Navigation system using locally augmented GPS

• US 7,164,383 B2
• Filed: 09/24/2003
• Issued: 01/16/2007
• Est. Priority Date: 09/25/2002
• Status: Expired due to Fees

• Current Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Original Assignee: The Board of Regents of the University of Colorado (University of Colorado System)
• Inventors: Fagan, John E., Pendergraft, Rick, Wen, Hengquin
• Primary Examiner(s): Issing; Gregory C.
• Application Number:
  US10/669,614
• Publication Number:
  US 20040119638A1
• Time in Patent Office: 1,210 Days
• Field of Search: 342/357.02, 342/357.03, 342/357.1, 342/173
• US Class Current: 342/357.21
• CPC Class Codes: G01S 19/07 providing data for correcting measured positioning data, e.g. DGPS [differential GPS] or ionosphere corrections
• CPC Class Codes: G01S 19/15 Aircraft landing systems
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/23 Testing, monitoring, correcting or calibrating of receiver elements
• CPC Class Codes: G01S 19/41 Differential correction, e.g. DGPS [differential GPS]
• CPC Class Codes: G01S 5/009 Transmission of differential positioning data to mobile

Abstract

A local area augmentation navigation system for determining the location of an object using differential GPS. The system does not require any significant power or communication infrastructure. The system includes at least three reference stations, a master station and a LAAS receiver. The at least three reference stations are located in close proximity to each other and at known locations. Each of the reference stations receive a GPS signal from a GPS constellation and collect and output via a wireless transceiver the pseudo-range data from the GPS signal. The master station is positioned in close proximity to the reference stations and receives the pseudo-range data from the reference stations. The master station forms a correction message from the pseudo-range data and the known locations of the reference stations. The master station broadcasts the correction message within a specified area. The LAAS receiver is positioned within the specified area and receives the correction message broadcast by the master station as well as a GPS signal from the GPS constellation. The LAAS receiver calculates the location of the LAAS receiver with the correction message and the GPS signal.

Claims

1. A local area augmentation navigation system for determining the location of an object using differential GPS, the system comprising:

at least two reference stations at known locations, each of the reference stations receiving a GPS signal from a GPS constellation and collecting and outputting the pseudo-range data from the GPS signal;

a master station receiving the pseudo-range data from the reference stations, the master station forming a correction message from the pseudo-range data and the known locations of the reference stations, the master station broadcasting the correction message;

a security receiver and an evaluation computer cooperating to monitor the broadcast of the correction message by the master station, to also monitor other broadcasts in the area for unauthorized broadcasts having a similar character as the correction message broadcast by the master station, and to output an alert signal upon detection of an unauthorized broadcast, the security receiver receiving the correction message broadcast by the master station via a first communication link, wherein the evaluation computer receives the correction message output by the master station via a second communication link different from the first communication link and determines that an unauthorized broadcaster exists when the message received by the security receiver does not match the correction message broadcast by the master station; and

a LAAS receiver receiving the correction message broadcast by the master station as well as a GPS signal from the GPS constellation and calculating the location of the LAAS receiver with the correction message and the GPS signal.

2. The local area augmentation navigation system of claim 1, wherein the master station includes a VHF transmitter and broadcasts the correction message with the VHF transmitter.

3. The local area augmentation navigation system of claim 1, wherein the known locations of the reference stations are precisely surveyed locations.

4. The local area augmentation navigation system of claim 1, wherein each of the reference stations includes an independent power supply.

5. The local area augmentation navigation system of claim 4, wherein the independent power supply is a solar power supply.

6. The local area augmentation navigation system of claim 1, wherein the local area augmentation navigation system does not require any external significant power or communication infrastructure.

7. The local area augmentation navigation system of claim 1, wherein the correction message is broadcast as an omni directional data broadcast.

8. The local area augmentation navigation system of claim 1, wherein the correction message is broadcast as a directional data broadcast.

9. The local area augmentation navigation system of claim 1, wherein the object is an airplane, and wherein the correction message includes differential pseudo-range corrections and data describing the final approach paths that are available to the pilot.

10. The local area augmentation system of claim 1, wherein the evaluation computer is implemented in the security receiver.

11. The local area augmentation system of claim 1, wherein the evaluation computer is implemented in the master station.

12. The local area augmentation system of claim 1, wherein the evaluation computer is implemented in an air traffic control computer.

13. The local area augmentation system of claim 1, wherein the reference stations communicate with the master station via wireless transceivers.

14. The local area augmentation system of claim 1, wherein the communication between the reference stations and the master station is encoded.

15. A local area augmentation navigation system for determining the location of an object using differential GPS, the system comprising:

at least two reference stations at known locations, each of the reference stations receiving a GPS signal from a GPS constellation and collecting and outputting the pseudo-range data from the GPS signal;

a master station receiving the pseudo-range data from the reference stations, the master station forming a correction message from the pseudo-range data and the known locations of the reference stations, the master station broadcasting the correction message;

a security receiver and an evaluation computer cooperating to monitoring the broadcast of the correction message by the master station, to also monitor other broadcasts in the area for unauthorized broadcasts having a similar character as the correction message broadcast by the master station, and to output an alert signal upon detection of an unauthorized broadcast, the security receiver having an antenna separate from the master station, the security receiver receiving the correction message broadcast by the master station via a first communication link, and wherein the evaluation computer receives the correction message output by the master station via a second communication link different from the first communication link and determines that an unauthorized broadcaster exists when the message received by the security receiver does not match the correction message broadcast by the master station; and

a LAAS receiver receiving the correction message broadcast by the master station as well as a GPS signal from the GPS constellation and calculating the location of the LAAS receiver with the correction message and the GPS signal.

