System and method for generating precise code based and carrier phase position determinations

• US 5,583,513 A
• Filed: 10/13/1993
• Issued: 12/10/1996
• Est. Priority Date: 03/24/1993
• Status: Expired due to Fees

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: Cohen, Clark E.
• Primary Examiner(s): Issing, Gregory C.
• Application Number:
  US08/135,879
• Time in Patent Office: 1,154 Days
• Field of Search: 342/357, 342/385, 342/386, 342/458, 342/453, 342/464, 342/394, 342/353, 342/51, 342/33, 455/7, 455/11.1
• US Class Current: 342/357.42
• CPC Class Codes: G01S 19/04 providing carrier phase data
• CPC Class Codes: G01S 19/11 wherein the cooperating elements are pseudolites or satellite radio beacon positioning system signal repeaters
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 19/44 Carrier phase ambiguity resolution; Floating ambiguity; LAMBDA [Least-squares AMBiguity Decorrelation Adjustment] method

Abstract

A GPS system that includes a GPS beacon beacon that receives a plurality of GPS signals. Each of the GPS signals haa a carrier component and a pseudo-random code component. The beacon generates in response to the received GPS signals a plurality of beacon signals. Each of the plurality of beacon signals has a carrier component phase locked to one of the carrier components of the received GPS signals and a pseudo-random code component phase locked to one of the pseudo-random code components of the received GPS signals. The beacon then transmits the plurality of beacon signals. The system also includes a GPS receiver. The GPS receiver can make Code Based Differential GPS position determinations by making range measurements for each of the pseudo-random code components of the GPS and beacon signals and in response computing values representing a position. Additionally, the GPS receiver can make Carrrier Phase Differential GPS position determinations by first making phase measurements for each of the carrier components of the GPS and beacon signals at a plurality of measurment epochs during an initialization period. It then computes initialization values in response to these phase measurements for the GPS and beacon signals. Then, at a subsequent epoch after the initialization period, it computes a position in responsive to the initialization values and in response to the phase values for the GPS and beacon signals measured at the subsequent measurment epoch.

Claims

1. In a GPS system for making position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellite signals having a carrier component and a pseudo-random code component, said GPS system including a mobile GPS receiver system that receives the transmitted GPS satellite signals, a GPS beacon at a fixed known location with respect comprising:

receiving means for receiving GPS satellite signals each having a carrier component and a pseudo-random code component;

generating means for phase locking onto the carrier component and the pseudo-random code component of each of the GPS satellite signals received by the receiving means and for generating GPS beacon signals each having a carrier component and a pseudo-random code component respectively in phase with the phase locked onto carrier component and the phase locked onto pseudo-random code component of a corresponding one of the GPS satellite signals received by the receiving means; and

transmitting means for transmitting the generated GPS beacon signals so that the mobile GPS receiver system receives the transmitted GPS beacon signals and computes its position with respect to the reference coordinate system in response to the GPS satellite and GPS beacon signals it receives and the known location of the GPS beacon.

2. The GPS beacon of claim 1 wherein, for each respective one of the generated GPS beacon signals, the generating means includes:

a first phase locked loop to phase lock onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received by the receiving means and produce in response a pseudo-random code phase locking clock signal;

a second phase locked loop to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals and produce in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

a transmit pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a transmit pseudo random code in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals; and

circuitry to combine the transmit pseudo-random code component and the reconstructed carrier component and generate in response the respective one of the generated GPS beacon signals.

3. The GPS beacon of claim 2 wherein:

the first phase locked loop includes a receive pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a receive pseudo-random code component that is an in phase version of the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals;

the second phase locked loop is responsive to the receive pseudo-random code component to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals.

4. The GPS beacon of claim 1 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and the other ones of the GPS beacon signals.

5. In a GPS system for making position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellite signals having a carrier component and a pseudo-random code component, said GPS system including a mobile GPS receiver system that receives the transmitted GPS satellite signals, a method of generating GPS beacon signals at a fixed known location with respect to a reference coordinate system comprising the steps of:

receiving GPS satellite signals each having a carrier component and a pseudo-random code component;

phase locking onto the carrier component and the pseudo-random code component of each of the GPS satellite signals received in the receiving step and generating GPS beacon signals each having a carrier component and a pseudo-random code component respectively in phase with the phase locked onto carrier component and the phase locked onto pseudo-random code component of a corresponding one of the GPS satellite signals received in the receiving step; and

transmitting the generated GPS beacon signals so that the mobile GPS receiver system receives the transmitted GPS beacon signals and computes its position with respect to the reference coordinate system in response to the GPS satellite and beacon signals it receives and the known location.

