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Abstract

A method for enhancing the accuracy of location coordinates and/or clock bias computed for a mobile user station that is part of a Satellite Positioning System (SATPS), such as GPS or GLONASS. A reference SATPS station is provided with known location coordinates, and pseudoranges PR(t) and pseudorange corrections .DELTA.PR(t) for the reference station are computed as in a conventional differential GPS approach. A matrix equation H(t) .DELTA.W(t)=.DELTA.PR(t) relates the corrections for the spatial location coordinates and clock bias at the mobile station (or at the reference station) to the pseudorange correction values at that station, where H is an M.times.N matrix (M.ltoreq.N; N=3 or 4) with known entries. Each of the N rows of the matrix H has M entries and forms a row vector, and these row vectors are linearly independent in an M-dimensional vector space. These row vectors span an N-dimensional vector space. The matrix H is augmented by M-N rows representing independent vectors in an M-dimensional vector space, to produce an augmented M.times.M matrix H*, for which an inverse H*(t).sup.-1 exists. An augmented matrix equation .DELTA.W*(t;mobile)=H*(t).sup.-1 .DELTA.PR(t) is formed, and N of the entries in the M.times.1 matrix .DELTA.W*(t) are interpreted as corrections for the spatial location coordinates and/or clock bias for the mobile station. In another embodiment, an M.times.1 projected vector v is formed from all the uncorrected pseudorange components for the mobile station and a reduced set of these components are transmitted to the reference station. The full vector v is then reconstructed from this reduced set and used to reconstruct the mobile station uncorrected pseudorange values. Corrected mobile station pseudorange values are computed and used to determine the spatial location and clock bias coordinates for the mobile station.

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First Claim