Patent ID: 7362265
Filing Date: 2008-04-22
Classification: G01S

Abstract:
1. A process for accurate location determination in an assisted GPS positioning system requiring at a minimum the transmission of data corresponding to ephemeris, satellite clock correction data, and approximate position information from an information source to the rover, the process comprising: (A1) using the signals from at least 5 satellites for 3-dimensional (3D) positioning or at least 4 satellites for 2-dimensional (2D) positioning; (B1) using pseudorange measurements in a system of equations having, as a minimum set of unknowns for 3D positioning the unknowns X, Y, Z, and T, where (X,Y,Z) is the 3D rover position in a predefined coordinate system, and T is the time at which simultaneous measurements are made to determine pseudoranges to all satellites; or (C1) using pseudorange measurements in a system of equations having, as a minimum set of unknowns for 2D positioning the unknowns X, Y, and T, where (X,Y) is the 2D horizontal rover position in a predefined coordinate system, and T is the time at which simultaneous measurements are made to determine pseudoranges to all satellites; (D1) where in said system of equations the position of each satellite is a vector-valued function ƒ further including a determination of accurate but ambiguous pseudorange differences by using the knowledge that the epochs of the GPS C/A pseudorandom code are transmitted at integer millisecond values of space vehicle (SV) time, which are corrected to GPS time using said satellite clock correction data.