6. The method of claim 5 wherein, for each respective one of the generated GPS beacon signals, the phase locking and generating step includes the steps of:

phase locking onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received in the receiving step and producing in response a pseudo-random code phase locking clock signal;

phase locking onto the carrier component of the respective corresponding one of the received GPS satellite signals and producing in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

generating a transmit pseudo random code in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal; and

combining the transmit pseudo-random code component and the reconstructed carrier component and generating in response the respective one of the generated GPS beacon signals.

7. The method of claim 6 wherein:

the step of phase locking onto the pseudo-random code component of the respective corresponding one of the received GPS satellite signals includes the step of generating a receive pseudo-random code component that is an in phase version of the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal;

the step of phase locking onto the carrier component of the respective corresponding one of the received GPS satellite signals is in response to the receive pseudo-random code component.

8. The method of claim 5 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

9. A GPS positioning system for making position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellite signals having a pseudo-random code component, the GPS positioning system comprising:

a GPS beacon positioned at a fixed known position with respect to a reference coordinate system, the GPS beacon including;

beacon receiving means for receiving the transmitted GPS satellite signals;

signal generating means for phase locking onto the pseudo-random code component of each of the GPS satellite signals received by the beacon receiving means and for generating GPS beacon signals each having a pseudo-random code component in phase with the phase locked onto pseudo-random code component of a corresponding one of the GPS satellite signals received by the beacon receiving means; and

transmitting means for transmitting the generated GPS beacon signals; and

a mobile GPS receiver system including;

mobile system receiving means for receiving the transmitted GPS satellite and beacon signals;

range measuring means for making at a measurement epoch range measurements for the pseudo random code components of the GPS satellite and beacon signals received by the mobile system receiving means;

means for determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epoch; and

position computing means for computing a precise position for the mobile GPS receiver system with respect to the reference coordinate system at the measurement epoch in response to the range measurements, the known location of the GPS beacon, and the determined directions to the GPS satellites.

10. The GPS positioning system of claim 9 wherein:

each of the GPS satellite and beacon signals also includes a carrier component; and

for each respective one of the generated GPS beacon signals, the signal generating means includes;

a first phase locked loop to phase lock onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received by the beacon receiving means and produce in response a pseudo-random code phase locking clock signal;

a second phase locked loop to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals and produce in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

a transmit pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a transmit pseudo random code component in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals; and

circuitry to combine the transmit pseudo-random code component and the reconstructed carrier component and generate in response the respective one of the generated GPS beacon signals.

11. The GPS positioning system of claim 9 wherein the position computing means computes the precise position for the mobile GPS receiver system based on a predefined set of simultaneous equations, each of the simultaneous equations relating (A) the precise position of the mobile GPS receiver system, (B) the range measurements for a respective one of the GPS satellite signals and a respective corresponding one of the GPS beacons signals, (C) the known location of the GPS beacon, and (D) the determined direction to the GPS satellite that transmits the respective one of the GPS satellite signals.

12. The GPS positioning system of claim 11 wherein:

the set of simultaneous equations comprises a set of non-linear equations that are linearized such that the precise position for the mobile GPS receiver system is represented by an estimate and a precise difference between the estimate and the precise position;

the mobile GPS receiver system further includes means to compute an initial guess position for the mobile GPS receiver system at the measurement epoch;

the position computing means iteratively computes the precise position (A) computing the precise difference in iterations based on the set of simultaneous linearized non-linear equations, (B) in a first one of the iterations, using the initial guess position as the estimate, (C) in each subsequent one of the iterations, using as the estimate the estimate used in a directly preceding one of the iterations adjusted by the precise difference computed in the directly preceding one of the iterations, and (D) after a final one of the iterations, using as the computed precise position the estimate used in the final one of the iterations adjusted by the precise difference computed in the final one of the iterations.

