| 摘要 |
PURPOSE:To reduce remarkably the cost of equipment by using the echo cancel technology and eliminating the transmission signal component in a reception signal so as to eliminate the need for an expensive band separation filter. CONSTITUTION:An echo cancel signal is generated according to the characteristic of a transmission line from a transmission signal, the echo cancel signal is synthesized with a reception signal from the transmission line to eliminate the transmission signal component included in the reception signal thereby obtaining a signal in a reception band. The transmission signal component included in the reception signal is mixed directly by a hybrid circuit 5 and mixed from the opposite partly via the transmission line as the echo. A component e1 mixing directly an echo cancel signal to the transmission signal S and a component e2 obtained as an echo while delaying the component e1 via a transmission line are formed. Further, in order to make the elimination of the transmission signal component from the reception signal complete by the echo cancel signal, the transmission band component is extracted from the synthesis signal to correct the transmission line characteristic of an echo cancel section 6.
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