| 摘要 |
PURPOSE:To form a communication line between a central equipment and a terminal equipment with a 4-wire line by applying frequency multiplex to a voice signal and a control signal from the central equipment and a voice signal and a supervisory signal for air-monitor from the terminal equipment and sending the result to the central equipment through the communication line. CONSTITUTION:A voice signal outputted from a voice signal transmission section 12 of a central equipment transmission section 11 and a control signal for operation command or release command outputted from a control section 15 are sent to a transmission amplifier 14 and amplified and subject to frequency multiplex and sent to a communication line 39 as an outgoing signal. On the other hand, a voice signal outputted from a voice signal transmission section 31 for air-monitor of a terminal equipment transmission section 24 and a supervisory signal outputted from a supervisory section 34 are modulated by a modulator 35, amplified by a transmission amplifier 33, subject to frequency multiplex and sent to a communication line 42 as an incoming signal. Thus, the communication line between the central equipment and the terminal equipment is formed by a 4-wire line. |
