Patent ID: 6281841
Filing Date: 2001-08-28
Classification: F41G,G01S

Abstract:
A method of determining direction in which an object is pointing, using a position locating system and at least two omnidirectional microwave antennas spaced apart by a predetermined distance on a chosen axis of said object comprising:(a) receiving at said antennas microwave signals from satellites at known positions,(b) phase shifting the signal from a first of said antennas through a range of phase angles,(c) summing the phase shifted signal with the signal from a second of said antennas,(d) extracting from the summed signal the signal from a first satellite using correlation techniques,(e) determining the magnitude of said signal from said first satellite as a function of the phase shift of the phase shifted signal,(f) determining the phase shift at peak magnitude,(g) calculating the angle between said first satellite and said object axis using the angle of phase shift and said predetermined spacing of the said two antennas,(h) resolving the ambiguity associated with the unknown integer number of complete cycles in the phase difference of the signals received by the two antennas;repeating steps (a) to (h) for signals from a second satellite to determine the angle between said second satellite and said object axis,deriving from said position locating system the ground position of the second antenna and the positions of said two satellites,calculating from the solid angles between each of said two satellites and the object axis, the positions of said satellites and the ground position of the second antenna, the two possible azimuth and elevational directions of the object axis, and resolving the ambiguity in direction by using directional information from another source.