13. The GPS system of claim 9 further comprising a geosynchronous satellite transponder to receive the GPS beacon signals transmitted by the GPS beacon and re-transmit the GPS beacon signals to the mobile GPS receiver system.

14. The GPS positioning system of claim 9 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

15. A method of making GPS position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellites signals having a pseudo-random code component, the method comprising the steps of:

positioning a GPS beacon at a fixed known location with respect to a reference coordinate system;

with the GPS beacon;

receiving the transmitted GPS satellite signals;

phase locking onto the pseudo-random code component of each of the GPS satellite signals received with the GPS beacon and generating GPS beacon signals each having a pseudo-random code component in phase with the phase locked onto pseudo-random code component of a corresponding one of the GPS satellite signals received with the GPS beacon; and

transmitting the generated GPS beacon signals; and

with a mobile GPS receiver system;

receiving the transmitted GPS satellite and beacon signals;

making at a measurement epoch range measurements for the pseudo-random code components of the GPS satellite and beacon signals received with the mobile GPS receiver system;

determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epoch; and

computing a precise position for the mobile GPS receiver system at the measurement epoch in response to the range measurements, the known location of the GPS beacon, and the determined directions to the GPS satellites.

16. The method of claim 15 wherein:

each of the GPS satellite and beacon signals also includes a carrier component; and

for each respective one of the generated GPS beacon signals, the phase locking and generating step includes the steps of;

phase locking onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received with the GPS beacon and producing in response a pseudo-random code phase locking clock signal;

phase locking onto the carrier component of the respective corresponding one of the GPS satellite signals and producing in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

generating a transmit pseudo-random code component in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal; and

combining the transmit pseudo-random code component and the reconstructed carrier component to generate the respective one of the generated GPS beacon signals.

17. The method of claim 15 wherein the precise position for the mobile GPS receiver system is computed in the position computing step based on a predefined set of simultaneous equations, each of the simultaneous equations relating (A) the precise position of the mobile GPS receiver system, (B) the range measurements for a respective one of the GPS signals and a respective corresponding one of the GPS beacons signals, (C) the known location of the GPS beacon, and (D) the determined direction to the GPS satellite that transmits the respective one of the GPS satellite signals.

18. The method of claim 17 wherein:

the set of simultaneous equations comprises a set of non-linear equations that are linearized such that in each equation the precise position for the mobile GPS receiver system is represented by an estimate and a precise difference between the estimate and the precise position;

the method further comprises the step of computing, with the mobile GPS receiver system, an initial guess position for the mobile GPS receiver system at the measurement epoch;

the precise position is iteratively computed in the precise position computing step by (A) computing the precise difference in iterations based on the set of simultaneous linearized non-linear equations, (B) in a first one of the iterations, using the initial guess position as the estimate, and (C) in each subsequent one of the iterations, using as the estimate the estimate used in a directly preceding one of the iterations offset by the precise difference computed in the directly preceding one of the iterations, and (D) after a final one of the iterations, using as the computed precise position the estimate used in the final one of the iterations adjusted by the precise difference computed in the final one of the iterations.

19. The method of claim 15 further comprising the step of, with a geosynchronous satellite transponder, receiving the GPS beacon signals transmitted with the GPS beacon and re-transmitting the GPS beacon signals to the mobile GPS receiver system.

20. The method of claim 15 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

21. A GPS positioning system for making position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellite signals having a pseudo-random code component and a carrier component, the GPS positioning system comprising:

a GPS beacon positioned at a fixed known location with respect to a reference coordinate system, the GPS beacon including;

beacon receiving means for receiving the transmitted GPS satellite signals;

signal generating means for phase locking onto the pseudo-random code component and the carrier component of each of the GPS satellite signals received by the beacon receiving means and for generating GPS beacon signals each having a pseudo-random code component and a carrier component respectively in phase with the phase locked onto pseudo-random code component and the phase locked onto carrier component of a corresponding one of the GPS satellite signals received by the beacon receiving means; and

transmitting means for transmitting the generated GPS beacon signals; and

a mobile GPS receiver system including;

mobile system receiving means for receiving the transmitted GPS satellite and beacon signals;

computing means for computing a position for the mobile GPS receiver system with respect to the reference coordinate system in response to the GPS satellite and beacon signals received by the mobile system receiving means and the known location of the GPS beacon.

