| 摘要 |
PURPOSE:To attain economy and to suppress generation of a code error by applying phase modulation or frequency modulation to a control instruction controlling the operating state of a repeater, sending the result and returning an acknowledge signal in a frequency different from the carrier frequency of the sender side. CONSTITUTION:A control instruction signal W outputted from a control instruction generator 12 is formed into a keying signal E by applying keying (modulation) to a carrier C from a carrier generating circuit 111 at a preliminary modulation circuit 112. The signal E is inputted to a phase modulation circuit 110 to modulate a pulse phase of a communication signal S thereby obtaining a transmission signal D being the superimposition of the signals S, W. As the carrier frequency of the acknowledge signal from the repeater, the frequency dividing or multiplying the carrier frequency for transmission is used. Thus, the signal is sent to an optical fiber 2s in in-service, the production of S/N code error is suppressed, and a standby system or the like is not required and economy is attained. |
