Patent ID: 6337657
Filing Date: 2002-01-08
Classification: G01S

Abstract:
A method of generating a set of one or more refined estimates ({circumflex over (P)}fx,n, {circumflex over (P)}fy,n, {circumflex over (P)}fz,n, {circumflex over (P)}f&tgr;,n) for a selected set of one or more corresponding position-time components of a receiver of global positioning satellite signals for a moment of time tn, each position-time component of the selected set being one of the receiver's position coordinates or the receiver's time offset, each satellite signal being transmitted by a corresponding satellite and enabling the receiver to measure a pseudorange between itself and the corresponding satellite, said method comprising the steps of:(a) obtaining a set of one or more snapshot-solution values ({tilde over (P)}x,n, {tilde over (P)}y,n, {tilde over (P)}z,n, {tilde over (P)}&tgr;,n) for the selected set of one or more position-time components at the time moment tn, a corresponding snapshot-solution value being obtained for each position-time component in the selected set; (b) generating a set of one or more predicted values ({circumflex over (P)}â€²x,n, {circumflex over (P)}â€²y,n, {circumflex over (P)}â€²z,n, {circumflex over (P)}â€²&tgr;,n) for the selected set of one or more position-time components at the time moment tn, a corresponding predicted value being generated for each position-time component in the selected set, said predicted values being generated from a measurement of a plurality of satellite carrier phases over a time interval from a previous time moment tnâˆ’1 to the time moment tn and from a set of one or more values for the selected set of one or more position-time components at the previous time moment tnâˆ’1; (c) generating a first quality factor Qn which is representative of the accuracy of the set of one or more snapshot solution values; (d) generating a second quality factor Qnâ€² which is representative of the accuracy of the set of one or more predicted values; (e) generating said set of one or more refined estimates ({circumflex over (P)}fx,n, {circumflex over (P)}fy,n, {circumflex over (P)}fz,n, {circumflex over (P)}f&tgr;,n) for the corresponding selected position-time components as a first multiplier (&agr;n) of the set of the corresponding snapshot-solution values plus a second multiplier (1âˆ’&agr;n) of the set of the corresponding predicted values, with the sum of said first and second multipliers being equal to 1, wherein the first multiplier (&agr;n) is greater than the second multiplier (1âˆ’&agr;n) when the first and second quality factors indicate that the set of snapshot-solution values are more accurate than the set of predicted values, and wherein the second multiplier (1âˆ’&agr;n) is greater that the first multiplier (&agr;n) when the first and second quality factors indicate that the set of predicted values is more accurate than the set of snapshot-solution values.