| 摘要 |
PURPOSE:To apply a signal to a distribution line on the way by applying a carrier signal obtained through the modulation of a carrier of other frequency again between the distribution line and ground and leading and demodulating the carrier converted and induced between the distribution line and ground in a receiver. CONSTITUTION:The output of a carrier oscillator 15 is modulated by the output of a supervisory controlling equipment 16. Moreover, in a repeater 10, a zero- phase current transformer 17 and an injection transformer 18 are coupled to an earth line 5 provided to a transformer 1, a signal induced in the zero-phase current transformer 17 is amplified up to a prescribed level by an amplifier 19 and led to a frequency converter circuit 20 to extract a carrier signal component fed from a supervisory equipment 11 to the distribution line. Moreover, the signal is converted into a signal having other frequency than the said frequency and fed to the injection transformer 18 via an amplifier 21. In a receiver 12, a receiver 24 is connected between the earth distribution line 3 and a connecting point 22 of ground, the receiver 24 is connected via a DC blocking capacitor 23 to receive and demodulate a carrier signal.
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