Signal verification

• US 8,633,852 B2
• Filed: 09/20/2011
• Issued: 01/21/2014
• Est. Priority Date: 09/20/2010
• Status: Expired due to Fees

• Current Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Original Assignee: STMicroelectronics Limited (STMicroelectronics NV)
• Inventors: Bagnall, Peter
• Primary Examiner(s): Tarcza, Thomas
• Assistant Examiner(s): GOLDMAN, RICHARD A
• Application Number:
  US13/237,611
• Publication Number:
  US 20120072112A1
• Time in Patent Office: 854 Days
• Field of Search: None
• US Class Current: 342/357.23
• CPC Class Codes: G01C 21/24 specially adapted for cosmonautical navigation
• CPC Class Codes: G01S 19/20 Integrity monitoring, fault detection or fault isolation of space segment
• CPC Class Codes: G01S 19/215 issues related to spoofing
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver

Abstract

A first position of a satellite is calculated at a first time in dependence on received orbit data corresponding to an orbit path of the satellite. Anan orbit path of the satellite is modeled from the first position at the first time to a second time to determine a second position of the satellite at the second time. A third position of the satellite is then calculated at the second time in dependence on the received orbit data. The second position and third position are compared to determine a validity of the orbit data.

Claims

1. A method performed by a processor device within a global navigation satellite system receiver, comprising:

calculating a satellite first position at a first time in dependence on received orbit data corresponding to a global navigation satellite orbit path;

modeling a global navigation satellite orbit path from the satellite first position at the first time to a second time to determine a modeled second position of the satellite at the second time;

calculating a satellite second position at the second time in dependence on the received orbit data;

comparing said modeled second position and said satellite second position; and

identifying whether the received orbit data is valid orbit data based on the result of said comparing.

2. The method of claim 1 wherein said orbit data comprises orbit parameters for predicting an orbit path of a global navigation satellite for a segment of flight.

3. The method of claim 1 wherein said modeling is based on an orbit propagation model.

4. The method of claim 3 wherein said orbit propagation model takes into account the effects of at least one of:

at least one gravitational body and solar pressure on the orbit path.

5. The method of claim 1 wherein said orbit data is received at a third time which falls within a period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path.

6. The method of claim 5 wherein said first time is a time before said third time at which the orbit data is received and said second time is a time after said third time.

7. The method of claim 5 wherein said first time is the start of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and the second time is the end time of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and wherein said satellite first position is a position at the start of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and said modeled second position and satellite second position are projected positions at the end of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path.

8. The method of claim 5 wherein the satellite first and second positions are calculated using position and velocity equations with orbit parameters from the orbit data as input parameters.

9. The method of claim 1 wherein comparing said modeled second position and satellite second position comprises:

determining an error corresponding to a difference between the modeled second position and the satellite second position.

10. The method of claim 9 further comprising identifying said orbit data as being invalid if the determined error exceeds a threshold.

11. The method of claim 10 further comprising generating a signal comprising information indicative of whether the orbit data is invalid.

12. A computer readable medium including computer instructions for:

calculating a satellite first position at a first time in dependence on received orbit data corresponding to a global navigation satellite orbit path;

modeling a global navigation satellite orbit path from the satellite first position at the first time to a second time to determine a modeled second position of the satellite at the second time;

calculating a satellite second position at the second time in dependence on the received orbit data;

comparing said modeled second position and said satellite second position; and

identifying whether the received orbit data is valid orbit data based on the result of said comparing.

13. An apparatus comprising:

a processor configured to;

calculate a satellite first position at a first time in dependence on received orbit data corresponding to a global navigation satellite an orbit path;

model a global navigation satellite orbit path from the satellite first position at the first time to a second time to determine a modeled second position of the satellite at the second time;

calculate an actual satellite second position at the second time in dependence on the received orbit data;

compare said modeled second position and said satellite second position; and

identify whether the received orbit data is valid orbit data based on the result of said comparing.

14. The apparatus of claim 13 wherein said orbit data comprises orbit parameters for predicting an orbit path of a global navigation the satellite for a segment of flight.

15. The apparatus of claim 13 wherein said modeling is based on an orbit propagation model.

16. The apparatus of claim 15 wherein said orbit propagation model takes into account the effects of at least one of:

at least one gravitational body and solar pressure on the orbit path.

17. The apparatus of claim 13 wherein said orbit data is received at a third time which falls within a period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path.

18. The apparatus of claim 17 wherein said first time is a time before said third time at which the orbit data is received and said second time is a time after said third time.

19. The apparatus of claim 17 wherein said first time is the start of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and the second time is the end time of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and wherein said satellite first position is a position at the start of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path and said modeled second position and satellite second position are projected positions at the end of the period for which the orbit data describes a segment of the global navigation satellite'"'"'s orbit path.

20. The apparatus of claim 17 wherein the satellite first and second positions are calculated using position and velocity equations with orbit parameters from the orbit data as input parameters.

21. The apparatus of claim 13 configured to compare said modeled second position and satellite second position by determining an error corresponding to a difference between the modeled second position and the satellite second position.

22. The apparatus of claim 21 further configured to identify said orbit data as being invalid if the determined error exceeds a threshold.

23. The apparatus of claim 22 further configured to generate a signal comprising information indicative of whether the orbit data is invalid.

24. An apparatus comprising:

a receiver configured to receive global navigation satellite orbit data; and

a processing device coupled to the receiver and configured to calculate a first position of a global navigation satellite at a first time in dependence on the received global navigation satellite orbit data, model an orbit path of the global navigation satellite from the first position at the first time to a second time to determine a modeled second position of the global navigation satellite at the second time, calculate an actual second position of the global navigation satellite at the second time in dependence on the received global navigation satellite orbit data, compare said modeled second position and said actual second position and determine from the comparison whether said global navigation satellite orbit data is valid.