| 摘要 |
In a passive entry comprising a car-mounted transmitter-receiver and one or more portable transmitter-receivers, the car-mounted transmitter-receiver generates a request signal, when any of the portable transmitter-receivers receives the request signal, an answer signal is transmitted in response to the request signal, and when the car-mounted transmitter-receiver receives the answer signal, the car door is locked or unlocked. The car-mounted transmitter-receiver has a timer for counting time from transmission of the request signal to reception of the answer signal, and when the answer signal is received, recognizes the answer signal as legal only when an elapsed-time value counted by the timer is within a valid elapsed-time value set in advance, and exercises control of a controlled apparatus, such as, e.g., locking and unlocking of the car door.
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