| 摘要 |
PROBLEM TO BE SOLVED: To provide an automatic meter-reading system for simplifying a communication procedure between a portable terminal and a radio terminal.SOLUTION: The automatic meter-reading system includes: a plurality of radio terminals; an automatic meter-reading server for transmitting a radio signal to the plurality of radio terminals, and for receiving and collecting the measurement data of a plurality of measurement units from the plurality of radio terminals; and a portable terminal capable of performing radio communication with the radio terminal. Between the automatic meter-reading server and the plurality of radio terminals and between the plurality of radio terminals and the portable terminal, radio communication is performed by applying time-division multiplex to downlink and uplink in a modulation system of performing spectral diffusion by diffusion code system. The radio terminal determines a radio power to be transmitted in the uplink on the basis of the radio power of the radio signal received in the downlink. The portable terminal detects the period of the downlink, and transmits the radio signal which has been subjected to the spectral diffusion by the same diffusion code system as that of the automatic meter-reading server to the radio terminal in the period of the downlink, and receives the radio signal from the radio terminal in the uplink. |
