PCM MODEM ADAPTATION SYSTEM UTILIZING A SILENCE PERIOD

摘要

In a full duplex PCM modem system (figure 2), a method and apparatus is provided for robust measuring of the communications channel (67) in which th e digital modem (26) transmitter is silenced (54) during generation of trainin g signal by analog modem (12), with silencing of the digital modem's transmitt er eliminating problems associated with echo during channel measurement at the digital modem. The above method thus eliminates echo during channel estimati on and removes any dependencies on the performance of the echo canceller normal ly used.