| 摘要 |
PURPOSE:To decrease the number of wirings greatly and to improve construction workability, by transmitting a sound signal, video signal, control signal, electric power, etc., through two transmission lines by a frequency-division system. CONSTITUTION:When the button 8 of a subordinate station is pressed, a television camera 7 is put in operation and a transmission code is sent by a transmitter 17 and a transmission code generating circuit 18 to a master station. The subordinate station receives a sent-back code from the master station and when a received code deciding circuit 12 decides that the sent-back code is adequate, an aural signal device and video device start operation to permit a talk. An end signal is transmitted only from the master station and turns off said device. At the master station, a received code deciding circuit 23 decides on the transmitted code of the subordinate station to return it by a transmitted code generating circuit 30 and a transmitter 29. When the code is adequate and the transmitted code from the subordinate station does not arraives any more after the code is returned to the subordinate station, a chime 6, monitor television 4, monitor television driving circuit 25, video demodulating circuit, and transmitter 29 start operating to allow a mutual talk. |
