Adaptive coherent integration time

• US 8,094,072 B2
• Filed: 05/05/2008
• Issued: 01/10/2012
• Est. Priority Date: 05/05/2008
• Status: Expired due to Fees

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Pon, Rayman
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US12/115,438
• Publication Number:
  US 20090273514A1
• Time in Patent Office: 1,345 Days
• Field of Search: 342/357.06, 342/357.13, 342/357.15, 342/357.29, 342/357.42, 342/357.48, 342/357.69, 701/213, 701/215
• US Class Current: 342/357.69
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence

Abstract

A mobile receiver having a coherent integration time that can be adaptively lengthened and shortened. The coherent integration time is based on determining whether information is already known regarding a received satellite signal. Thus, when information, such as, ephemeris, satellite clock, time, almanac, and/or other information, is known, the coherent integration time can be set to a longer time and when information is not known, the information can be set at a shorter time frame.

Claims

1. A method for adaptively adjusting a coherent integration time of a mobile receiver, the method comprising:

receiving a current bit of a signal at the mobile receiver;

determining whether any of a next number of bits N in the signal are known;

setting the coherent integration time to a first value based on knowing at least all the next number N of bits, where N corresponds to a maximum coherent integration time based on one or more frequency bin processing parameters;

setting the coherent integration time to a second value based on knowing fewer than N of the next number of bits, the second value shorter than the first value; and

setting the coherent integration time to a third value if none of the next number N of bits are known, the third value shorter than the second value.

2. The method of claim 1 wherein determining whether any of the next number of bits N in the signal are known comprises determining whether information indicative of any of the next number of bits is valid information.

3. The method of claim 1 wherein the next number of bits N in the signal include at least one bit indicative of orbital position information.

4. The method of claim 3 wherein the next number of bits N in the signal include at least one bit indicative of almanac information and/or at least one bit indicative of ephemeris information.

5. The method of claim 1 wherein the next number of bits N in the signal include at least one bit indicative of satellite clock information.

6. The method of claim 1 wherein the next number of bits N in the signal include at least one bit indicative of time and/or synchronization information.

7. The method of claim 1 wherein the next number of bits N in the signal include at least one bit indicative of ionosphere, UTC (Coordinated Universal Time), and/or satellite health information.

8. The method of claim 1 wherein the receiving a current bit of a signal comprises receiving a current bit of a signal from a positioning system selected from the group of positioning systems consisting of:

a satellite positioning system;

a terrestrial positioning system, and a satellite and terrestrial positioning system.

9. The method of claim 8 wherein the satellite positioning system is selected from the group of satellite positioning systems consisting of:

Global Positioning System, Galileo positioning system, Glonass. Compass/Beidou, and Quasi-Zenith Satellite System (QZSS).

10. The method of claim 2 wherein determining whether the information indicative of any of the next number of bits is valid information comprises determining the age of the information indicative of any of the next known number of bits.

11. The method of claim 10 further comprising setting a counter to indicate new information when new almanac information, new ephemeris information, new satellite clock information, and/or new time information is received.

12. The method of claim 10 wherein determining the age of the information indicative of any of the next known number of bits comprises determining the age by comparing a current time with a time of acquisition of the information indicative of the next known number of bits.

40. The method of claim 1, wherein the one or more frequency bin processing parameters comprise a frequency bin number and/or a frequency bin width.

13. A computer program product comprising:

a computer readable storage medium comprising;

program code to access information indicative of a signal at the mobile receiver;

program code to determine an amount of future information contained in the signal that is known;

program code to adaptively set a coherent integration time based on the amount of known future information, wherein the program code is to adaptively set the coherent integration time to a coherent integration time less than or equal to a maximum coherent integration time based on one or more frequency bin processing parameters; and

program code to set the coherent integration time to a default value if there is no known information.

14. The computer program product of claim 13 wherein the program code to determine an amount of future information contained in the signal that is known comprises program code to set a counter/timer to determine the validity of stored information.

15. The computer program product of claim 13 comprising code to store satellite orbital information to memory.

16. The computer program product of claim 15 wherein the satellite orbital information includes at least some ephemeris information and/or at least some almanac information.

17. The computer program product of claim 13 comprising code to store satellite clock information to memory.

18. The computer program product of claim 13 comprising code to store time and synchronization information to memory.

41. The computer program product of claim 13, wherein the one or more frequency bin processing parameters comprise a frequency bin number and/or a frequency bin width.

