IDLE CHANNEL NOISE REDUCTION IN A LINE CARD HAVING A DSP EQUALIZER

摘要

IDLE CHANNEL NOISE REDUCTION IN A LINE CARD HAVING A DSP EQUALIZER Idle channel noise reduction is achieved in a line card having an analog gain/attenuator, a codec, and a digital signal processor including an equalizer and a digital gain/attenuator. A peak detector samples output from the codec each 8 kHz cycle. A level decision compares the sample to a stored peak value, and replaces the stored peak value with the sample if it is greater. A controller, at a second predetermined interval, increases analog gain in steps and increases digital attenuation in similar steps if the stored peak value is greater than the predetermined threshold. Otherwise, the controller increases analog attenuation in steps and increases digital gain in similar steps.