Methods and apparatuses for processing of global positioning system signals with a matched filter

• US 6,724,807 B1
• Filed: 12/04/2000
• Issued: 04/20/2004
• Est. Priority Date: 12/04/2000
• Status: Expired due to Term

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Inventors: Conflitti, Paul, Krasner, Norman F.
• Primary Examiner(s): Ghayour, Mohammad H.
• Assistant Examiner(s): Nguyen, Dung X.
• Application Number:
  US09/729,812
• Publication Number:
  US 20040076223A1
• Time in Patent Office: 1,233 Days
• Field of Search: 375/143, 375/145, 375/149, 375/137, 375/343, 375/142, 375/150, 375/130, 375/148, 375/152, 375/147, 375/267, 375/347, 342/357.06, 342/357.02, 342/157.12, 342/357.05, 342/418, 701/215, 708/314
• US Class Current: 375/143
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 19/254 relating to Doppler shift of satellite signals
• 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 5/0036 of measured values, i.e. measurement on mobile and position calculation on base station

Abstract

Methods and apparatuses for processing Satellite Positioning System (SPS) signals. In one exemplary method, a first set of frequency coefficients, which corresponds to a first Doppler frequency of an SPS signal, is determined, and said SPS signal is processed in a matched filter with the first set of frequency coefficients during a first window of time. A second set of frequency coefficients, which corresponds to a second Doppler frequency of the SPS signal, is determined, and the SPS signal is processed in the matched filter with the second set of frequency coefficients during a second window of time, where the first and second windows of time occur within a period of time which is not greater than one SPS frame period. In another exemplary method, a first SPS signal is processed in a matched filter with a first set of pseudonoise (PN) coefficients during a first window of time, where the first set of PN coefficients corresponds to the first SPS signal, and a second SPS signal is processed in the matched filter with a second set of PN coefficients (which correspond with the second SPS signal) during a second window of time, wherein the first window and the second windows occur within a period of time not greater than one SPS frame period.

Claims

1. A method for processing substantially concurrently at least two Doppler frequencies of a Satellite Positioning System (SPS) signal, said method comprising:

determining a first set of frequency coefficients corresponding to a first Doppler frequency of said SPS signal;

processing said SPS signal in a matched filter with said first set of frequency coefficients during a first window of time;

determining a second set of frequency coefficients corresponding to a second Doppler frequency of said SPS signal;

processing said SPS signal in said matched filter with said second set of frequency coefficients during a second window of time;

wherein said first and said second windows of time occur within a period of time not greater than one SPS frame period.

2. A method as in claim 1 wherein said first window of time and said second window of time are different and non-overlapping and occur consecutively in time within said period of time.

3. The method of claim 1 further comprising:

generating a series of pseudonoise (PN) coefficients corresponding to said SPS signal;

processing said SPS signal in said matched filter with a first set of PN coefficients during said first window, wherein said first set of PN coefficients is generated by circularly shifting said series of PN coefficients by a first count; and

processing said SPS signal in said matched filter with a second set of PN coefficients during said second window, wherein said second set of PN coefficients is generated by circularly shifting said series of PN coefficients by a second count.

4. A method as in claim 1 further comprising:

storing said first set of frequency coefficients in a first register;

storing said second set of frequency coefficients in said first register.

5. A method as in claim 4 wherein said first register is coupled to a first input of said matched filter and wherein said storing of said first set of frequency coefficients occurs before said processing of said SPS signal with said first set of frequency coefficients and wherein said storing of said second set of frequency coefficients occurs before said processing of said SPS signal with said second set of frequency coefficients.

6. A method as in claim 3 further comprising:

storing said first set of PN coefficients in a second register;

storing said second set of PN coefficients in said second register.

7. A method as in claim 6 wherein said second register is coupled to a second input of said matched filter and wherein said storing of said first set of PN coefficients occurs before said processing of said SPS signal with said first set of PN coefficients and wherein said storing of said second set of PN coefficients occurs before said processing of said SPS signal with said second set of PN coefficients.

