| 摘要 |
A control unit of a key device in an access control system interrogates a transponder associated with the key device in order to determine whether it has been removed or replaced. An embodiment of the invention relates to a remote vehicle access systems in which an access code is transmitted from a key fob 70 to a vehicle access system 72 and in which the key fob has an associated backup key 60 for use in case of failure on the part of transmitter system 74,76. A control unit of the key can determine whether or not the transponder 62 of the backup key has been removed or replaced by way of the use of micro-switches or by communicating with the transponder so as to read it is stored code. The results of this interrogation can be used to inform a user if the transponder has been removed and replaced. The results can also be transmitted to the access control system of the vehicle which may then use the results to affect control of the vehicle; for example limiting the speed of the vehicle if the transponder has been tampered with or replaced. In an alternative embodiment the code of the transponder 62 is assessed by the access control system 72.
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