ADDITIVE PCM SPEAKER CIRCUIT FOR A TIME SHARED ISDN CONFERENCE ARRANGEMENT

摘要

ADDITIVE PCM SPEAKER CIRCUIT FOR ATIME SHARED ISDN CONFERENCE ARRANGEMENTABSTRACT OF THE DISCLOSUREA time shared multiport conference arrangementincludes an additive PCM speaker circuit. The additivePCM speaker circuit eliminates the need for loudestspeaker detection and the last speaker memory ofconventional conferencing arrangements. The additivePCM speaker circuitry operates in an on-line, real timeenvironment to allow rapid conversion and summing ofspeakers' PCM voice samples. Since the PCM voicesamples are logarithmic in nature, they are notdirectly combinable. The additive PCM speakercircuitry provides for converting the logarithmic PCMsignals to linear form. Next, the linear signals of upto three conferees are buffered. Then the speakers'linear form samples are added and each combinationreconverted from linear to logarithmic form. Theadditive PCM spearer circuit simplifies the complexprocessing logic usually associated with loudestspeaker detection systems and thereby improves the realtime operation of the conferencing arrangement.