8. A method as in claim 4 further comprising:

storing a first set of PN coefficients in a second register;

storing a second set of PN coefficients in said second register.

9. A method as in claim 8 wherein said second register is coupled to a second input of said matched filter and wherein said storing of said first set of PN coefficients occurs before processing of said SPS signal with said first set of PN coefficients and wherein said storing of said second set of PN coefficients occurs before processing of said SPS signal with said second set of PN coefficients.

10. A method for processing substantially concurrently at least two different Satellite Positioning System (SPS) signals, said method comprising:

determining a first set of pseudonoise (PN) coefficients corresponding to a first SPS signal;

processing said first SPS signal in a matched filter with a first set of PN coefficients during a first window of time;

determining a second set of PN coefficients corresponding to a second SPS signal; and

processing said second SPS signal in said matched filter with said second set of PN coefficients during a second window of time;

wherein said first and said second windows of time occur within a period of time not greater than one SPS frame period.

11. The method of claim 10 further comprising:

processing said first SPS signal in said matched filter with a first set of frequency coefficients during said first window; and

processing said second SPS signal in said matched filter with a second set of frequency coefficients during said second window.

12. The method of claim 10 further comprising storing said first set of PN coefficients to a first register and storing said second set of PN coefficients to said first register.

13. The method of claim 12 further comprising storing said first set of frequency coefficients to a second register and storing said second set of frequency coefficients to said second register.

14. A method as in claim 13 wherein said first register is coupled to a first input of said matched filter and said second register is coupled to a second input of said matched filter.

15. A method as in claim 14 wherein said storing of said first set of PN coefficients and said storing of said first set of frequency coefficients occurs before said processing of said first SPS signal in said matched filter and wherein said storing of said second set of PN coefficients and said storing of said second set of frequency coefficients occurs before said processing of said second SPS signal in said matched filter.

16. A method as in claim 10 wherein said first window of time and said second window of time are different and non-overlapping and occur consecutively in time within said period of time.

17. A method as in claim 10 wherein said first set of PN coefficients is generated from a series of PN coefficients by circularly shifting said series of PN coefficients by a first count and wherein said second set of PN coefficients is generated by circularly shifting said series of PN coefficients by a second count.

18. A method as in claim 10 further comprising:

determining a search range, for acquiring at least one of said first SPS signal and said second SPS signal, from a satellite assistance data.

19. A method as in claim 11 wherein said satellite assistance data comprises at least one of (a) Doppler information relative to an SPS satellite;

(b) satellite ephemeris data for an SPS satellite;

(c) approximate location of a mobile SPS receiver which includes said matched filter;

(d) time-of-day information or (e) time of occurrence of the pseudonoise framing epoch of a signal from an SPS satellite.

20. A circuit for substantially concurrently processing at least two Doppler frequencies of a Satellite Positioning System (SPS) signal, said circuit comprising:

an input circuit for receiving said SPS signal;

a data shift register coupled to said input circuit, said data shift register storing said SPS signal;

a matched filter circuit coupled to said data shift register, said matched filter circuit computing an output based on said SPS signal;

a pseudonoise (PN) weight generation circuit having an output, said PN weight generation circuit determining a set of PN coefficients corresponding to said SPS signal;

a PN data shift register having an input which is coupled to said output of said PN weight generation circuit and having an output which is coupled to a first input of said matched filter circuit;

a frequency coefficient generation circuit having an output, said frequency coefficient generation circuit determining a first set of frequency coefficients during a first interval of time and a second set of frequency coefficients during a second interval of time, wherein said first interval of time and said second interval of time occur within a time period no greater than one SPS frame period;

a frequency data shift register having an input which is coupled to said output of said frequency coefficient generation circuit and having an output which is coupled to a second input of said matched filter circuit;

a storage circuit coupled to an output of said matched filter circuit, said storage circuit to store in a first set of memory locations a first output of said matched filter circuit corresponding to said first set of frequency coefficients during a third interval of time, and said storage circuit to store in a second set of memory locations a second output of said matched filter circuit corresponding to said second set of frequency coefficients during a fourth interval of time, wherein said third interval of time and said fourth interval of time occur within a time period no greater than one SPS frame period.

