Passive remote access control system
US6570486B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 1999 |
| Grant date | May 27, 2003 |
| Priority date | — |
| Expiry date | Apr 9, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2209/63
- WIPO fieldControl
- WIPO sectorInstruments
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.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.