| 摘要 |
Subscriber's circuit for connecting a subscriber's line to a telephone exchange, comprising a symmetrical amplifier which is arranged between two feed points having different potentials, the amplifier circuit having two input terminals and two output terminals, each one of the output terminals being connected to a wire of the subscriber's line and each input terminal of the symmetrical amplifier circuit being connected to an output of an associated digital-to-analog converter an input of which is connected to the one or to the other feed point by means of a change-over switch, the change-over switches being controlled in phase opposition by a binary digital signal which characterizes a voltage desired for the subscriber's line and which is derived from a digital signal generator under the control of the telephone exchange.
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