| 摘要 |
A polarity ring director for designating a specific party in a multi-party telephone system using polarity encoding to ring only a specific party's telephone includes a solid state bipolar switch connected in series with the subscriber telephone line. The bipolar switch is unipolar in one polarity to pass DC signals and is selectively unipolar in the opposite polarity to selectively pass AC signals in response to a pilot signal to ring the subscriber's telephone. A pilot switch is responsive to polarity encoded line conditions for generating the pilot signal. A polarity detection circuit responsive to a predetermined pattern of AC and DC voltages superimposed on three input channels selectively enables or disables the pilot switch. A telephone line addressing means couples the tip, ring and ground lines of a telphone system in a predetermined pattern to the three input channels.
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