| 摘要 |
PURPOSE:To contrive to reduce the output of a transmitter and to omit the antenna or the like to not only simplify the equipment but reduce the cost by providing a repeater which radiates the modulated wave signal from a transmitter as a radio wave and using a commercial power line, an indoor wiring, or the like for connection between the transmitter and the repeater. CONSTITUTION:The modulated wave signal where an individual password number, a message, a repeater selecting signal, etc., are converted to a digital code is transmitted from a transmitter 1 to a commercial power line 4, and this signal is received by repeaters 2a, 2b and 2c and is converted to a radio wave and is radiated to the space, and this radio wave is received by a mobile machine 3, and the message is transmitted to its owner if respective individual password numbers coincide with each other. An overall service area 7 is divided into zones A, B and C, and the first-third repeaters 2a, 2b and 2c are installed in zones A-C respectively, and the repeater from which the radio wave should be transmitted out of the first-third repeaters is determined by the repeater selecting signal included in the output of a transmitter 1, and the same individual password number and message are transmitted to zones A-C in time division by repeaters 2a, 2b and 2c. |
