Systems, methods, and apparatus for jammer rejection

• US 20060222058A1
• Filed: 11/30/2005
• Published: 10/05/2006
• Est. Priority Date: 12/01/2004
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Simic, Emilija, Patrick, Christopher, Rowitch, Douglas
• Granted Patent: US 7,764,726 B2
• Time in Patent Office: Days
• US Class Current: 375/150
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 19/22 Multipath-related issues
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/34 Power consumption
• CPC Class Codes: H04B 1/7077 Multi-step acquisition, e.g. multi-dwell, coarse-fine or validation
• CPC Class Codes: H04K 3/228 Elimination in the received signal of jamming or of data corrupted by jamming interference suppression in receivers H04B1/10

Abstract

A method according to an embodiment obtains a list of peaks for each of a number of frequency hypotheses. Each peak has an energy result and corresponds to a code phase hypothesis. Embodiments include methods and apparatus that may be used in identifying a location of a signal (such as a GPS signal) in a two-dimensional search space. Location information may be further applied to operations such as signal acquisition, signal tracking, position location of a receiver, and timing operations such as the synchronization of one or more other processes.

Claims

1. A method of signal processing, said method comprising:

obtaining a plurality of results based on correlating a received code with a reference code, each result corresponding to one of a plurality of code phase hypotheses and one of a plurality of frequency hypotheses;

for each of the plurality of the frequency hypotheses, selecting a plurality of peaks among the results for the frequency hypothesis; and

for each of the plurality of the frequency hypotheses, storing an ordered list of the selected plurality of peaks.

2. The method of signal processing according to claim 1, wherein said selecting a plurality of peaks includes selecting a plurality of peaks according to energy values of the peaks.

3. The method of signal processing according to claim 1, wherein each of the lists is ordered according to energy values of the peaks in the list.

4. The method of signal processing according to claim 1, said method comprising rejecting a frequency hypothesis, said rejecting being based on the corresponding list.

5. The method of signal processing according to claim 4, wherein said rejecting is based on a relation between (A) a noise floor and (B) an energy value of a peak in the ordered list.

6. The method of signal processing according to claim 4, wherein said rejecting is based on a relation between (A) a noise floor and (B) the energy value of the peak having the greatest energy value in the ordered list.

7. The method of signal processing according to claim 4, wherein said rejecting is based on a relation between energy values of peaks in the ordered list.

8. The method of signal processing according to claim 4, wherein said rejecting is based on a determination that an energy value of a peak in the ordered list is within a threshold value of an energy value of another peak in the ordered list.

9. The method of signal processing according to claim 4, wherein said rejecting is based on a determination that a difference between the energy values of two peaks in the ordered list is not greater than a threshold value,

wherein one of the two peaks is the peak having the greatest energy value in the ordered list.

10. The method of signal processing according to claim 4, wherein said rejecting is based on a ratio of (A) an energy value of a peak in the ordered list to (B) a noise value,

wherein said noise value is based on values among the plurality of results for the frequency hypothesis, excluding those of the corresponding plurality of peaks.

11. The method of signal processing according to claim 4, wherein said rejecting includes:

calculating a sum of the results for the frequency hypothesis;

calculating a noise value for the frequency hypothesis, including subtracting a plurality of energy values from the sum; and

comparing the number of subtracted energy values to a threshold.

12. The method of signal processing according to claim 1, said method comprising:

selecting a peak in one of the ordered lists; and

calculating a pseudorange based on a code phase hypothesis corresponding to the selected peak.

13. The method of signal processing according to claim 12, said method comprising transmitting information based on the pseudorange to a network for wireless communications.

14. The method of signal processing according to claim 1, said method comprising:

selecting a best maximum peak from one of the ordered lists;

selecting a peak from the ordered list that corresponds to an earlier code hypothesis than the best maximum peak; and

calculating a pseudorange based on the earlier code hypothesis.

15. The method of signal processing according to claim 1, wherein the received code is obtained from a signal received from a space vehicle of a global positioning system.

