| 摘要 |
PURPOSE:To synchronize the phase of transmission signal of each transmission station economically by providing a phase difference detection control section to a central station, returning data sent from the central station via a wired line by a returning circuit provided to each transmission station, detecting the phase difference and controlling the phase of transmission of the data. CONSTITUTION:The returned data 30 from a transmission station is demodulated by a demodulator 17 and fed to a phase shifter 14. A bit timing signal recovered by a bit timing recovery circuit 18 is subjected to phase comparison with a clock signal 23 by a phase comparator 15 and a phase difference signal 28 is fed as a control signal of phase shifters 13, 14. The phase difference between sent data 29 and the returned data 30 is detected by the phase comparator 15 to control the phase of the sent data 29 by the phase shifter 13 corresponding to a phase difference signal 28 thereby compensating the change in the transmission delay quantity of a wired line, then the synchronizing state of the phase of the transmission signal of a transmission station with the phase of the transmission signal of other transmission station is kept. |
