| 摘要 |
In a portable radio information terminal 7, if both the present level of the battery capacity and the level of received signal strength are above respective thresholds at which data communication is possible, the portable terminal 7 sends a data transmission/reception possible or enabling signal via a base station 6 to a supervising servers in an information network centre 1. If the battery level is below the data communication threshold, the terminal 7 sends a data transmission/reception impossible or disabling signal to the server 5. The terminal 7 also sends the impossible/disabling signal if the received signal strength is below the data communication threshold. A display (19. Fig.2) on the terminal may indicate whether data communication is possible or impossible. Data is not sent from the centre 1 to the portable terminal 7 unless the server 5 has received the data transmission/ reception possible signal from terminal 7. This avoids having to re-transmit data from the centre 1 in circumstances where the terminal 7 would initially not be able to receive it. The terminal 7 may send a specified time signal when data communication is to be made within a specified time, checking of battery level and received signal strength, and the resultant sending of the data transmission/reception possible signal or impossible signal, then being done when a specified time acceptance signal is received by terminal 7 from the centre 1 or when the specified time signal has been sent from the terminal 7 for a certain number of times without a specified time acceptance signal being received from the centre 1 (Figs.8-10). |
