Patent ID: 7576693
Filing Date: 2009-08-18
Classification: G01S

Abstract:
1. A method to determine the position of one or more objects in a single plane comprising the steps of: providing a system comprising a multitude of broadcast stations broadcasting via antennas with a length in the order of 1.2 cm, communicating among each other and one or more objects whose positions are to be determined, wherein each of these objects has a transponder, an identifying code, and a means to measure phase shifts of signals; using the identifying code of each object whose position is to be determined as input in a nearest broadcast station; broadcasting inside or outside of buildings in a frequency range of 6 GHz from multiple broadcast stations an omni-directional reference signal and directional signals having each a phase shift characterizing their direction; calculating the directions of said object relative to at least two of said broadcast stations using the phase difference between the reference signal and one of said directional signals measured at the object's site; calculating the position of said object using the directions calculated in previous step; and displaying position of said object.