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Abstract

Methods for determining integrity of pseudorange and pseudorange rate signals received from a plurality of M Satellite Positioning System satellites (including GPS and GLONASS), numbered j=j1, j2, . . . , jM, at a reference SATPS station (RS), using pseudorange or pseudorange rate signals received from the same satellites at a nearby signal integrity monitoring (SIM) station. Pseudorange correction values or, alternatively, pseudorange rate correction values, for SATPS signals received at an RS station and at the corresponding SIM station are computed, and difference values between the RS and SIM values are computed for each satellite. If the magnitude of each difference is less than a selected threshold difference, pseudorange corrections or pseudorange rate corrections for that reference station can be used by a nearby mobile station to differentially correct the mobile station location fix coordinates or velocity fix coordinates. If N acceptable pairs of difference values are found for the pseudorange or pseudorange rate corrections, for particular satellites: clock bias or frequency offset can be corrected if N.gtoreq.1; accuracy of the clock bias or frequency offset coordinate can be monitored if N.gtoreq.2; and location fix coordinates or velocity fix coordinates can be corrected if N.gtoreq.3. If magnitudes of differences between measured and known location coordinates or velocity coordinates for the SIM station are less than threshold differences, pseudorange corrections or pseudorange rate corrections for that reference station can be used by a nearby mobile station to differentially correct the mobile station location fix coordinates or velocity fix coordinates.

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First Claim