Passive remote access control system
AssigneeDelphi Automotive Systems
InventorsMarc R. Simon, Francois Lhomme, Christophe Leligne
Life of this patent
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Abstract
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.
Claims16
A method for controlling access to a vehicle which has a door and an engine, that method comprising the steps of:
- (a) periodically transmitting a first interrogation signal at a first rate from a control circuit on the vehicle;
- (b) receiving the first interrogation signal at a remote control that is separate from the vehicle;
- (c) upon receiving the first interrogation signal, transmitting a first reply signal from the remote control;
- (d) receiving the first reply signal at the control circuit;
- (e) after receiving the first reply signal, periodically transmitting a second interrogation signal at a second rate from the control circuit;
- (f) receiving the second interrogation signal at the remote control;
- (g) upon receiving each second interrogation signal, transmitting a second reply signal from the remote control;
- (h) receiving each second reply signal at the control circuit;
- (i) measuring strength of each second reply signal at the control circuit;
- (j) activating a first function of the vehicle when the strength exceeds a first predefined threshold;
- and
- (k) activating a second function of the vehicle when the strength exceeds a second predefined threshold.
A method for controlling access to a vehicle which has a door and an engine, that method comprising the steps of:
- (a) periodically transmitting an interrogation signal at a given rate from a control circuit on the vehicle;
- (b) receiving the interrogation signal at a remote control that is separate from the vehicle;
- (c) upon receiving the interrogation signal, transmitting a reply signal from the remote control;
- (d) receiving the reply signal at the control circuit;
- (e) measuring strength of the reply signal at the control circuit;
- (f) activating a first function of the vehicle when the strength exceeds a first predefined threshold;
- (g) after activating the first function, changing the given rate at which the interrogation signal is transmitted, and repeating steps (a) through (e);
- and
- (h) thereafter activating a second function of the vehicle when the strength of the reply signal exceeds a second predefined threshold.
Dependencies are inferred from the claim text.