| 摘要 |
PROBLEM TO BE SOLVED: To realize a highly reliable security function for preventing a portable communication terminal from being left behind, stolen or unauthorizedly used and protecting personal information. SOLUTION: A portable telephone terminal 6 is paired with a radio key 9 and portable telephone terminals 7 and 8 are paired with a radio key 10, respectively. The portable telephone terminal and the radio key forming a pair find absolute positions by a GPS, respectively and use the absolute positions to calculate a distance between the portable telephone terminal and the radio key. When an RSSI and a BER are good, the portable telephone terminal emits a warning to a user and starts a block function for limiting operation when the distance between the portable telephone terminal and the radio key is longer than a prescribed distance being a threshold. When the RSSI and the BER are good, the radio key emits a warning to the user when the distance between the portable telephone terminal and the key is longer than the prescribed distance being a threshold. COPYRIGHT: (C)2006,JPO&NCIPI
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