PROCESSING OF SATELLITE NAVIGATION SYSTEM SIGNALS

• US 20100328147A1
• Filed: 06/24/2008
• Published: 12/30/2010
• Est. Priority Date: 06/26/2007
• Status: Active Grant

• Current Assignee: Titan Intelligence Technology Limited
• Original Assignee: NXP B.V. (NXP Semiconductors NV)
• Inventors: Peeters, Johan F.J., Daems, Frank C.H.
• Granted Patent: US 8,471,763 B2
• Time in Patent Office: Days
• US Class Current: 342/357.25
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G07B 15/02 taking into account a variable factor such as distance or time, e.g. for passenger transport, parking systems or car rental systems G07B15/06 takes precedence; taximeters G07B13/00; parking meters per se G07F17/24; car rental systems per se G07B15/00
• CPC Class Codes: G07B 15/06 Arrangements for road pricing or congestion charging of vehicles or vehicle users, e.g. automatic toll systems

Abstract

A system implements a location based service, and comprises a satellite navigation receiver implementing a position tracking function for providing the location of a user of the service. An analogue rf receiver (12) receives satellite signals and performs at least a frequency downconversion. Correlation and decoding functions are applied to the downconverted signals for deriving location information from detected specific satellite signals. The system further comprises a server (30) for receiving samples of the downconverted signals, and for verifying the samples are consistent with the expected satellite signals at that time and location. The invention provides a counter measure for detecting the counterfeiting of, or tampering with, the satellite signals at the receiver. A check can be made that the received satellite signals correspond to those which are expected at that location and time.

Claims

1. A system implementing a location based service, comprising;

a mobile satellite navigation receiver implementing a position tracking function for providing a location of a user of the service,

wherein the mobile receiver comprises;

an analogue rf receiver for receiving satellite signals and performing at least a frequency downconversion;

signal processing means for performing correlation functions to the downconverted signals for detecting specific satellite signals; and

decoding means for deriving location information from the detected specific satellite signals; and

means, for receiving samples of the downconverted signals from the mobile receiver, and for verifying that the samples are consistent with the expected satellite signals at that time and location.

2. A system as claimed in claim 1, wherein the expected satellite signals are derived from the determined location, time and the satellite positions at that time.

3. A system as claimed in claim 1, wherein the expected satellite signals are derived from an analysis of the downconverted signals from a plurality of users at the same time and in close proximity to each other.

4. A system as claimed in claim 3, further comprising a timing generator for defining a time at which the samples of downconverted signals for multiple users are provided to the server.

5. A system as claimed in claim 4, wherein the timing generator generates a random timestamp.

6. A system as claimed in claim 1, wherein the system is a road toll system, and the system further comprises means for determining a road toll from the derived location information.

7. A method of determining a location of a user of a system which implements a location based service, the method comprising:

the user receiving satellite signals and performing at least a frequency downconversion in a mobile receiver;

the user providing the downconverted signals to signal processing means within the mobile receiver for performing correlation functions to the downconverted signals for detecting specific satellite signals and to decoding means for deriving location information from the detected specific satellite signals,

the user providing samples of the downconverted signals from the mobile receiver to the service provider, and

service provider verifying the samples are consistent with the expected satellite signals at that time and location.

8. A method as claimed in claim 7, wherein the expected satellite signals are derived from the determined location, time and the satellite positions at that time.

9. A method as claimed in claim 7, wherein the expected satellite signals are derived from an analysis of the downconverted signals from a plurality of users at the same time and in close proximity to each other.

10. A method as claimed in claim 9, further comprising defining a time at which the samples of downconverted signals for multiple users are provided to the server.

11. A method as claimed in claim 10, wherein defining a time comprises generating a random timestamp.

12. A method as claimed in claim 7, further comprising determining a road toll from the derived location information.

14. A system as claimed in claim 12, wherein the expected satellite signals are derived from the determined location, time and the satellite positions at that time.

15. A system as claimed in claim 12, wherein the expected satellite signals are derived from an analysis of the downconverted signals from a plurality of users at the same time and in close proximity to each other.

16. A system as claimed in claim 15, further comprising a timing generator for defining a time at which the samples of downconverted signals for multiple users are provided to the server.

17. A system as claimed in claim 16, wherein the timing generator generates a random timestamp.

18. A system as claimed in claim 12, wherein the system is a road toll system, and the system further comprises a calculator that determines a road toll from the derived location information.

13. A system implementing a location based service, comprising:

a mobile satellite navigation receiver implementing a position tracking function for providing a location of a user of the service,

wherein the mobile receiver comprises;

an analogue rf receiver for receiving satellite signals and performing at least a frequency downconversion;

a signal processor that performs correlation functions to the downconverted signals for detecting specific satellite signals; and

a decoder that derives location information from the detected specific satellite signals; and

a receiver that obtains samples of the downconverted signals from the mobile receiver, and verifies that the samples are consistent with the expected satellite signals at that time and location.

19. A method of determining a location of a user of a system which implements a location based service, the method comprising:

the user receiving satellite signals and performing at least a frequency downconversion in a mobile receiver;

the user providing the downconverted signals to a signal processor within the mobile receiver for performing correlation functions to the downconverted signals for detecting specific satellite signals and to a decoder that derives location information from the detected specific satellite signals,

the user providing samples of the downconverted signals from the mobile receiver to the service provider, and

the service provider verifying the samples are consistent with the expected satellite signals at that time and location.

20. A method as claimed in claim 19, wherein the expected satellite signals are derived from the determined location, time and the satellite positions at that time.

21. A method as claimed in claim 19, wherein the expected satellite signals are derived from an analysis of the downconverted signals from a plurality of users at the same time and in close proximity to each other.

22. A method as claimed in claim 21, further comprising defining a time at which the samples of downconverted signals for multiple users are provided to the server.

23. A method as claimed in claim 22, wherein defining a time comprises generating a random timestamp.

24. A method as claimed in claim 19, further comprising determining a road toll from the derived location information.