| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a passive keyless entry system that adjusts the transmission and reception signal levels of transmitter/receiver carried by cars, in response to changes in the arrangement state, between the transmitter/receivers 1 carried by vehicles and a corresponding portable one. <P>SOLUTION: In this passive keyless entry system, a portable transmitter/receiver 1 is provided with a receiving antenna 7 for receiving wake-up signals, a signal receiving part 3 including a wave detection part 3D for signal processings, a signal level decision part for determining whether the received signal level is higher than the allowable input level of the wave detection part 3D and outputting the determination results, a controller 5 and a signal transmitter 6 for transmitting signals to a transmitter/receiver carried by cars. If the signal level determining part 4 outputs a determination result that the allowable input value of the wave detection part 3D has been exceeded, the controller 5 transmits a request signal to the transmitter/receiver 1 of cars via the signal transmitting part 6; and upon receiving this signal, the transmitter/receiver of the car drops the signal level to the portable transmitter/receiver by a fixed level, and retransmits a wake-up signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI</p> |
