System and method for detecting interference in global positioning satellite signals

• US 7,512,492 B2
• Filed: 10/15/2002
• Issued: 03/31/2009
• Est. Priority Date: 04/13/2001
• Status: Active Grant

• Current Assignee: General Dynamics Mission Systems Inc. (General Dynamics Corporation)
• Original Assignee: General Dynamics Advanced Information Systems Incorporated (General Dynamics Corporation)
• Inventors: Gerten, Greg, Irvin, Dean, Sweetapple, Lee
• Primary Examiner(s): ARTHUR JEANGLAUDE, GERTRUDE
• Application Number:
  US10/270,236
• Publication Number:
  US 20030114983A1
• Time in Patent Office: 2,359 Days
• Field of Search: 701213-216, 342/357.06, 342/357.09, 342/357.1, 342/358
• US Class Current: 701/213
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service

Abstract

A system and method are provided for detecting local interference in GPS signals. A plurality of remotely located GPS receivers are capable of receiving GPS signals and producing GPS related data. A monitoring station is capable of storing at least one expected GPS parameter for each of the plurality of GPS receivers. A first processor at the monitoring station is programmed to determine, for each of the GPS receivers, whether said GPS related data deviates from any of the at least one GPS parameter by more than a predetermined range of error, and for issuing a warning in response thereto.

Claims

1. A system for detecting the location of a signal source, said system comprising:

a first GPS receiver configured to receive a GPS-related information;

a first processing system configured to calculate a derived GPS parameter from at least the GPS-related information and compare the derived GPS parameter and an expected GPS parameter;

a first sensor configured to detect first information of the signal source;

a second processing system configured to calculate, from at least the first information, data representing a probable location of the source of the signal; and

a user interface configured to display the data;

wherein the user interface displays the data in response to the first processing system determining that the derived GPS parameter and the expected GPS parameter differ by at least a predetermined amount.

2. The system of claim 1 wherein said first processing system comprises a first processor at a remote location configured to calculate the derived GPS parameter from at least the GPS-related information and a second processor at a monitoring unit configured to compare the derived GPS parameter and the expected GPS parameter.

3. The system of claim 1 further comprising:

a second GPS receiver configured to receive second GPS-related information;

a third processing system configured to calculate second derived GPS parameter from at least the second GPS-related information; and

a second sensor configured to detect second information of the signal source.

4. The system of claim 1 wherein the first GPS receiver is configured to receive GPS-related information comprising at least one of:

a number of GPS satellites received by said first GPS receiver, a set of specific satellites received by said first GPS receiver, a signal-to-noise ratio associated with a GPS satellite signal received by said first GPS receiver, a carrier-to-noise ratio associated with a GPS satellite signal received by said first GPS receiver, a satellite pseudorange determined by said first GPS receiver, a rate of change of a satellite pseudorange, a rate of change of a signal-to-noise ratio associated with a GPS satellite signal received by said first GPS receiver, a rate of change of a carrier-to-noise ratio associated with a GPS satellite signal received by said first GPS receiver, a power associated with a GPS satellite signal received by said first GPS receiver, and an in-band power density of a signal received from a GPS satellite by said first GPS receiver.

5. The system of claim 1, wherein said first sensor is configured to determine at least one of:

a power level of said signal, a time of arrival of said signal, a line of bearing of said signal, and a signal power as a function of angle.

6. The system, of claim 1 wherein said first GPS receiver is remote from said user interface.

7. The system of claim 1 wherein said second processing system at least partially computes the probable location data using at least one of:

a power difference on arrival calculation, a time difference of arrival calculation, an angle of arrival calculation, and a terrain/elevation masking calculation.

8. A method for detecting errors in GPS accuracy, comprising:

receiving first GPS-related data at a first marker device;

calculating, from the first GPS-related data, a first GPS parameter for the first marker;

receiving second GPS-related data at a second marker device different from the first marker device;

calculating, from the second GPS-related data, a second GPS parameter for the second marker;

comparing the first GPS parameter and the second GPS parameter; and

issuing a warning if the comparison indicates an irregularity between the first GPS parameter and the second GPS parameter.

9. The method of claim 8, wherein said comparing occurs at a central monitoring unit.

10. The method of claim 8, further comprising:

identifying, in response to said issuing, a potential source of local interference; and

neutralizing the source of local interference.

11. The method of claim 8, wherein the first GPS parameter and the second GPS parameter comprise at least one of:

a quantity of GPS satellites received by the respective marker, a set of specific satellites received by the respective marker, a signal-to-noise ratio associated with a GPS satellite signal received by the respective marker, a carrier-to-noise ratio associated with a GPS satellite signal received by the respective marker, a satellite pseudorange determined by the respective marker, a rate of change of a satellite pseudorange, a rate of change of a signal-to-noise ratio associated with a GPS satellite signal received by the respective marker, a rate of change of a carrier-to-noise ratio associated with a GPS satellite signal received by the respective marker, a power associated with a GPS satellite signal received by the respective marker, and an in-band power density of a signal received from a GPS satellite by the respective marker.

