| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a smart key system capable of increasing probability of success of bidirectional communication between a portable unit and a controller even when level of noise around a vehicle is high. <P>SOLUTION: In this smart key system, a period of transmission continuation of a synchronous signal by a vehicle controller 2 is prolonged if communication environment around the vehicle is bad to such extent that obstructs the communication between the portable unit 1 and the vehicle controller 2. Consequently, since termination of the period of transmission continuation of the synchronous signal in a predetermined period cannot be recognized through a valid antenna in the situation where the communication environment around the vehicle is bad, the valid antenna is predetermined again. A receiving antenna being different from the preceding valid antenna can be predetermined as the valid antenna. <P>COPYRIGHT: (C)2010,JPO&INPIT |
