| 摘要 |
An accurate location system 10 for use in locating the position of a tracked unit 16 having at least a first and a second transmitter 14, 22 for propagating at least first and second signals and a master station 12 for receiving and storing the first and second signals, respectively. The tracked unit 16 receives and operates on the first and second signals from the first and second transmitters 14, 22, respectively, for providing third and fourth signals which are transponded to the master station 12. A correlation detector 40 located within the master station 12 receives and cross-correlates the transponded third and fourth signals with the stored first and second signals within the master station for determining the additional times of flight ( tau ) of the third and fourth signals transponded to the master station. The locus of points of constant ( tau ) form an ellipse associated with each of the first and second signals with one of a plurality of intersections of the ellipses defining the position of the tracked unit 16. Thus, the invention provides a position location arrangement which receives and cross-correlates the direct and transponded signals to the master station to permit precisely locating the tracked unit by elliptical geometric methods.
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