| 摘要 |
A remote-control vehicle lock-and-alarm system provides improved security against "code-grabber" devices used to detect and counterfeit the codes used by a vehicle lock-and-alarm system. Two sets of control codes are provided. One set of control codes that does not affect the security status of the lock-and-alarm system is transmitted over a maximum range, for the sake of convenience. The other set of control codes is used for critical security features which change the security status of the lock-and-alarm system and is transmitted over a much shorter range to prevent detection and counterfeiting of the control codes.
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