22. The GPS positioning system of claim 21 wherein, for each respective one of the generated GPS beacon signals, the signal generating means includes:

a first phase locked loop to phase lock onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received by the beacon receiving means and produce in response a pseudo-random code phase locking clock signal;

a second phase locked loop to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals and produce in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

a transmit pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a transmit pseudo random code in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals; and

circuitry to combine the transmit pseudo-random code component and the reconstructed carrier component and generate in response the respective one of the generated GPS beacon signals.

23. The GPS positioning system of claim 22 wherein:

the first phase locked loop includes a receive pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a receive pseudo-random code component that is an in phase version of the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals;

the second phase locked loop is responsive to the receive pseudo-random code component to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals.

24. The GPS positioning system of claim 21 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

25. A GPS system for resolving integer wavelength ambiguities associated with phase measurements for carrier components of GPS satellite signals transmitted by GPS satellites, the GPS system comprising:

one or more GPS beacons each positioned at a fixed known location with respect to a reference coordinate system, each of the one or more GPS beacons including;

beacon receiving means for receiving the transmitted GPS satellite signals;

signal generating means for phase locking onto the carrier component of each of the GPS satellite signals received by the beacon receiving means and for generating GPS beacon signals each having a carrier component in phase with the phase locked onto carrier component of a corresponding one of the GPS satellite signals received with the beacon receiving means; and

transmitting means for transmitting the generated GPS beacon signals; and

a mobile GPS receiver system including;

mobile system receiving means for receiving the transmitted GPS satellite and beacon signals;

phase measuring means for making at a plurality of measurement epochs phase measurements for the carrier components of each of the GPS satellite and beacon signals received by the mobile system receiving;

wherein for the phase measurements made for the carrier component of each of the GPS satellites, there is an associated integer wavelength ambiguity;

means for determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs; and

integer ambiguity resolution means for resolving the integer wavelength ambiguities in response to the phase measurements, the known location of each of the one or more GPS beacons, and the determined directions to the GPS satellites.

26. The GPS system of claim 25 wherein:

each of the GPS satellite and beacon signals also includes a pseudo-random code component; and

for each respective one of the GPS beacon signals generated by the signal generating means, the signal generating means includes;

a first phase locked loop to phase lock onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received by the beacon receiving means and produce in response a pseudo-random code phase locking clock signal;

a second phase locked loop to phase lock onto the carrier component of the respective corresponding one of the GPS satellite signals and produce in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

a transmit pseudo-random code generator, responsive to the pseudo-random code phase locking clock signal, to generate a transmit pseudo-random code component in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals; and

circuitry to combine the transmit pseudo-random code component and the reconstructed carrier component and generate in response the respective one of the GPS beacon signals.

27. The GPS system of claim 26 wherein the pseudo-random code component of the respective one of the generated GPS beacon signals is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

28. The mobile GPS receiver system of claim 25 wherein the phase measuring means makes the phase measurements during a period in which a large angular change in geometry occurs between the mobile GPS receiver system and the one or more GPS beacons.

29. The GPS system of claim 28 wherein the integer ambiguity resolution means resolves the integer wavelength ambiguities with batch processing of the phase measurements, the known location of each of the one or more GPS beacons, and the determined directions to the GPS satellites.

30. The GPS system of claim 29 wherein:

the mobile GPS receiver system has unknown precise positions with respect to the reference coordinate system at the measurement epochs;

the integer ambiguity resolution means resolves the integer wavelength ambiguities with the batch processing based on a predefined set of simultaneous equations, each of the equations relating (A) the unknown precise position of the mobile GPS receiver system at a corresponding one of the measurement epochs, (B) the phase measurements for a respective one of the GPS satellite signals and a respective corresponding one of the GPS beacon signals made at the corresponding measurement epoch, (C) the integer wavelength ambiguity associated with phase measurements for the respective one of the GPS satellite signals, (D) the known location of the one of the one or more GPS beacons that transmits the respective corresponding one of the GPS beacon signals, and (E) the determined direction to the one of the GPS satellites that transmits the respective one of the GPS satellite signals at the corresponding measurement epoch, wherein the number of the GPS satellite signals and the measurement epochs is such that the set of simultaneous equations is overdetermined.

