| 摘要 |
Access to a motor vehicle is controlled by periodically transmitting an interrogation signal from a control circuit on the vehicle. Upon receiving the interrogation signal, a hand-held remote control transmits a reply signal to the control circuit. The control circuit measures the strength of the reply signal and the activates a first function, such as unlocking a door of the vehicle, when the strength exceeds a first threshold level. Thereafter, when the signal strength exceeds a second threshold level, the control circuit activates a second function, for example enabling the engine to be started. When the signal strength drops below a third threshold activates a third function, such as locking the door. |
