| 摘要 |
PROBLEM TO BE SOLVED: To secure both convenience in a quick walking pace and crime- prevention in a slow walking pace, by locking or unlocking vehicle doors through an on-board instrument by a receiving electric field strength of a transmission signal from a portable instrument provided with a variable switch for the frequency of the transmission signal. SOLUTION: This system is provided with a portable instrument 1 outputting a transmission signalαand an on-board instrument 3 locking or unlocking vehicle doors through a door lock actuator 2 on the basis of the receiving electric field strength. The on-board instrument 3 executes locking or unlocking of the vehicle doors on the basis of the receiving electric field strength of the transmission signalα: from the portable instrument 1. When manipulating a switch in the portable instrument 1, the frequency of the transmission signalαis changed. Hence, when the transmission frequency is shortened by the switching control, convenience in a quick pace can be secured and when the frequency is prolonged, crime-prevention in a slow pace can be secured. In this way, both convenience and crime-prevention can be compatibly secured.
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