Multibeam position ambiguity resolution
First Claim
1. A method of distinguishing an actual position from an image position in a location determination system, said actual position being identified from first and second positions symmetrically located about a distinguishing line, and said method comprising the steps of:
- projecting a plurality of antenna beams in a plurality of diverse directions, wherein a first portion of said beams project on a first side of said distinguishing line and a second portion of said beams project on a second side of said distinguishing line;
receiving a signal transmitted through one of said beams; and
selecting, as said actual position, the one of said first and second positions which resides on the same side of said distinguishing line as the beam through which said signal was received.
3 Assignments
0 Petitions
Accused Products
Abstract
A radio telecommunications/location system includes a number of locator satellites in low earth orbits. The satellites include multibeam antennas. Locatable subscriber units communicate with the satellites. A single subscriber unit communicates with a single satellite using electromagnetic signals so that measurement processors can obtain Doppler component, and propagation duration measurements of the signals. A location processor converts these measurements into a two-position location solution. The two-position solution includes an actual position and an image position. The actual position may be detected in some situations by identifying a cell within which communications take place. In other situations, the actual position may be distinguished from the image position by comparing signals received at the subscriber unit through antenna beams projected to the left of the satellite'"'"'s ground track with signals received at the subscriber unit through antenna beams projected to the right of the satellite'"'"'s ground track.
47 Citations
20 Claims
-
1. A method of distinguishing an actual position from an image position in a location determination system, said actual position being identified from first and second positions symmetrically located about a distinguishing line, and said method comprising the steps of:
-
projecting a plurality of antenna beams in a plurality of diverse directions, wherein a first portion of said beams project on a first side of said distinguishing line and a second portion of said beams project on a second side of said distinguishing line; receiving a signal transmitted through one of said beams; and selecting, as said actual position, the one of said first and second positions which resides on the same side of said distinguishing line as the beam through which said signal was received. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
-
-
11. A method of operating a radio telecommunications system having a satellite moving in an orbit around the earth and having a subscriber unit located proximate the earth'"'"'s surface, said method comprising the steps of:
-
projecting a plurality of antenna beams in a plurality of diverse directions from said satellite, wherein a first portion of said beams project on a first side of a ground track for said satellite and a second portion of said beams project on a second side of said ground track; receiving, at one of said satellite and said subscriber unit, a signal transmitted through one of said beams; obtaining a set of location parameters which describe first and second possible positions of said subscriber unit; selecting, as an actual position for said subscriber unit, the one of said first and second possible positions which resides on the same side of said ground track as the beam through which said signal was received; and qualifying communication services provided for said subscriber unit in response to said actual position for said subscriber unit. - View Dependent Claims (12, 13, 14, 15, 16, 17)
-
-
18. A location determination system comprising:
-
at least one locator unit moving in an orbit around the earth, said movement causing a nadir direction of said locator unit to intersect the earth along a ground track for said locator unit, and said locator unit projecting a first plurality of beams toward the earth on a first side of said ground track and a second plurality of beams toward the earth on a second side of said ground track; at least one locatable unit residing proximate the earth'"'"'s surface; a measurement processor residing in one of said locator and locatable units, said measurement processor being configured to determine a Doppler component of an electromagnetic signal traveling between said locator and locatable units; and a location processor in data communication with said measurement processor, said location processor being configured to determine two positions for said locatable unit in response to said Doppler component, and said location processor comprising means for determining whether said electromagnetic signal was communicated through one of said first plurality of beams or through one of said second plurality of beams. - View Dependent Claims (19, 20)
-
Specification