Patent ID: 6271788
Filing Date: 2001-08-07
Classification: G01S

Abstract:
A system for determining a position of an object, said system receiving position signals from a plurality of position units at known locations, each said position unit having a clock with a known clock bias and a known clock drift, said system comprising:a plurality of ground transmitters, each of said plurality of ground transmitters being configured to generate ground transmitter position signals that provide position information to the object, each of said plurality of ground transmitters including a clock with an unknown clock bias and an unknown clock drift, and each of said plurality of ground transmitters having a known position; anda base station configured to receive said position signals from each said position units, said base station being further configured to receive said ground transmitter position signals from each of said plurality of ground transmitters, said base station having an unknown clock bias, an unknown clock drift, and a known position, and said base station being further configured to calculate a differential correction data signal based on said position signals and said ground transmitter position signals and to transmit the differential correction data signal to said object; andwherein said object receives the position signals from each of said plurality of positioning units, the ground transmitter position signals from each of said ground transmitters, and the differential correction data signal from said base station, said object calculating its position based on said received signals.