Patent ID: 6829558
Filing Date: 2004-12-07
Classification: G01C

Abstract:
A method comprising the steps of:measuring a first set of coordinates of a device; measuring an estimated positional error (â€œEPEâ€ ) radius for the first set of coordinates; deriving an EPE circle representing a two-dimensional Cartesian plane, in which the device is approximately located, from the first set of coordinates and the EPE radius; determining that the EPE radius exceeds a predetermined threshold; measuring a first range between the device and a single ranging site; and determining a locus of points within the EPE circle, the locus of points representing a three-dimensional spherical coordinate system having an origin at a site intersecting the two-dimensional Cartesian plane, wherein a distance between the single ranging site and each point in the locus of points approximately equals the first range, the locus of points providing reduced position uncertainty for the device.