| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a system capable of reliably selecting in advance a frequency at which interference of the transmission signal of a portable communication device and noise is not caused. <P>SOLUTION: Between a vehicle-side communication device and a portable communication device, prior to LF-RF communication, RF-RF communication of a wide communication range is performed beforehand while changing a frequency, and the frequency of an RF signal not to be interfered by noise is selected. Then, when the vehicle-side communication device and the portable communication device are within a distance where the LF-RF communication can be performed, the portable communication device transmits by radio a transmission signal at the previously selected frequency. <P>COPYRIGHT: (C)2009,JPO&INPIT |
