| 摘要 |
PURPOSE:To save electric power and to reduce a transmitting device in size by synchronizing the transmitting device with plural receiving devices on the basis of the time data of a reference timer circuit provided to the transmitting device and powering off the receiving device except at the communication allotted time of selective call data. CONSTITUTION:A BCH encoding circuit 2D performs the abbreviated flange encoding of input data and supplies the result to an FSK encoder 2E and actual transmit data represented by signals of 1,200 and 2,400Hz is generated for transmitting data at 600Hz and supplied to a transmitter 2. Consequently, the transmit data is transmitted from all antennas 2H1-2Hk through a distributor 2G and received by antennas 41-4m of wrist watches of respective employees. When the call code of each employee is detected in this receive signal, the transistor of a power-source cutting off circuit is on without fail and receiving operation is performed. |
