TRANSMISSION SWITCHING CONTROL SYSTEM FOR PLURAL TRANSMISSION STATIONS

PURPOSE:To attain transmission switching between plural transmission stations without intermission continuously by sending a timing signal before the prescribed time of the end of transmission and allowing the transmission station scheduled for succeeding transmission to start transmission based on the timing signal. CONSTITUTION:When an external transmission control trigger is received before a prescribed time of the end of transmission while a transmission station A is in transmission, a residual time generating circuit 1 generates a count-down timing signal to make a transmission end time zero and outputs a transmission stop signal at the time of the end of transmission. An information signal coding circuit 2 encodes the timing signal and sends it to a transmission line via a multiplexer circuit 3 and a transmission reception circuit 4. On the other hand, the transmission station B of succeeding transmission receives a multiplex signal from the transmission station A, a demodulation circuit 5 separates a main signal and a coding signal, an information signal decoding circuit 6 extracts the timing signal and a switching signal. Then a residual time counter circuit 7 outputs a transmission starting signal to the circuit 4 at the arrival of the transmission end time. Thus, the transmission line is effectively used.