| 摘要 |
An analog echo suppression circuit is used with a telephony 2-wire circuit to 4-wire circuit interface. The 2-wire circuit carries a first signal and the 4-wire circuit carries a second signal. Each circuit has an input port and an output port. The interface produces an echo signal on the output of the 2-wire circuit when the second signal is received at the input port of the 2-wire circuit. A first communication channel connects the output of the 4-wire circuit to the input of the 2-wire circuit. A second communication channel connects the output of the 2-wire circuit to the input of the 4-wire circuit and series analog switches or transmission gates can interrupt the second channel. A comparator circuit receives the first and second signals from the first and second channels and has first and second outputs. First and second controller devices are operatively connected to the comparator circuit and provide signals such that, if an echo signal is present, the one analog switch interrupts the second channel and another analog switch grounds the input to the 4-wire circuit.
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