Passive RF-RF entry system for vehicles
US6396412B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Aug 17, 2001 |
| Grant date | May 28, 2002 |
| Priority date | — |
| Expiry date | Aug 17, 2021 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2209/63
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A system for preventing unauthorized access to a vehicle having a passive entry system uses a bi-directional radio frequency, or RF-RF, signal. When using a RF-RF signal system, the signal from vehicle to a driver's ID device is non-directional and not significantly distance limited. Consequently, a thief may be able to activate the entry system and gain access to the vehicle when the driver's ID device is simply within range. The inventive passive entry system interrogates the ID device periodically following parking and locking of the vehicle. The signal strength levels received by the vehicle from the ID device are stored and a signal strength threshold level is computed. Upon a request for entry to the vehicle, a current signal strength level is compared to the signal strength threshold level. Based on that comparison, it is determined whether the request is valid or unauthorized. If the request for entry is deemed unauthorized, then access to the vehicle is not granted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.