average, the energy scalar is applied to the input signal to generate an output signal scaled within the two limit values.