21. A circuit as in claim 20 wherein said first interval of time and said second interval of time are different and non-overlapping and occur consecutively in time within said time period.

22. A circuit as in claim 21 wherein said one SPS frame period is defined by a repetition period of PN data in said SPS signal.

23. A circuit as in claim 20 further comprising:

a control circuit coupled to said frequency coefficient generation circuit, said control circuit controlling when said frequency coefficient generation circuit generates said first set of frequency coefficients and said second set of frequency coefficients.

24. A circuit as in claim 20 further comprising:

a first register having an input coupled to said output of said frequency data shift register and having an output coupled to said second input of said matched filter circuit.

25. A circuit as in claim 20 further comprising:

a second register having an input coupled to said output of said PN data shift register and having an output coupled to said first input of said matched filter circuit, wherein said matched filter circuit is coupled to said PN data shift register through said second register.

26. A circuit as in claim 20 wherein said PN weight generation circuit determines a series of PN coefficients corresponding to said SPS signal and wherein said matched filter circuit processes said SPS signal with a first set of PN coefficients during said first interval of time, said first set of PN coefficients being generated by first circularly shifting said series of PN coefficients by a first count and wherein said matched filter circuit processes said SPS signal with a second set of PN coefficients during said second interval of time, said second set of PN coefficients being generated by second circularly shifting said series of PN coefficients by a second count.

27. A circuit as in claim 26 wherein said first circularly shifting and said second circularly shifting are performed by said PN data shift register.

28. A circuit for substantially concurrently processing at least two Satellite Positioning System (SPS) signals each having a distinct PN spreading code, said circuit comprising:

an input circuit for receiving said SPS signal;

a data shift register coupled to said input circuit, said data shift register storing said SPS signal;

a matched filter circuit coupled to said data shift register to receive said SPS signal and to process said SPS signal;

a pseudonoise (PN) weight generation circuit having an output, said PN weight generation circuit determining a first set of PN coefficients corresponding to a first SPS signal during a first interval of time and determining a second set of PN coefficients corresponding to a second SPS signal during a second interval of time;

wherein said first interval of time and said second interval of time occur within a time period no greater than one SPS frame period;

a PN data shift register having an input which is coupled to said output of said PN weight generation circuit and having an output which is coupled to a first input of said matched filter circuit;

a storage circuit coupled to an output of said matched filter circuit, said storage circuit to store in a first set of memory locations a first output of said matched filter circuit corresponding to said first set of PN coefficients during a third interval of time, and to store in a second set of memory locations a second output of said matched filter corresponding to said second set of PN coefficients during a fourth interval of time, wherein said third interval of time and said fourth interval of time occur within a time period no greater than one SPS frame period.

29. A circuit as in claim 28 further comprising:

a frequency coefficient generation circuit having an output, said frequency coefficient generation circuit determining a first set of frequency coefficients during said first interval of time and a second set of frequency coefficients during said second interval of time;

a frequency data shift register having an input which is coupled to said output of said frequency coefficient generation circuit and having an output which is coupled to a second input of said matched filter circuit.

30. The circuit of claim 28 further comprising a first register coupled to the output of said PN data shift register and coupled to the first input of said matched filter circuit.

31. The circuit of claim 29 further comprising a second register coupled to the output of said frequency data shift register and coupled to the second input of said matched filter circuit.

32. A circuit as in claim 28 wherein said first interval of time and said second interval of time are different and non-overlapping and occur consecutively in time within said time period.

33. A circuit as in claim 32 wherein said one SPS frame period is defined by a repetition period of PN data in said SPS signal.

34. A circuit as in claim 28 further comprising:

a control circuit coupled to said frequency coefficient generation circuit, said control circuit controlling when said frequency coefficient generation circuit generates said first set of frequency coefficients and said second set of frequency coefficients.