Antitheft device for a motor vehicle and method for operating the antitheft device
US6218932A · kind A · utility
71Cited by
6References
8Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 16, 1999 |
| Grant date | Apr 17, 2001 |
| Priority date | — |
| Expiry date | Aug 16, 2019 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG07C2209/63
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
A first challenge signal whose reception power is measured in a portable code transmitter is transmitted by a vehicle-mounted transmission unit. Subsequently, a second challenge signal is transmitted under changed transmission conditions, and the reception power of the second challenge signal is also measured. Doors are unlocked, or the internal combustion engine is started only if the received power levels are also different. Otherwise, one or more challenge signals are transmitted once more under changed transmission conditions.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.