| 摘要 |
In the PBX, the circuit improves characteristics of ring detection and line state inspection by simplifying complexity of structure and improving the characteristics of voice. The circuit consists of a relay block (301) connected to tip and ring endpoint and connecting voice path, a line state inspector (302) monitoring the state of line, a transformer (303) used to DC separating and an impedance matching and balancing network block (304) balancing Tx, Rx and impedance.
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