| 摘要 |
PURPOSE:To eliminate completely crosstalk practically by controlling turn-on/off timings of the first and the second analog switches exclusively at such switching period that an audio analog signal can be reproduced. CONSTITUTION:The transmission audio signal from a telephone set is supplied from an analog switch 6 to a converting circuit 3 through an amplifier 2 at the timing indicated by hatching in a figure 11. The reception signal from a line is supplied to the telephone side from an analog switch 7 at the timing indicated by hatching in a figure 12. Switches 6 and 7 are turned on/off exclusively by a control signal 10 of a square wave having, for example, 8kHz frequency. Thus, the switch 6 is turned off at the timing, when the reception audio signal passes the switch 7, and the switch 7 is turned off at the timing, when the transmission audio signal passes the switch 6, as shown in figures 11 and 12.
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