12. A system for locating a source of interference in GPS signals, the system comprising:

a plurality of GPS devices each configured to receive GPS-related data; and

a monitoring unit configured to detect at least one irregularity in a GPS parameter derived from at least a first portion of the GPS-related data, said monitoring unit comprising;

a user interface configured to issue a warning in response to said monitoring unit detecting an irregularity; and

a processor configured to calculate an approximate location of a potential source of interference based on at least a second portion of the GPS-related data.

13. The system of claim 12 wherein said GPS parameter for each GPS device of said plurality of GPS devices comprises at least one of:

a number of GPS satellites received by said GPS device, a set of specific satellites received by said GPS device, a signal-to-noise ratio associated with a GPS satellite signal received by said GPS device, a carrier-to-noise ratio associated with a GPS satellite signal received by said GPS device, a satellite pseudorange determined by said GPS device, a rate of change of a satellite pseudorange determined by said GPS device, a rate of change of a signal-to-noise ratio associated with a GPS satellite signal received by said GPS device, a rate of change of a carrier-to-noise ratio associated with a GPS satellite signal received by said GPS device, a power associated with a GPS satellite signal received by said GPS device, and an in-band power density of a signal received from a GPS satellite by said GPS device.

14. The system of claim 12 wherein the irregularity comprises at least one of:

a discontinuity over time in GPS-related data received by a single GPS device, a predetermined difference between expected and measured GPS-related data received by a single GPS device, and a predetermined divergence among GPS-related data received from the plurality of GPS devices.

15. The system of claim 12 wherein said processor is configured to calculate the approximate location using at least one of:

a power difference on arrival calculation, a time difference of arrival calculation, an angle of arrival calculation, and a terrain/elevation masking calculation.

16. The system of claim 12 wherein at least each of the first and second portion of the GPS-related data represents at least one of:

a power level of the interference, a time-synchronization of the interference, a line of bearing of the interference, and a power level of the interference as a function of angle.

17. A method for detecting errors in GPS accuracy, the method comprising:

detecting, at a plurality of locations, GPS-related data;

calculating at each respective location GPS-related information from the GPS-related data; and

sending the GPS-related information to a central monitoring unit from each location;

wherein the central monitoring unit determines the existence of a signal causing an error in GPS accuracy.

18. The method of claim 17, further comprising identifying, at the central monitoring unit, a probable location of a source of the signal.

19. The method of claim 17, further comprising receiving at least one of configuration and control instructions from the central monitoring unit.

20. The method of claim 17 wherein the GPS-related data comprises at least one of:

a number of GPS satellites received by a GPS device, a set of specific satellites received by a GPS device, a signal-to-noise ratio associated with a GPS satellite signal received by a GPS device, a carrier-to-noise ratio associated with a GPS satellite signal received by a GPS device, a satellite pseudorange determined by a GPS device, a rate of change of a satellite pseudorange, a rate of change of a signal-to-noise ratio associated with a GPS satellite signal received by a GPS device, a rate of change of a carrier-to-noise ratio associated with a GPS satellite signal received by a GPS device, a power associated with a GPS satellite signal received by a GPS device, and an in-band power density of a signal received from a GPS satellite by a GPS device.

21. The method of claim 17, further comprising the central monitoring unit detecting at least one of:

a discontinuity over time in GPS-related data received from a single GPS device, a predetermined difference between expected and measured GPS-related data received from a single GPS device, and a predetermined divergence among GPS-related data received from a plurality of GPS devices.

22. A method for detecting errors in GPS accuracy, comprising:

receiving GPS-related data at a marker;

calculating, from the GPS-related data, at least one derived GPS parameter for the marker;

comparing the at least one derived GPS parameter with a corresponding at least one expected GPS parameter; and

issuing a warning if the comparison indicates an irregularity between any of the derived GPS parameters and any of the corresponding expected GPS parameters;

wherein the expected GPS parameter and the derived GPS parameter comprise at least a quantity of GPS satellites received by the marker.

23. A method for detecting errors in GPS accuracy, comprising:

receiving GPS-related data at a marker;

calculating, from the GPS-related data, at least one derived GPS parameter for the marker;

comparing the at least one derived GPS parameter with a corresponding at least one expected GPS parameter; and

issuing a warning if the comparison indicates an irregularity between any of the derived GPS parameters and any of the corresponding expected GPS parameters;

wherein the expected GPS parameter and the derived GPS parameter comprise at least a set of specific satellites received by the marker.