| 摘要 |
<p>A vehicle system 10 is provided with a portable device 12, such as a key fob, that is configured to provide a wireless signal. The system includes at least three base stations 16 positioned about a vehicle within a first plane (figure 4) and a fourth base station 14 positioned within the vehicle and vertically offset from the first plane to define a second plane (figure 5) with two of the at least three base stations. Each base station is configured to receive the wireless signal and to generate a message indicative of a time of flight of the wireless signal. The fourth base station is further configured to determine a three-dimensional location 20 of the portable device based on the message generated by each base station. The first and second planes may intersect, and the at least three base stations may be located in a vehicle headliner and the fourth base station within a dashboard. The location may be determined by trilateration, and the portable device may transmit a signal within a frequency of 3GHz and 10GHz. The system allows the location of a portable device to be determined so as to permit passive start or entry of the vehicle.</p> |
