diebstahlschutzeinrichtung for a vehicle and method for operating the diebstahlschutzeinrichtung

摘要

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.