Squaring Loss Inhibition for Low Signal Levels in Positioning Systems

• US 20100279732A1
• Filed: 05/04/2009
• Published: 11/04/2010
• Est. Priority Date: 05/04/2009
• Status: Active Grant

• Current Assignee: Andreas Schmid, Joakim Landmark, Mikael Hjelm
• Original Assignee: Andreas Schmid, Joakim Landmark, Mikael Hjelm
• Inventors: Schmid, Andreas, Hjelm, Mikael, Landmark, Joakim
• Granted Patent: US 8,547,950 B2
• Time in Patent Office: Days
• US Class Current: 455/552.1
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/246 involving long acquisition integration times, extended snapshots of signals or methods specifically directed towards weak signal acquisition
• CPC Class Codes: G01S 19/25 involving aiding data received from a cooperating element, e.g. assisted GPS
• CPC Class Codes: G01S 19/27 creating, predicting or correcting ephemeris or almanac data within the receiver
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

Embodiments related to acquisition, detection, and processing of a high-frequency signal in a global positioning system are described and depicted.

Claims

1. A receiver, comprising:

a data source configured to produce a replica of a data bit sequence modulated on a CDMA (“

code division multiple access”

) signal;

a coherent integration stage configured to coherently integrate the CDMA signal over a first period of integration employing the replica of the data bit sequence.

2. The receiver as claimed in claim 1, wherein the data source is configured to produce the replica of the data bits employing a signal received from an external wireless source modulated with the data bits.

3. The receiver as claimed in claim 2, wherein the signal received from the external wireless source is received on a frequency different from a carrier frequency of the CDMA signal.

4. The receiver as claimed in claim 1, wherein the replica of the data bit sequence modulated on the CDMA signal is produced in the receiver employing assist data received from an external wireless source.

5. The receiver as claimed in claim 4, wherein the assist data comprises a satellite almanac and a timing reference.

6. The receiver as claimed in claim 1, further comprising:

a downconversion stage configured to convert the CDMA signal to a baseband signal; and

a frequency estimation stage configured to produce a frequency correction signal for a local oscillator to produce a frequency-corrected local oscillator signal, wherein the coherent integration stage is configured to coherently integrate the CDMA signal over a second period of integration employing the replica of the data bit sequence modulated on the CDMA signal and the frequency-corrected local oscillator signal.

7. The receiver as claimed in claim 6, wherein the coherent integration stage is configured to coherently re-integrate the CDMA signal over the first period of integration employing the replica of the data bits and the frequency-corrected local oscillator signal.

8. The receiver as claimed in claim 1, wherein the receiver is a global navigation satellite system receiver.

9. A receiver, comprising:

a modulation data overlay source configured to produce real-time modulation data for a CDMA signal in a selected GNSS (“

global navigation satellite system”

) subframe of the CDMA signal, the real-time modulation data produced employing previously stored satellite data or assist data, the producing the real-time modulation data initiated upon receipt of a timing signal from an external wireless source;

a coherent integration stage configured to coherently integrate the CDMA signal over a first period of integration employing the real-time modulation data.

10. The receiver as claimed in claim 9, wherein the previously stored satellite data or assist data comprises almanac data.

11. The receiver as claimed in claim 9, wherein the previously stored satellite data or assist data comprises previously stored satellite modulation data from a previously transmitted Galileo or GPS (“

Global Positioning System”

) subframe.

12. The receiver as claimed in claim 11, wherein the previously stored satellite modulation data comprises data received from the external wireless source with an external wireless source carrier frequency different from a carrier frequency of the CDMA signal.

13. The receiver as claimed in claim 9, wherein the selected GPS subframe comprises at least one of GPS subframe 4 and GPS subframe 5.

14. A method comprising:

producing a replica of data bits modulated on a CDMA signal;

coherently integrating the CDMA signal over a first period of integration employing the replica of the data bits.

15. The method as claimed in claim 14, wherein the replica of the data bits is produced employing a signal received from an external wireless source modulated with the data bits.

16. The method as claimed in claim 15, wherein the signal received from the external wireless source is received on a frequency different from a carrier frequency of the CDMA signal.

17. The method as claimed in claim 14, wherein the replica of the data bits is produced employing assist data received from an external wireless source.

18. The method as claimed in claim 17, wherein the assist data comprises a satellite almanac and a timing reference.

19. The method as claimed in claim 14, further comprising:

converting the CDMA signal to a baseband signal;

producing a frequency correction signal for a local oscillator; and

coherently integrating the CDMA signal over a second period of integration employing the replica of the data bits and a local oscillator signal with a frequency corrected by the frequency correction signal.

20. The method as claimed in claim 14, wherein the CDMA signal is a global navigation satellite system signal.

21. A method of receiving a CDMA signal, comprising:

producing real-time modulation data in a selected subframe of the CDMA signal from previously stored satellite data or assist data upon receipt of a timing signal from an external wireless source; and

coherently integrating the CDMA signal over a first period of integration employing the real-time modulation data.

22. The method as claimed in claim 21, wherein the previously stored satellite data or assist data comprises almanac data.

23. The method as claimed in claim 21, wherein the previously stored satellite data or assist data comprises previously stored satellite modulation data from a previously transmitted subframe.

24. The method as claimed in claim 23, wherein the previously stored satellite modulation data comprises data received from the external wireless source with an external wireless source carrier frequency different from a carrier frequency of the CDMA signal.

25. The method as claimed in claim 21, wherein the selected subframe comprises at least one of a GPS (“

global positioning system”

) subframe 4 and GPS subframe 5.