19. A mobile device comprising:

a receiver to receive navigation signals, the navigation signals including a selected bit;

a processor configured to adaptively adjust a coherent integration time by;

determining whether any of a next number of bits N subsequent to the selected bit in the signal are known;

setting the coherent integration time to a first value based on knowing at least all the next number N of bits, where N corresponds to a maximum coherent integration time based on one or more frequency bin processing parameters;

setting the coherent integration time to a second value based on knowing fewer than N of the next number of bits, the second value shorter than the first value; and

setting the coherent integration time to a third value if none of the next number N of bits are known, the third value shorter than the second value.

20. The mobile device of claim 19, wherein determining whether any of the next number of bits N subsequent to the selected bit in the signal are known comprises determining whether information indicative of any of the next number of bits is valid information.

21. The mobile device of claim 19 wherein the next number of bits N in the signal include at least one bit indicative of orbital position information.

22. The mobile device of claim 21 wherein the next number of bits N in the signal include at least one bit indicative of almanac information and/or at least one bit indicative of ephemeris information.

23. The mobile device of claim 19 wherein the next number of bits N in the signal include at least one bit indicative of satellite clock information.

24. The mobile device of claim 19 wherein the next number of bits N in the signal include at least one bit indicative of time and/or synchronization information.

25. The mobile device of claim 19 wherein the next number of bits N in the signal include at least one bit indicative of ionosphere, UTC (Coordinated Universal Time), and/or satellite health information.

26. The mobile device of claim 19 wherein the receiving a selected bit of a signal comprises receiving a current bit of a signal from a positioning system selected from the group of positioning systems consisting of:

a satellite positioning system;

a terrestrial positioning system, and a satellite and terrestrial positioning system.

27. The mobile device of claim 26 wherein the satellite positioning system is selected from the group of satellite positioning systems consisting of:

Global Positioning System, Galileo positioning system, Glonass, Compass/Beidou, and Quasi-Zenith Satellite System (QZSS).

42. The mobile device of claim 19, wherein the one or more frequency bin processing parameters comprise a frequency bin number and/or a frequency bin width.

28. A mobile device comprising:

means for receiving navigation signals including a selected signal bit;

means for determining whether any of a next number of bits N subsequent to the selected signal bit in the signal are known;

means for adaptively setting a coherent integration time for integrating correlation results, the means for adaptively setting the coherent integration time comprising means for;

setting the coherent integration time to a first value based on knowing at least all the next number N of bits, where N corresponds to a maximum coherent integration time based on one or more frequency bin processing parameters;

setting the coherent integration time to a second value based on knowing fewer than N of the next number of bits, the second value shorter than the first value; and

setting the coherent integration time to a third value if none of the next number N of bits are known, the third value shorter than the second value.

29. The mobile device of claim 28 wherein the means for determining whether any of the next number of bits N in the signal are known comprises means for determining whether information indicative of any of the next number of bits is valid information.

30. The mobile device of claim 28 wherein the next number of bits N in the signal include at least one bit indicative of orbital position information.

31. The mobile device of claim 30 wherein the next number of bits N in the signal include at least one bit indicative of almanac information and/or at least one bit indicative of ephemeris information.

32. The mobile device of claim 28 wherein the next number of bits N in the signal include at least one bit indicative of satellite clock information.

33. The mobile device of claim 28 wherein the next number of bits N in the signal include at least one bit indicative of time and/or synchronization information.

34. The mobile device of claim 28 wherein the next number of bits N in the signal include at least one bit indicative of ionosphere, UTC (Coordinated Universal Time), and/or satellite health information.

35. The mobile device of claim 28 wherein the means for receiving a current bit of a signal comprises means for receiving a current bit of a signal from a positioning system selected from the group of positioning systems consisting of:

a satellite positioning system;

a terrestrial positioning system, and a satellite and terrestrial positioning system.

36. The mobile device of claim 35 wherein the satellite positioning system is selected from the group of satellite positioning systems consisting of:

Global Positioning System, Galileo positioning system, Glonass, Compass/Beidou, and Quasi-Zenith Satellite System (QZSS).

37. The mobile device of claim 29 wherein the means for determining whether the information indicative of any of the next number of bits is valid information comprises means for determining the age of the information indicative of any of the next known number of bits.

38. The mobile device of claim 37 further comprising means for setting a counter to indicate new information when new almanac information, new ephemeris information, new satellite clock information, and/or new time information is received.

39. The mobile device of claim 37 wherein the means for determining the age of the information indicative of any of the next known number of bits comprises means for determining the age by comparing a current time with a time of acquisition of the information indicative of the next known number of bits.

43. The mobile device of claim 28, wherein the one or more frequency bin processing parameters comprise a frequency bin number and/or a frequency bin width.