Passive entry systems employing time of flight distance measurements

摘要

A passive entry method comprises: assessing at each satellite of a base station a signal quality of a test signal received by the satellite from a remote control 54; selecting by a controller of the base station the satellites having a higher signal quality than the remaining satellites 56; and conducting time of flight distance measurements with the remote control using the selected satellites 58. Each satellite may include an ultrawide band (UWB) transceiver and the remote control includes an UWB transceiver and assessing signal quality can be a measure of received signal strength intensity and/or may involve measuring noise level, first path signal power, or a ratio of the first path signal power to total signal power. The method may also include correcting the detected distance based on at least one of the measured noise level.