| 摘要 |
A drive-away prevention security system used in connection with an RF remote keyless entry system. A microprocessor and associated circuitry are configured within the head of an ignition key for a vehicle such that when a function switch on the key head is activated, a coded signal is transmitted to be received by a receiver within the vehicle. The receiver deciphers the received coded transmission to determine if a valid signal has been transmitted, and performs a vehicle function, such as locking or unlocking the vehicle doors, if the coded signal is valid. When the ignition key is inserted in the ignition switch of the vehicle, an ignition signal is sent to a microprocessor associated with the receiver. The microprocessor causes an on/off signal to be applied to an oscillator at the ignition switch in accordance with a data scheme. The oscillator energizes a coil at the ignition switch that generates a time-varying magnetic field inductively coupling the magnetic field lines to the coil within the ignition key. The microprocessor in the key analyzes the data sequence transmitted by the time-varying magnetic field, and emits the coded signal if the time-varying magnetic field is valid. The receiver receives the coded beacon signal and causes a start/enable signal to be sent to an engine module if the signal is valid. |
