An all-digital audioconference bridge based on a four-wire networkconnection has been implemented. The audioconference bridge isimplemented as a wire-wrap plug-in board to a digital exchange on a2.048 Mb/s 32-channel PCM (pulse code modulation) link. The digitalsystem is superior to the existing analog audioconference systems bothin terms of setup time and quality of transmission. A general bridge hasbeen designed which can alternate between different meeting strategiesin order to compare the performances of the strategies under the sameconditions of transmission. New meeting strategies can easily beimplemented because of program controlled switching. Subjective testshave established that the quality of transmission can be improvednoticeably by using the two instant speakers algorithm instead of theclassical addition or instant speaker algorithms. By using a `meet-me'setup system a subscriber can call the bridge with an ordinarytelephone, thus speeding up the startup procedure and distributingefforts and costs among the participants. This procedure is much easierthan the operator handled startup as found in previous systems
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