31. The GPS system of claim 30 wherein:

the set of simultaneous equations comprises a set of non-linear equations that are linearized such that the unknown precise positions for the mobile GPS receiver system at the measurement epochs are represented by estimates and precise differences between the estimates and the unknown precise positions;

the mobile GPS receiver system further includes means for computing initial guess positions for the mobile GPS receiver system at the measurement epochs;

the integer ambiguity resolution means iteratively resolves the integer wavelength ambiguities with the batch processing by (A) resolving the integer wavelength ambiguities and computing the precise differences in iterations based on the set of simultaneous equations, (B) in a first one of the iterations, using the initial guess positions as the estimates, and (C) in each subsequent one of the iterations, using as the estimates the estimates used in a directly preceding one of the iterations adjusted by the precise differences computed in the directly preceding one of the iterations.

32. The GPS system of claim 25 wherein:

the mobile GPS receiver system is mounted on an aircraft on a final approach trajectory to a runway;

each of the one or more GPS beacons is positioned in front of the runway below the final approach trajectory of the aircraft;

the phase measuring means makes the phase measurements while the aircraft is on the final approach trajectory.

33. The GPS system of claim 32 wherein:

the final approach trajectory has an along track component;

the one or more GPS beacons comprises two GPS beacons further positioned on opposite sides of the along track component of the final approach trajectory.

34. A method of resolving integer wavelength ambiguities associated with phase measurements for carrier components of GPS satellite signals transmitted by GPS satellites, the method comprising the steps of:

positioning one or more GPS beacons each at known fixed location with respect to a reference coordinate system;

with each respective one of the one or more GPS beacons;

receiving the transmitted GPS satellite signals;

phase locking onto the carrier component of each of the GPS satellite signals received with the respective one of the one or more GPS beacons and generating GPS beacon signals each having a carrier component in phase with the phase locked onto carrier component of a corresponding one of the GPS satellite signals received with the respective one of the one or more GPS beacons; and

transmitting the generated GPS beacon signals; and

with a mobile GPS receiver system;

receiving the transmitted GPS satellite and beacon signals;

making at a plurality of measurement epochs phase measurements for the carrier components of the GPS satellite and beacon signals received with the mobile GPS receiver system;

wherein for the phase measurements made for the carrier component of each of the GPS satellite signals, there is an associated integer wavelength ambiguity;

determining directions to the GPS satellites with respect to the reference coordinate system at the measurement epochs;

resolving the integer wavelength ambiguities in response to the phase measurements, the known location of each of the one or more GPS beacons, and the determined directions to the GPS satellites.

35. The method of claim 34 wherein:

each of the GPS satellite and beacon signals also includes a pseudo-random code component; and

for each respective one of the GPS beacon signals generated with the respective one of the one or more GPS beacons, the phase locking and generating step with the respective one of the one or more GPS beacons includes the steps of;

phase locking onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received with the respective one of the one or more GPS beacons and producing in response a pseudo-random code phase locking clock signal;

phase locking onto the carrier component of the respective corresponding one of the GPS satellite signals and producing in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

generating a transmit pseudo-random code component in phase with the phase locked onto pseudo-random code component of the corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal; and

combining the transmit pseudo-random code component and the reconstructed carrier component and generating in response the respective one of the GPS beacon signals.

36. The method of claim 35 wherein the pseudo-random code component of the respective one of the generated GPS beacon signals is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.

37. The method of claim 34 wherein the phase measurements are made in the phase measuring step during a period in which a large angular change in geometry occurs between the mobile GPS receiver system and the one or more GPS beacons.

38. The method of claim 37 wherein the integer wavelength ambiguities are resolved in the resolving step with batch processing of the phase measurements, the known location of each of the one or more GPS beacons, and the determined directions to the GPS satellites.

