| 摘要 |
<P>PROBLEM TO BE SOLVED: To stably identify a silent-mode area while suppressing power consumption increase a little by using existent C/A codes. <P>SOLUTION: A use restriction system 1 includes an identification signal generating device 2 for generating a silent-mode area signal and a transmission antenna 3 installed in a silent-mode area for transmitting the silent-mode area signal generated by the identification signal generating device 2. The identification signal generating device 2 includes a diffusion section 25c for performing diffusion processing using a C/A code of a GPS satellite with which a transmission radio wave does not reach the silent-mode area; and a modulation section 25d for modulating a signal after diffusion processing into a GPS form and outputting the signal. Furthermore, a cellular phone 4 includes: a receiving antenna 41 for receiving the signal of the GPS form; an inverse diffusion section 43 for applying inverse diffusion processing to the signal received by the receiving antenna 41 using a C/A code of the GPS satellite with which a transmission radio wave does not reach the silent-mode area; and a use restriction control section 47 for implementing use restriction of the cellular phone 4 in accordance with whether or not inverse diffusion processing is enabled. <P>COPYRIGHT: (C)2011,JPO&INPIT |