16. The local area augmentation navigation system of claim 15, wherein the master station includes a VHF transmitter and broadcasts the correction message with the VHF transmitter.

17. The local area augmentation navigation system of claim 15, wherein the known locations of the reference stations are precisely surveyed locations.

18. The local area augmentation navigation system of claim 15, wherein each of the reference stations includes an independent power supply.

19. The local area augmentation navigation system of claim 18, wherein the independent power supply is a solar power supply.

20. The local area augmentation navigation system of claim 15, wherein the local area augmentation navigation system does not require any external power or communication infrastructure.

21. The local area augmentation navigation system of claim 15, wherein the correction message is broadcast as an omni directional data broadcast.

22. The local area augmentation navigation system of claim 15, wherein the correction message is broadcast as a directional data broadcast.

23. The local area augmentation navigation system of claim 15, wherein the object is an airplane, and wherein the correction message includes differential pseudo-range corrections and data describing the final approach paths that are available to the pilot.

24. The local area augmentation system of claim 15, wherein the evaluation computer is implemented in the security receiver.

25. The local area augmentation system of claim 15, wherein the evaluation computer is implemented in the master station.

26. The local area augmentation system of claim 15, wherein the evaluation computer is implemented in an air traffic control computer.

27. The local area augmentation system of claim 15, wherein the reference stations communicate with the master station via wireless transceivers.

28. The local area augmentation system of claim 15, wherein the communication between the reference stations and the master station is encoded.

29. A local area augmentation navigation system for determining the location of an object using differential GPS, the system comprising:

at least two reference stations at known locations, each of the reference stations receiving a GPS signal from a GPS constellation and collecting and outputting the pseudo-range data from the GPS signal;

a master station receiving the pseudo-range data from the reference stations, the master station forming a correction message from the pseudo-range data and the known locations of the reference stations, the master station broadcasting the correction message;

a security receiver and an evaluation computer cooperating to monitor the broadcast of the correction message by the master station, to also monitor other broadcasts in the area for unauthorized broadcasts having a similar character as the correction message broadcast by the master station, and to output an alert signal upon detection of an unauthorized broadcast, the security receiver positioned remotely from the master station, the security receiver receiving the correction message broadcast by the master station via a first communication link, and wherein the evaluation computer receives the correction message output by the master station via a second communication link different from the first communication link and determines that an unauthorized broadcaster exists when the message received by the security receiver does not match the correction message broadcast by the master station; and

a LAAS receiver receiving the correction message broadcast by the master station as well as a GPS signal from the GPS constellation and calculating the location of the LAAS receiver with the correction message and the GPS signal.

30. The local area augmentation navigation system of claim 29, wherein the master station includes a VHF transmitter and broadcasts the correction message with the VHF transmitter.

31. The local area augmentation navigation system of claim 29, wherein the known locations of the reference stations are precisely surveyed locations.

32. The local area augmentation navigation system of claim 29, wherein each of the reference stations includes an independent power supply.

33. The local area augmentation navigation system of claim 32, wherein the independent power supply is a solar power supply.

34. The local area augmentation navigation system of claim 29, wherein the local area augmentation navigation system does not require any external power or communication infrastructure.

35. The local area augmentation navigation system of claim 29, wherein the correction message is broadcast as an omni directional data broadcast.

36. The local area augmentation navigation system of claim 29, wherein the correction message is broadcast as a directional data broadcast.

37. The local area augmentation navigation system of claim 29, wherein the object is an airplane, and wherein the correction message includes differential pseudo-range corrections and data describing the final approach paths that are available to the pilot.

38. The local area augmentation system of claim 29, wherein the evaluation computer is implemented in the security receiver.

39. The local area augmentation system of claim 29, wherein the evaluation computer is implemented in the master station.

40. The local area augmentation system of claim 29, wherein the evaluation computer is implemented in an air traffic control computer.

41. The local area augmentation system of claim 29, wherein the reference stations communicate with the master station via wireless transceivers.

42. The local area augmentation system of claim 29, wherein the communication between the reference stations and the master station is encoded.

43. A method for enhancing the security of a broadcast of a correction message between a master station of a local area augmentation system and a LAAS receiver, comprising the step of:

monitoring the broadcast between the master station of the local area augmentation system and the LAAS receiver for unauthorized broadcasts in the area having a similar character as the correction message broadcast by the master station using a security receiver and an evaluation computer;

receiving the correction message output by the master station via a first communication link by the security receiver and a second communication link by the evaluation computer; and

outputting an alert signal when the message received by the security receiver and evaluation computer does not match the correction message broadcast by the master station.