39. The GPS system of claim 38 wherein:

the mobile GPS receiver system has unknown precise positions with respect to the reference coordinate system at the measurement epochs;

the integer wavelength ambiguities are resolved with the batch processing in the resolving step based on a predefined set of simultaneous equations, each of the equations relating (A) the unknown precise position of the mobile GPS receiver system at a corresponding one of the measurement epochs, (B) the phase measurements for a respective one of the GPS satellite signals and a respective corresponding one of the GPS beacon signals made at the corresponding measurement epoch, (C) the integer wavelength ambiguity associated with phase measurements for the respective one of the GPS satellite signals, (D) the known location of the one of the one or more GPS beacons that transmits the respective corresponding one of the GPS beacon signals, and (E) the determined direction to the one of the GPS satellites that transmits the respective one of the GPS satellite signals at the corresponding measurement epoch, wherein the number of the GPS satellite signals and the measurement epochs is such that the set of simultaneous equations is overdetermined.

40. The method of claim 39 wherein:

the set of simultaneous equations comprises a set of non-linear equations that are linearized such that the unknown precise positions for the mobile GPS receiver system at the measurement epochs are represented by estimates and precise differences between the estimates and the unknown precise positions;

the method further comprises the step of computing initial guess positions for the mobile GPS receiver system at the measurement epochs;

the integer wavelength ambiguities are iteratively resolved with the batch processing in the resolving step by (A) resolving the integer wavelength ambiguities and computing the precise differences in iterations based on the set of simultaneous equations, (B) in a first one of the iterations, using the initial guess positions as the estimates, and (C) in each subsequent one of the iterations, using as the estimates the estimates used in a directly preceding one of the iterations adjusted by the precise differences computed in the directly preceding one of the iterations.

41. The method of claim 34 wherein:

the mobile GPS receiver system is mounted on an aircraft on a final approach trajectory to a runway;

each of the one or more GPS beacons is positioned in the positioning step in front of the runway below the final approach trajectory of the aircraft.

42. The method of claim 41 wherein:

the final approach trajectory has an along track component;

the one or more GPS beacons comprise two GPS beacons; and

the two GPS beacons are further positioned in the positioning step on opposite sides of the along track component of the final approach trajectory.

43. A method of making GPS position determinations with GPS satellite signals transmitted by GPS satellites, each of the GPS satellite signals having a pseudo-random code component and a carrier component, the method comprising the steps of:

positioning a GPS beacon at a fixed known location with respect to a reference coordinate system;

with the GPS beacon;

receiving the transmitted GPS satellite signals;

phase locking onto the pseudo-random code component and the carrier component of each of the GPS satellite signals received with the GPS beacon and generating GPS beacon signals each having a pseudo-random code component and a carrier component respectively in phase with the phase locked onto pseudo-random code component and the phase locked onto carrier component of a corresponding one of the GPS satellite signals received with the GPS beacon; and

transmitting the generated GPS beacon signals; and

with a mobile GPS receiver system;

receiving the transmitted GPS satellite and beacon signals;

computing a position for the mobile GPS receiver system with respect to the reference coordinate system in response to the GPS satellite and beacon signals received with the mobile GPS receiver system and the known location of the GPS beacon.

44. The method of claim 43 wherein, for each respective one of the generated GPS beacon signals, the phase locking and generating step includes the steps of:

phase locking onto the pseudo-random code component of a respective corresponding one of the GPS satellite signals received with the GPS beacon and producing in response a pseudo-random code phase locking clock signal;

phase locking onto the carrier component of the respective corresponding one of the GPS satellite signals and producing in response a reconstructed carrier component that is an in phase version of the phase locked onto carrier component of the respective corresponding one of the GPS satellite signals;

generating a transmit pseudo random code in phase with the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal; and

combining the transmit pseudo-random code component and the reconstructed carrier component and generating in response the respective one of the generated GPS beacon signals.

45. The method of claim 44 wherein:

the step of phase locking onto the pseudo-random code component of the respective corresponding one of the GPS satellite signals includes the step of generating a receive pseudo-random code component that is an in phase version of the phase locked onto pseudo-random code component of the respective corresponding one of the GPS satellite signals in response to the pseudo-random code phase locking clock signal;

the step of phase locking onto the carrier component of the respective corresponding one of the GPS satellite signals is in response to the receive pseudo-random code component.

46. The method of claim 43 wherein the pseudo-random code component of each GPS beacon is unique from the pseudo-random code components of the GPS satellite signals and all other ones of the GPS beacon signals.