Network for carrier phase differential GPS corrections

Claim 1

A method of providing GPS pseudorange and carrier phase correction information over a selected geographic region S with a diameter of up to about 3000 km with an associated inaccuracy as low as 5 cm, to provide increased accuracy for a GPS user in moving from a first selected location A to a second selected location B, the method comprising the steps of: (1) providing N spaced apart GPS fiducial stations, numbered n=1, 2, . . . , N (N≧3), whose location coordinates (u n ,v n ,w n ) in a selected coordinate system are fixed and known with high accuracy, within the region S; (2) causing each fiducial station to receive GPS information signals including pseudorange information and carrier phase information from M GPS satellites, numbered m=1, 2, . . . , M (M≧3), to compute the GPS-determined location of that fiducial station, to compute pseudorange corrections PRC(t;t0;m;n) at a selected time t0, which are valid for times t≧t0 that are near t0 and which reconcile the GPS-determined location with the known location of fiducial station number n using GPS signals received from satellite number m, to compute cumulative carrier phase correction signals χ(t;t0;m;n) corresponding to receipt at fiducial station number n of GPS carrier phase information from satellite number m, and to broadcast these pseudorange correction signals and carrier phase correction signals; (3) providing a GPS user with a mobile GPS station within the region S, which has stored within the station the coordinates (u',v',w') of an estimated present location vector u' of that mobile station and the spatial coordinates (u n (k), v n (k), w n (k)) (k=1, 2, . . . , K; K≧3) of K GPS fiducial stations with corresponding location vectors u n (k) within S that form a bounding polygon for the estimated present location of that mobile station, where the mobile station receives at least one of (i) a set of pseudorange signals PR(t;t0;m;mobile) and (ii) a set of carrier phase signals Φ(t;t0;m;mobile) from the GPS satellites and receives at least one of (i) a set of pseudorange correction signals PRC(t;t0;m;n) (m=1, . . . , M) and (ii) a set of carrier phase correction signals χ(t;t0;m;n) from the fiducial stations number n=n(k) (k=1,2, . . . , K), where the GPS user is to move from a first selected location A to a second selected location B; (4) selecting coefficients a k ' that minimizes the norm of the vector difference ##EQU6## under the constraint a 1 '+a 2 '+ . . . +a K '=1, with -0.5≦a k '≦1.5, for a selected number p>0; (5) determining at least one of (1) a set of pseudorange corrections and for that mobile station at its present location by the relations ##EQU7## and (2) a set of carrier phase correction signals for that mobile station at its present location by the relations ##EQU8## (6) computing at least one of (1) a set of corrected pseudorange signals for this mobile station, using the relations ##EQU9## and (2) a set of corrected carrier phase signals Φ for this mobile station, using the relations ##EQU10## (7) using at least one of (1) the set of corrected pseudorange signals PR(t;t0;m;mobile;corr) and (2) the set of corrected carrier phase signals Φ(t;t0;m;mobile;corr) to determine a corrected present location of this mobile station and to replace the estimated present location by the corrected present location of this mobile station; and (8) displaying at least one corrected present location of this mobile station for an estimated mobile station location that is distinct from the locations A and B.

Claim 2

A method of providing GPS pseudorange and carrier phase correction information over a selected geographic region S with a diameter of up to about 3000 km with an associated inaccuracy as low as 5 cm, to provide increased accuracy for a GPS user in moving from a first selected location A to a second selected location B, the method comprising the steps of: (1) providing N spaced apart GPS fiducial stations, numbered n=1, 2, . . . , N (N≧3), whose location coordinates (u n ,v n ,w n ) in a selected coordinate system are fixed and known with high accuracy, within the region S; (2) causing each fiducial station to receive GPS information signals including pseudorange information and carrier phase information from M GPS satellites, numbered m=1, 2, . . . , M (M≧3), to compute the GPS-determined location of that fiducial station, to compute pseudorange corrections PRC(t;t0;m;n) at a selected time t0, which are valid for times t≧t0 that are near t0 and which reconcile the GPS-determined location with the known location of fiducial station number n using GPS signals received from satellite number m, to compute cumulative carrier phase correction signals χ(t;t0;m;n) corresponding to receipt at fiducial station number n of GPS carrier phase information from satellite number m, and to broadcast these pseudorange correction signals and carrier phase correction signals; (3) providing a GPS user with a mobile GPS station within the region S, which has stored within the station the coordinates (u',v',w') of an estimated present location vector u' of that mobile station and the spatial coordinates (u n (k), v n (k), w n (k)) (k=1, 2, . . . , K; K≧3) of K GPS fiducial stations with corresponding location vectors u n (k) within S that form a bounding polygon for the estimated present location of that mobile station, where the mobile station receives at least one of (i) a set of pseudorange signals PR(t;t0;m;mobile) and (ii) a set of carrier phase signals Φ(t;t0;m;mobile) from the GPS satellites and receives at least one of (i) a set of pseudorange correction signals PRC(t;t0;m;n) (m=1, . . . , M) and (ii) a set of carrier phase correction signals χ(t;t0;m;n) from the fiducial stations number n=n(k) (k=1,2, . . . , K), where the GPS user is to move from a first selected location A to a second selected location B; (4) selecting coefficients a k ' that minimizes the norm of the vector difference ##EQU6## under the constraint a 1 '+a 2 '+ . . . +a K '=1, with -0.5≦a k '≦1.5, for a selected number p>0; (5) determining at least one of (1) a set of pseudorange corrections and for that mobile station at its present location by the relations ##EQU7## and (2) a set of carrier phase correction signals for that mobile station at its present location by the relations ##EQU8## (6) computing at least one of (1) a set of corrected pseudorange signals for this mobile station, using the relations ##EQU9## and (2) a set of corrected carrier phase signals Φ for this mobile station, using the relations ##EQU10## (7) using at least one of (1) the set of corrected pseudorange signals PR(t;t0;m;mobile;corr) and (2) the set of corrected carrier phase signals Φ(t;t0;m;mobile;corr) to determine a corrected present location of this mobile station and to replace the estimated present location by the corrected present location of this mobile station; and (8) displaying at least one corrected present location of this mobile station for an estimated mobile station location that is distinct from the locations A and B.

