Navigation system using external monitoring

• US 7,548,196 B2
• Filed: 02/15/2006
• Issued: 06/16/2009
• Est. Priority Date: 02/15/2005
• 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., Wen, Hengqing
• Primary Examiner(s): Tarcza; Thomas H
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US11/355,399
• Publication Number:
  US 20060214844A1
• Time in Patent Office: 1,217 Days
• Field of Search: 34235701-35717
• US Class Current: 342/357.21
• CPC Class Codes: G01S 19/071 DGPS corrections
• CPC Class Codes: G01S 19/08 providing integrity information, e.g. health of satellites or quality of ephemeris data

Abstract

A local area augmentation navigation system for determining the authenticity of the GPS signal. The system is provided with at least one reference station at a known location, a master station, a monitoring receiver, and a LAAS receiver. Each reference station receives a GPS signal from a GPS constellation and collects and outputs pseudo-range data from the GPS signal. The master station 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 station. The master station broadcasts the correction message. The monitoring receiver receives the GPS signal from the GPS constellation and the correction message to determine the accuracy of at least one of the broadcasted correction message and the GPS signal. The LAAS receiver receives the correction message broadcast by the master station as well as a GPS signal from the GPS constellation and 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 authenticity of the LAAS signal transmitted from a VDB transmitter, the system comprising:

at least one reference station at a known location, each reference station receiving a GPS signal from a GPS constellation and collecting and outputting pseudo-range data from the GPS signal;

a master station receiving the pseudo-range data from the at least one reference station, the master station forming a correction message from the pseudo-range data and the known location of the at least one reference station, the master station broadcasting the correction message;

at least one monitoring receiver at a known location receiving GPS signals from the GPS constellation and receiving the correction message broadcast by the master station;

wherein the monitoring receiver communicates with the master station to verify the authenticity of the correction message broadcast by the master station and monitor the OPS satellite integrity in field; 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, where in the monitoring receiver transmits received signals to an evaluation computer that evaluates signal accuracy.

3. The local area augmentation navigation system of claim 2, where in the evaluation computer issues an alert when an inaccurate signal is detected.

4. The local area augmentation navigation system of claim 2, where in the evaluation computer analyzes the GPS signal received by the monitoring receiver and issues an alert when an ionosphere turmoil is detected.

5. The local area augmentation navigation system of claim 2, where in the evaluation computer issues a correction message to the master station when an error is detected.

6. The local area augmentation navigation system of claim 2, where in the evaluation computer determines the GPS signal to be authentic and allows the continuation of the broadcast of the GPS signal.

7. The local area augmentation navigation system of claim 2, where in the evaluation computer includes at least one redundant backup system.

8. The local area augmentation navigation system of claim 1, where in the monitoring receiver includes at least one antenna that monitors GPS signal broadcasts in the area.

9. The local area augmentation navigation system of claim 1, where in the monitoring receiver includes at least one redundant backup monitoring receiver system.

10. The local area augmentation navigation system of claim 1, wherein the master station and the monitoring receiver communicate by at least one of a wireless and a cable connections.

11. The local area augmentation navigation system of claim 1, where in the monitoring receiver is able to detect an unauthentic signal or an ionosphere turmoil.

12. The local area augmentation navigation system of claim 1, where in the monitoring receiver is able to detect an unauthentic signal or an ionosphere turmoil and issue an alert.

13. The local area augmentation navigation system of claim 1, where in the monitoring receiver detects an unauthentic signal and instructs the broadcast of a GPS signal.

14. The local area augmentation navigation system of claim 1, where in the monitoring receiver detects an ionosphere turmoil and instructs the broadcast of a GPS signal.

15. The local area augmentation navigation system of claim 1, where in the monitoring receiver determines the GPS signal to be authentic and allows the continuation of the broadcast of the GPS signal or sends a correction message.

16. The local area augmentation navigation system of claim 1, where in the monitoring receiver monitors residual signal power.

17. The local area augmentation navigation system of claim 10, where in the monitoring receiver detects and above threshold increase in residual signal and accordingly issue an alert.

18. The local area augmentation navigation system of claim 1, where in the master station includes at least one antenna that monitors GPS signal broadcasts in the area.

19. The local area augmentation navigation system of claim 1, wherein the correction message broadcast is a LAAS VDB signal.

20. The local area augmentation navigation system of claim 19, where the monitoring receiver comprises:

at least one GPS receiver capable of receiving GPS signals from GPS satellites;

at least one VDB receiver capable of selectively receiving the correction message broadcast by the master station;

at least one communication link for communicating with the master station independent from the VDB receiver; and

,

a VDB transmitter capable of sending VDB signals to the LAAS receiver.

21. The local area augmentation navigation system of claim 20, wherein the monitoring receiver is capable of decoding the LAAS VDB signal and uses the decoded LAAS VDB signals and the digital correction message to verify the authenticity of the LAAS VDB signal.

22. The local area augmentation navigation system of claim 20, wherein the VDB receiver is capable of providing local LAAS VDB signal strength measurement.

23. The local area augmentation navigation system of claim 20, wherein the monitoring receiver uses LAAS VDB signal power to verify the authenticity of the LAAS VDB signal.

24. The local area augmentation navigation system of claim 20, wherein residual distribution of the LAAS VDB signal is used to verify the authenticity of the LAAS VDB signal.

25. The local area augmentation navigation system of claim 20, wherein residual power strength of the LAAS VDB signal is used to verify the authenticity of the LAAS VDB signal.

26. The local area augmentation navigation system of claim 20, wherein the monitoring receiver includes a processor for verifying the existence of intentional LAAS interference through the use of distribution pseudo-range correction provided in LAAS Type 1 messages.

27. The local area augmentation navigation system of claim 26, wherein the processor includes GPS observations, VDB observations, and digital LAAS messages from the master station to verify the authenticity of the LAAS VDB signal.

28. The local area augmentation navigation system of claim 20, wherein the VDB transmitter is capable of sending a stop message to the LAAS receiver for a user to cease using LAAS VDB signal broadcast for differential GPS application.

29. The local area augmentation navigation system of claim 1, wherein at least two monitoring receivers provide location and status of a LAAS or GPS interference source.