| 摘要 |
PROBLEM TO BE SOLVED: To prevent a door from being unlocked by an illegal act.SOLUTION: Each time a code for identifying a portable communication terminal is received, power P(t) of a digital signal in receiving the code is compared with power P(t-1) of a digital signal in receiving another code before receiving the code (step S108). In the case where a difference between the power P(t) and the power P(t-1) is equal to or more than a threshold Th, a determination signal is brought into a low level (step S109) and a demodulation signal which should be outputted to a digital receiver is cut off. Thus, a door of a vehicle is prevented from being unlocked. |
