Method and apparatus for performing signal processing using historical correlation data

• US 20060209935A1
• Filed: 12/19/2005
• Published: 09/21/2006
• Est. Priority Date: 05/18/2001
• Status: Active Grant

• Current Assignee: Avago Technologies General IP PTE Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Abraham, Charles, Tapucu, Emre
• Granted Patent: US 7,995,682 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• 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
• 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: H04B 2201/70715 with application-specific features

Abstract

A method and apparatus for estimating a satellite signal parameter in a satellite positioning system receiver is described. In an example, a plurality of correlation results between a satellite signal and a reference signal is generated and stored in a memory. At least one satellite signal parameter is estimated from the plurality of correlation results using a co-processor integrated within the satellite positioning system receiver. As the coprocessor estimates the parameter, new correlation results are added to the memory. The at least one satellite signal parameter is then provided to the processor.

Claims

1. A method of estimating a satellite signal parameter in a satellite positioning system receiver, comprising:

generating a plurality of correlation results between a satellite signal and a reference signal;

storing the plurality of correlation results in a memory;

estimating at least one satellite signal parameter from the plurality of correlation results using a co-processor integrated within the satellite positioning system receiver, while estimating the at least one satellite signal parameter, storing new correlation results in the memory; and

providing the at least one satellite signal parameter to a processor.

2. The method of claim 1, further comprising:

estimating at least one receiver parameter using the at least one satellite signal parameter.

3. The method of claim 1, wherein the memory is a repeated use buffer and the plurality of correlation results forms a stream that is temporarily stored in the repeated use buffer.

4. The method of claim 3, wherein the estimating step further comprises:

accessing a portion of the stored stream; and

repeatedly processing the portion to estimate the at least one satellite signal parameter.

5. The method of claim 4 wherein the at least one satellite signal parameter comprises bit timing and Doppler frequency.

6. The method of claim 1, wherein the estimating step comprises:

computing a plurality of complex dot-products using the stored correlation results;

selecting a bit-timing offset;

summing complex dot-products from the plurality of complex dot-products that correspond to the selected bit timing offset; and

repeating the selecting step and the summing step for a plurality of bit-timing offsets to form a histogram.

7. The method of claim 8, wherein the estimating step further comprises:

frequency correcting the correlation history using a Doppler offset.

8. The method of claim 1 wherein the generating step generates the plurality of correlation results at a first rate and the estimating step processes the plurality of correlation results to estimate the at least one satellite signal parameters at a second rate, where the second rate is faster than the first rate.

9. The method of claim 8 wherein the estimating step repeatedly processes the plurality of correlation results while the plurality of correlation results are generated in real-time.

10. The method of claim 1 wherein the generating step produces correlation results for a plurality of channels and a single co-processor performs the estimating step.

11. The method of claim 1 wherein the plurality of correlation results are generated for a plurality of channels and the co-processor is a single co-processor.

12. An apparatus for estimating a satellite signal parameter in a satellite positioning system receiver, comprising:

a correlator for generating a plurality of correlation results between a satellite signal and a reference signal;

a repeated use buffer for storing the plurality of correlation results;

a co-processor, integrated within the satellite positioning system receiver, for estimating at least one satellite signal parameter from the plurality of correlation results, while estimating the at least one satellite signal parameter, the repeated use buffer stores new correlation results in the memory; and

means for providing the at least one satellite signal parameter to a processor.

13. The apparatus of claim 12, wherein the repeated use buffer comprises a circular buffer.

14. The apparatus of claim 12, wherein the co-processor comprises at least one of:

a complex modulator for frequency correcting the plurality of correlation results;

a complex power unit for computing power in response to the plurality of correlation results;

a complex cross-product unit for computing complex cross-products in response to the plurality of correlation results;

a complex dot-product unit for computing complex dot-products in response to the plurality of correlation results;

a coherent integration unit for coherently integrating the plurality of correlation results;

a non-coherent integration unit for non-coherently integrating the plurality of correlation results;

or

a noise statistics unit for determining noise statistics in response to the plurality of correlation results.

15. The apparatus of claim 12, wherein the plurality of correlation results form a stream of correlation results corresponding to a respective at least one relative time delay between the satellite signal and the reference signal.

16. The apparatus of claim 15 wherein the coprocessor accesses a portion of the stream to estimate the at least one satellite signal parameter.

17. The apparatus of claim 12 wherein the correlator generates the plurality of correlation results at a first rate and the coprocessor processes the plurality of correlation results at a second rate, where the second rate is faster than the first rate.

18. The apparatus of claim 12 wherein the coprocessor repeatedly processes the plurality of correlation results while the plurality of correlation results are generated by the correlator in real-time.

19. The apparatus of claim 12 further comprising a plurality of correlators for generating correlation results for a plurality of channels, and wherein a single co-processor performs the estimating step using the correlation results from the plurality of correlators.