Method and apparatus for processing satellite positioning system signals

• US 20050080561A1
• Filed: 05/04/2004
• Published: 04/14/2005
• Est. Priority Date: 04/23/1999
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Abraham, Charles, Fuchs, Donald L.
• Granted Patent: US 9,020,756 B2
• Time in Patent Office: Days
• US Class Current: 701/213
• CPC Class Codes: G01S 19/05 providing aiding data
• CPC Class Codes: G01S 19/235 Calibration of receiver components
• CPC Class Codes: G01S 19/252 Employing an initial estimate of location in generating assistance data
• CPC Class Codes: G01S 19/256 relating to timing, e.g. time of week, code phase, timing offset
• CPC Class Codes: G01S 19/258 relating to the satellite constellation, e.g. almanac, ephemeris data, lists of satellites in view
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: G01S 2205/002 for traffic control, mobile tracking, guidance, surveillance or anti-collision
• CPC Class Codes: G01S 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station
• CPC Class Codes: G06F 17/15 Correlation function computation including computation of convolution operations arithmetic circuits for sum of products per se, e.g. multiply-accumulators G06F7/5443; digital filters, e.g. FIR, IIR, adaptive filters H03H17/00
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 1/70754 Setting of search window, i.e. range of code offsets to be searched H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/70757 with increased resolution, i.e. higher than half a chip H04B1/70758 takes precedence
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

Method and apparatus for processing a satellite positioning system (SPS) signal is described. In one example, a timing reference related to a SPS time of day is obtained from a wireless communication signal received by a mobile receiver. A bias in a local clock of the mobile receiver with respect to a frame timing of a repeating code broadcast by the satellite is compensated for in response to the timing reference. An expected code delay window is obtained for the SPS signal at the mobile receiver. The SPS signal is correlated with a reference code within the expected code delay window. In another example, an expected code delay window is obtained at the mobile receiver. The mobile receiver selects a sampling resolution in response to a size of the expected code delay window. The SPS signal is sampled at the selected sampling resolution and then correlated with a reference code.

Claims

1. A method of processing a satellite positioning system signal received by a mobile receiver from a satellite, comprising:

obtaining a timing reference related to a satellite positioning system time of day from a wireless communication signal received at said mobile receiver;

compensating for a bias in a local clock of said mobile receiver with respect to a frame timing of a repeating code broadcast by said satellite in response to said timing reference;

obtaining an expected code delay window for said satellite positioning system signal at said mobile receiver; and

correlating said satellite positioning system signal with a reference code within said expected code delay window.

2. The method of claim 1, wherein said step of obtaining said expected code delay window comprises:

receiving acquisition assistance data from a server in communication with the mobile receiver; and

deriving said expected code delay window in response to said acquisition assistance data.

3. The method of claim 1, wherein further comprising:

determining a delay between said mobile receiver and a base station in communication with said mobile receiver;

adjusting said timing reference in response to said delay.

4. The method of claim 2, wherein said assistance data comprises expected pseudorange data and said expected code delay window is generated using said expected pseudorange data.

5. The method of claim 1, wherein said step of obtaining said expected code delay window comprises:

obtaining satellite trajectory data at said mobile receiver;

obtaining an estimated location of said mobile receiver; and

computing said code delay window in response to said satellite trajectory data and said estimated location.

6. The method of claim 5, wherein said satellite trajectory data comprises ephemeris.

7. The method of claim 5, wherein said satellite trajectory data comprises almanac data.

8. The method of claim 5, wherein said satellite trajectory data is received from a server in communication with said mobile receiver.

9. The method of claim 1, wherein said expected code delay window spans only a portion of said repeating code.

10. The method of claim 1, further comprising:

selecting a sampling resolution in response to said expected code delay window; and

sampling said satellite positioning system signal at said selected sampling resolution prior to correlation step.

11. The method of claim 1, further comprising:

repeating said steps of obtaining an expected code delay window and correlating for at least one additional satellite positioning system signal received by said mobile receiver from a respective at least one additional satellite.

12. The method of claim 1, further comprising:

computing a pseudorange from said mobile receiver to said satellite in response to results of said correlation.

13. The method of claim 1, wherein said step of compensating comprises:

comparing said timing reference with a timing of said local clock to estimate said bias.

