| 摘要 |
PURPOSE:To reduce the deterioration in talking quality by connecting a high impedance means in series with a feeding loopback circuit of a feeding loopback station so as to reduce the effect of electromagnetic induction when a communication cable energized by one-way feeding system is subjected to electromagnetic induction from a high voltage power cable installed in parallel. CONSTITUTION:If a fault takes place in a 2nd feeding circuit 5 and one-way feeding is applied from a 1st feeding circuit 4, the 2nd feeding circuit having a function suppressing 50/60Hz components is disconnected and instead a current return is formed by a feeding loopback circuit 6 having no suppressing function. Since the 50/60Hz components are suppressed by the 1st feeding circuit 4 only, the suppressing effect is reduced and the talking quality is deteriorated. Then a high impedance means 7 giving a high impedance at 50/60Hz is connected in series with the feeding loopback circuit 6 to suppress the 50/60Hz components at the feeding loopback point in case of one-way feeding. Thus, the deterioration in the talking quality is improved.
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