METHOD AND APPARATUS FOR PROVIDING AN ENERGY-BASED SIGNAL TRACKING LOOP

• US 20080112516A1
• Filed: 01/15/2008
• Published: 05/15/2008
• Est. Priority Date: 05/18/2001
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Global Locate Incorporated (Broadcom, Inc.)
• Inventors: Abraham, Charles, Goldberg, Jason
• Granted Patent: US 8,098,716 B2
• Time in Patent Office: Days
• US Class Current: 375/343
• CPC Class Codes: H04B 1/70752 Partial correlation
• CPC Class Codes: H04B 1/7085 using a code tracking loop, e.g. a delay-locked loop

Abstract

A method and apparatus for tracking a signal comprises correlating a digital signal with a code using a hypothesis at a plurality of frequencies and at least one delay to produce correlation results, measuring an energy value of the correlation results, adjusting at least one of the frequency or delay in response to the measured energy value to form the hypothesis.

Claims

5-1. The method of claim 5 wherein the dynamic model is an extended Kalman filter.

12. A method of tracking a signal comprising:

(a) correlating a digital signal with a code using a hypothesis at a plurality of frequencies and at least one delay to produce correlation results;

(b) producing a measured energy vector using the correlation results, where the measured energy vector comprises a frequency quantity and a delay quantity; and

(c) updating a frequency, and delay states of an extended Kalman filter in response to the measured energy vector to form the hypothesis.

13. The method of claim 12 further comprising:

(d) repeating steps (a), (b), (c) and (d) to improve the magnitude of the measured energy vector.

14. The method of claim 12 further comprising:

tracking, over time, the measured energy vector of the correlation results; and

improving the magnitude of the energy vector using adjustments of at least one of the frequency or delay.

15. The method of claim 12 wherein the correlating step is performed using a plurality of correlators measuring a correlation result having delay as a variable, a plurality of correlators measuring a correlation result having frequency as a variable, and a punctual correlator.

16. The method of claim 15 wherein the correlators define a multi-dimensional correlation space representing an energy amount within the correlation result.

17. The method of claim 15 wherein the plurality of correlators measuring a correlation result having delay as a variable comprise an early correlator having a delay that is earlier than a delay of the punctual correlator and a late correlator having a delay that is later than a delay of the punctual correlator, and wherein the plurality of correlators measuring a correlation result having frequency as a variable comprise a high correlator having a frequency that is higher than a frequency of the punctual correlator and a low correlator having a frequency that is lower than a frequency of the punctual correlator.

18. Apparatus for tracking a signal comprising:

(a) a plurality of correlators for correlating a digital signal with a code using a hypothesis at a plurality of frequencies and at least one delay to produce correlation results;

(b) a discriminator for measuring an energy value of the correlation results;

(c) a feedback filter for adjusting at least one of the frequency or delay in response to the measured energy value to form the hypothesis.

19. The apparatus of claim 18 wherein the feedback filter tracks, over time, the measured energy value of the correlation results;

and improves the magnitude of the energy value using adjustments of at least one of the frequency or delay.

20. The apparatus of claim 19 wherein the measured energy forms an energy vector comprising energy from a plurality of delays and frequencies.

21. The apparatus of claim 19 wherein the plurality of correlators comprises a plurality of correlators measuring a correlation result having delay as a variable, a plurality of correlators measuring a correlation result having frequency as a variable, and a punctual correlator.

22. The apparatus of claim 21 wherein the plurality of correlators define a multi-dimensional correlation space representing an energy amount within the correlation results.

23. The apparatus of claim 21 wherein the plurality of correlators measuring a correlation result having delay as a variable comprise an early correlator having a delay that is earlier than a delay of the punctual correlator and a late correlator having a delay that is later than a delay of the punctual correlator, and wherein the plurality of correlators measuring a correlation result having frequency as a variable comprise a high correlator having a frequency that is higher than a frequency of the punctual correlator and a low correlator having a frequency that is lower than a frequency of the punctual correlator.

24. The apparatus of claim 19 wherein the energy value is a measured energy vector comprising a frequency quantity and a delay quantity.

25. The apparatus of claim 24 wherein the measured quantities are used to update states of an extended Kalman filter.