| 摘要 |
Methods and systems to determine the position of objects indoors or in confined areas are disclosed. A multitude of broadcast stations are transmitting an omni-directional reference signal and directional signals having each a phase-shift depending upon their specific direction. The objects whose positions are to be identified have a transponder and a means to measure the phase-shift between the omni-directional reference signal and a directional signal received. The measured time-difference indicating the relative direction to the broadcast station, which has sent the directional signal, is sent back to the broadcast station. The absolute position of the object can be determined by the results of an angular measurement of a second broadcast station. The broadcast stations can communicate amongst each other. A post-processing unit can initiate actions according to the position of an object identified.
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