| 摘要 |
A system for determining the location of portable communication devices such as cellular telephones and the like has multiple small, dedicated multipath calibration transponders at known positions. When a portable communication device initiates a call, base stations in the coverage area direct the transponders to generate response signals which are received by the base stations. The characteristics of the signals from the portable device and the transponders are provided to a base station controller linked to the base stations. The base station controller derives a coarse position using the raw device position information and uses the raw transponder position information and the transponder's known positions to derive a correction vector representative of multipath distortion of transponder signals in the area of the portable device. Since the portable device will generally experience the same distortion as the transponders in its area, the correction vector can be applied to the coarse device position to obtain its true position.
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