14. The method of claim 1, wherein said step of compensating comprises:

synchronizing a timing of said local clock to said timing reference.

15. A method of processing a satellite positioning system signal received by a mobile receiver from a satellite, comprising:

obtaining an expected code delay window at said mobile receiver;

selecting a sampling resolution in response to a size of said expected code delay window;

sampling said satellite positioning system signal at said selected sampling resolution; and

correlating said sampled satellite positioning system signal with a reference code.

16. The method of claim 15, wherein said step of selecting a sampling resolution comprises:

selecting a first sampling resolution in response to said size failing a threshold; and

selecting a second sampling resolution in response to said size satisfying said threshold.

17. The method of claim 16, wherein said second sampling resolution is higher than said first sampling resolution.

18. The method of claim 15, further comprising:

obtaining a timing reference related to a satellite positioning system time-of-day from a time synchronization signal broadcast by a base station in communication with said mobile receiver; and

compensating for a bias in a local clock of said mobile receiver with respect to a frame timing of a repeating code broadcast by said satellite in response to said timing reference.

19. The method of claim 18, further comprising:

obtaining acquisition assistance data; and

deriving said expected code delay window in response to said acquisition assistance data.

20. The method of claim 19, wherein said sampled satellite positioning system signal is correlated within said expected code delay window.

21. The method of claim 20, wherein said expected code delay window spans only a portion of said repeating code.

22. The method of claim 19, wherein said acquisition assistance data comprises expected pseudorange data and said expected code delay window is generated using said expected pseudorange data.

23. The method of claim 18, further comprising:

obtaining satellite trajectory data;

forming acquisition assistance data within said mobile receiver using said satellite trajectory data; and

deriving said expected code delay window in response to said acquisition, assistance data.

24. The method of claim 23, wherein said sampled satellite positioning system signal is correlated within said expected code delay window.

25. The method of claim 24, wherein said expected code delay window spans only a portion of said repeating code.

26. The method of claim 24, wherein said acquisition assistance data comprises expected pseudorange data and said expected code delay window is generated using said expected pseudorange data.

27. The method of claim 15, further comprising:

repeating said steps of obtaining, selecting, sampling, and correlating for at least one additional satellite positioning system signal received at said mobile receiver from a respective at least one additional satellite.

28. The method of claim 15, further comprising:

computing a pseudorange from said mobile receiver to said satellite in response to results of said correlation.

29. A mobile receiver, comprising:

a wireless transceiver for receiving a wireless communication signal from a wireless network;

a satellite signal receiver for receiving satellite positioning system signal broadcast by a satellite, said satellite signal receiver having correlator circuitry and a local clock; and

a processor for obtaining an expected code delay window for said satellite positioning system signal, obtaining a timing reference related to a satellite positioning system time of day from said wireless communication signal, and providing said timing reference to said satellite signal receiver to compensate for a bias in said local clock with respect to a frame timing of a repeating code broadcast by said satellite in response to said timing reference;

wherein said correlator circuitry is configured to correlate said satellite positioning system signal with a reference code within said expected code delay window using said local clock.

30. A mobile receiver, comprising:

a processor for obtaining an expected code delay window; and

a satellite signal receiver for receiving satellite positioning system signal broadcast by a satellite, said satellite signal receiver configured to select a sampling resolution in response to a size of said expected code delay window, sample said satellite positioning system signal at said selected sampling resolution, and correlate said sampled satellite positioning system signal with a reference code.

31. The mobile receiver of claim 30, further comprising:

a communications device for receiving external aiding data at said mobile receiver;

wherein said processor is configured to obtain said expected code delay window in response to said external aiding data.

32. The mobile receiver of claim 31, wherein said communications device comprises a wireless transceiver configured to receive a wireless communication signal.

33. The mobile receiver of claim 32, wherein said satellite signal receiver comprises a local clock, wherein said external aiding data further comprises a time synchronization signal, and wherein said satellite signal receiver is configured to compensate for a bias in said local clock in response to said time synchronization signal.

34. The mobile receiver of claim 31, wherein said external aiding data further comprises acquisition assistance data.

35. The mobile receiver of claim 31, wherein said external aiding data further comprises satellite trajectory data.