| 摘要 |
PURPOSE:To improve circuit efficiency by transmitting a synchronizing signal and sensing signal through different circuits by making use of an earth circuit and also by multiplexing the sensing signals in time-division mode synchronizing with synchronizing signal. CONSTITUTION:To transmission circuits L1 and L2 between central unit 1 and terminal equipment 2, currents are flowed by using circuit L1 and the earth, and circuit L2 and the earth respectively, and consequently one circuit can separately be used. Therefore, circuit L1 is used as line for sending signal (b) including sensing signals D1-D4 from terminal equipment 2 to central unit 1, and circuit L2 as a line for transmitting signal (a) such as a synchronizing signal from central unit 1 to terminal equipment 2. Through control circuit 1-5, MODEM circuit 1-6 generates at its output side initial synchronizing pulse (x) between circuit L2 and the earth with pulses generated by initial synchronizing signal generating circuit 1-1 and when the synchronizing signal from synchronizing signal generating circuit 1-3 is received, pulse signals (y) and (z) are similarly generated. |
