Mobile transmitting and receiving unit presence detecting arrangement for motor vehicle, has quasi-stable transmitting and receiving unit for changing preset time intervals between consecutive transmission of transmission signals

摘要

The arrangement has a quasi-stable transmitting and receiving unit (2) arranged in a vehicle (1). Transmitting antennas (3-5) wirelessly transmit signals (6-8) in different spatial effective ranges. A receiving antenna (18) wirelessly receives answer signals (9). A mobile transmitting and receiving unit (10) receives and transmits the signals (6-9). The quasi-stable transmitting and receiving unit changes preset time intervals between consecutive transmission of the transmission signals depending on distance between the mobile transmitting and receiving unit and the transmitting antennas. An independent claim is also included for a method for detecting presence of a mobile transmitting and receiving unit.