Claim 10

A method of providing GPS pseudorange correction and carrier phase correction information over a selected geographic region S with a diameter of up to about 200 km with an associated inaccuracy as low as 5 cm, to provide increased accuracy for a GPS user in moving from a first selected location A to a second selected location B, the method comprising the steps of: (1) providing N spaced apart GPS fiducial stations, numbered n=1, 2, . . . , N (N≧3), whose location coordinates (u n ,v n ,w n ) in a selected coordinate system are fixed and known with high accuracy, within the region S (2) causing each fiducial station to receive GPS signals from M GPS satellites, numbered m=1, 2, . . . , M (M≧3), to resolve carrier phase integer ambiguities associated with that fiducial station, and to transmit GPS information signals, including pseudorange and carrier phase information received from these satellites; (3) providing a central station, associated with the region S, that receives the GPS information signals transmitted by at least three fiducial stations within the region S, computes the GPS pseudorange corrections PRC(t;t0;m;n) at a selected time t0, which are valid for times t≧t0 that are near t0 and which reconcile the GPS-determined location with the known location of fiducial station number n using GPS signals received from satellite number m; (4) providing a GPS user with a mobile GPS station within the region S that has stored within it the coordinates (u',v',w') of an estimated present location of that mobile station, where the mobile station receives GPS signals from the GPS satellites and estimates its present location and receives signals transmitted by the central station, where the GPS user is to move from a first selected location A to a second selected location B; (5) causing the central station to compute parameters c hjk (m) that allow determination of total pseudorange corrections TPRC(t;t0;m;u,v,w), that approximate the pseudorange corrections valid at each fiducial station and are given by the relations ##EQU12## for a station whose coordinates are (u,v,w), where the parameters c hjk (m) are chosen to minimize a selected error associated with use of the total pseudorange corrections and (u0,v0,w0) are selected location coordinates; (6) causing the central station to broadcast at least one of the parameters c hjk (m); (7) causing the mobile station to receive the information on the parameters c hjk (m) from the central station, and to compute the pseudorange corrections and to compute corrected pseudorange signals applicable to the estimated location of the mobile station; (8) using the corrected pseudorange signals to compute a corrected present location of this mobile station and to replace the estimated present location of this mobile station by the corrected present location; and (9) displaying at least one corrected present location of this mobile station for an estimated mobile station location that is distinct from the locations A and B.

Claim 11

A method of providing GPS pseudorange correction and carrier phase correction information over a selected geographic region S with a diameter of up to about 200 km with an associated inaccuracy as low as 5 cm, to provide increased accuracy for a GPS user in moving from a first selected location A to a second selected location B, the method comprising the steps of: (1) providing N spaced apart GPS fiducial stations, numbered n=1, 2, . . . , N (N≧3), whose location coordinates (u n ,v n ,w n ) in a selected coordinate system are fixed and known with high accuracy, within the region S (2) causing each fiducial station to receive GPS signals from M GPS satellites, numbered m=1, 2, . . . , M (M≧3), to resolve carrier phase integer ambiguities associated with that fiducial station, and to transmit GPS information signals, including pseudorange and carrier phase information received from these satellites; (3) providing a central station, associated with the region S, that receives the GPS information signals transmitted by at least three fiducial stations within the region S, computes the GPS pseudorange corrections PRC(t;t0;m;n) at a selected time t0, which are valid for times t≧t0 that are near t0 and which reconcile the GPS-determined location with the known location of fiducial station number n using GPS signals received from satellite number m; (4) providing a GPS user with a mobile GPS station within the region S that has stored within it the coordinates (u',v',w') of an estimated present location of that mobile station, where the mobile station receives GPS signals from the GPS satellites and estimates its present location and receives signals transmitted by the central station, where the GPS user is to move from a first selected location A to a second selected location B; (5) causing the central station to compute parameters c hjk (m) that allow determination of total pseudorange corrections TPRC(t;t0;m;u,v,w), that approximate the pseudorange corrections valid at each fiducial station and are given by the relations ##EQU12## for a station whose coordinates are (u,v,w), where the parameters c hjk (m) are chosen to minimize a selected error associated with use of the total pseudorange corrections and (u0,v0,w0) are selected location coordinates; (6) causing the central station to broadcast at least one of the parameters c hjk (m); (7) causing the mobile station to receive the information on the parameters c hjk (m) from the central station, and to compute the pseudorange corrections and to compute corrected pseudorange signals applicable to the estimated location of the mobile station; (8) using the corrected pseudorange signals to compute a corrected present location of this mobile station and to replace the estimated present location of this mobile station by the corrected present location; and (9) displaying at least one corrected present location of this mobile station for an estimated mobile station location that is distinct from the locations A and B.