Passive entry systems employing time of flight distance measurements

摘要

Systems and methods employ ultra-wide band (UWB) time of flight (ToF) distance measurements for locating a portable device relative to a target. Performance and reliability of UWB ToF distance measurements for locating the portable device is improved by adjusting a communication retry strategy based on signal quality calculations. The quality of an UWB signal received by each satellite of a base station is assessed based on factors like signal strength, noise level, and ratio of first path signal power to total signal power. This data is used to direct the retry strategy to the satellites receiving the best signal quality for these satellites to conduct ToF distance measurements with the portable device and/or to add correction factors to calculated ToF distance measurements.