16. The method of signal processing according to claim 15, said method comprising rejecting a peak in one of the ordered lists, said rejecting being based on a location in frequency of a signal received from another space vehicle of the global positioning system.

17. A data storage medium having machine-readable instructions describing the method of signal processing according to claim 1.

18. An apparatus for signal processing, said apparatus comprising:

a first array of logic elements configured to obtain a plurality of results based on correlating a received code with a reference code, each result corresponding to one of a plurality of code phase hypotheses and one of a plurality of frequency hypotheses; and

a second array of logic elements configured to select, for each of a plurality of the frequency hypotheses, a plurality of peaks among the results for the frequency hypothesis and to store, for each of a plurality of the frequency hypotheses, an ordered list of the selected plurality of peaks.

19. The apparatus for signal processing according to claim 18, wherein said first array includes a correlator.

20. The apparatus for signal processing according to claim 19, said apparatus comprising a searcher that includes the first array, said searcher comprising a plurality of correlators.

21. The apparatus for signal processing according to claim 18, said apparatus comprising a means for searching that includes the first array.

22. The apparatus for signal processing according to claim 18, wherein at least a portion of the first array and at least a portion of the second array are on the same chip.

23. The apparatus for signal processing according to claim 18, wherein the second array is configured to calculate, for each of the plurality of frequency hypotheses, a noise value, and

wherein each of said noise values is based on values among the plurality of results for the frequency hypothesis, excluding those of the corresponding plurality of peaks.

24. The apparatus for signal processing according to claim 18, wherein the apparatus is configured to transmit, over a wireless communications channel, information based on a code phase hypothesis corresponding to a peak in one of the ordered lists.

25. The apparatus for signal processing according to claim 18, said apparatus comprising a third array of logic elements configured to determine, for at least one of the frequency hypotheses, a relation between energy values of peaks in the corresponding ordered list and to reject the frequency hypothesis based on the determined relation.

26. The apparatus for signal processing according to claim 25, wherein the third array is configured to select a peak in one of the ordered lists and to calculate a pseudorange based on a code phase hypothesis corresponding to the selected peak.

27. The apparatus for signal processing according to claim 18, said apparatus comprising a third array of logic elements configured to determine, for at least one of the frequency hypotheses, a relation between (A) a noise floor and (B) an energy value of a peak in the ordered list and to reject the frequency hypothesis based on the determined relation.

28. An apparatus for signal processing, said apparatus comprising:

means for correlating a received code with a reference code to obtain a plurality of results, each result corresponding to one of a plurality of code phase hypotheses and one of a plurality of frequency hypotheses; and

an array of logic elements configured to select, for each of a plurality of the frequency hypotheses, a plurality of peaks obtained from the results for the frequency hypothesis and to store an ordered list of the selected plurality of peaks.

29. The apparatus for signal processing according to claim 28, wherein the array of logic elements is configured to calculate, for each of the plurality of frequency hypotheses, a noise value, and

wherein each of said noise values is based on values among the plurality of results for the frequency hypothesis, excluding those of the corresponding plurality of peaks.

30. The apparatus for signal processing according to claim 28, wherein the apparatus is configured to transmit, over a wireless communications channel, information based on a code phase hypothesis corresponding to a peak in one of the ordered lists.

31. The apparatus for signal processing according to claim 28, said apparatus comprising a second array of logic elements configured to determine, for at least one of the frequency hypotheses, a relation between energy values of peaks in the corresponding ordered list and to reject the frequency hypothesis based on the determined relation.

32. The apparatus for signal processing according to claim 31, wherein the second array is configured to select a peak in one of the ordered lists and to calculate a pseudorange based on a code phase hypothesis corresponding to the selected peak.

33. The apparatus for signal processing according to claim 28, said apparatus comprising a second array of logic elements configured to determine, for at least one of the frequency hypotheses, a relation between (A) a noise floor and (B) an energy value of a peak in the ordered list and to reject the frequency hypothesis based on the determined relation.