Image Number 6 for United States Patent #5029162.
An automatic gain control for an inputted multiplex PCM data stream in a conferencing bridge in a telephone system. The inputted multiplexed data stream has a predetermined number of time slots wherein each time slot carries PCM speech data corresponding to an individual party in the conference call. The control of the present invention is capable of operating in .mu.-Law or A-Law companded format at a frequency of 192-256 kilobytes per second. The automatic gain control incorporates a digital root-mean-square meter, a COUNT sequence to change GAIN at predetermined intervals, and a set of GAIN rules to selectively increase or decrease GAIN based upon the output of the digital root-mean-square meter.