| 摘要 |
PURPOSE:To decrease the time required for communication procedures and to reduce the communication cost with a picture communication device, by switching the 1st MODEM means to the 2nd MODEM means by a control means in case the control signal to be demodulated by the 2nd MODEM means is supplied to the 1st MODEM means. CONSTITUTION:A switch circuit 5 performs switching between a control signal MODEM6 and a picture signal MODEM7 by an MODEM switch instruction signal delivered from a central controller 1 via a signal line (f). The MODEM6 modulates and demodulates the binary signal having 300bps transmission speed; while the MODEM7 modulates and demodulates the picture signal and the EOP signal, etc. which is transmitted at the same speed as the picture signal. The MODEM7 receives the picture signals and sets a signal line CD at an H level and then at an L level when no picture signal is received. Furthermore the MODEM7 sets a signal line FAIL at an H level with reception of the binary signal of 300bps and then at an L level when no said binary signal is received respectively.
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