Signal detector employing correlation analysis of non-uniform and disjoint sample segments

• US 6,636,178 B2
• Filed: 10/04/2001
• Issued: 10/21/2003
• Est. Priority Date: 03/30/1999
• Status: Expired due to Term

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Gronemeyer, Steven A.
• Primary Examiner(s): Gregory, Bernarr E.
• Application Number:
  US09/971,293
• Publication Number:
  US 20020041252A1
• Time in Patent Office: 747 Days
• Field of Search: 342/357-1-3, 342/378, 375/130, 375/140-153, 375/229-236, 375/340-343
• US Class Current: 342/378
• 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

Abstract

A signal detector is provided in which correlation analyses of multiple segments of a received signal from separate and distinct periods of time are combined to improve the detection capability of the signal detector. In one embodiment, the signal detector is part of a GPS receiver.

Claims

1. A system for detecting signals including a signal detector comprising:

a receiver for receiving at least a first segment of a signal and a second segment of the signal, the first and second segments of the signal representing separate periods of time, wherein the signal comprises a signal of interest perturbed by noise or pseudo-noise;

a correlator coupled to the receiver for deriving first correlation data, representative of the correlation between the first segment and a hypothesis, and second correlation data representative of the correlation between the second segment and the hypothesis, said correlator generating said hypothesis; and

a combiner coupled to the correlator for determining a parameter difference between the first and second correlation data, for adjusting a selected one of the first and second correlation data responsive to the parameter difference, and combining the adjusted data with the other of the first and second correlation data to obtain cumulative correlation data useful for detecting at least a parameter of the signal of interest.

2. The signal detector of claim 1 in which the receiver is an RF receiver.

3. The signal detector of claim 1 in which the signal of interest is a carrier signal modulated with a repeating PN code.

4. The signal detector of claim 1 in which the correlator is a matched filter.

5. The signal detector of claim 1 in which the combiner is a processor.

6. The signal detector of claim 1 in which the parameter difference is a code phase difference, and the combiner adjusts the selected one of the first and second correlation data responsive to the code phase difference.

7. The signal detector of claim 1 in which the combiner successively combines the correlation data for successive segments until the signal of interest or a parameter of the signal of interest can be accurately and reliably detected.

8. The signal detector of claim 7 in which the parameter of the signal of interest is the code phase of the signal.

9. The signal detector of claim 7 in which the parameter of the signal of interest is the presence of the signal.

10. A signal detector comprising:

a receiver for receiving a first segment of a signal and a second segment of the signal, the signal representative of a plurality of signals of interest, each signal of interest representative of a repeating PN code modulated onto a carrier signal, and the first and second segments representing periods of time;

a correlator coupled to the receiver for deriving first correlation data representative of the correlation between the first segment and a combined PN code and code phase hypotheses, and second correlation data representative of the correlation between the second segment and the combined PN code and code phase hypothesis;

a combiner coupled to the correlator for determining a code phase difference between portions of the first and second correlation data corresponding to the PN code hypothesis, for adjusting a selected one of the portions of the first and second correlation data responsive to the code phase difference, combining the adjusted data with the other portion to obtain cumulative correlation data useful for detecting a signal of interest or a parameter of a signal of interest, and generating said code phase hypothesis.

11. The signal detector of claim 10 wherein said correlator comprises a match filter.

12. A method for detecting a signal comprising:

receiving a first segment of a signal, and a second segment of the signal, the signal comprising a signal of interest perturbed by noise or pseudo-noise, and the first and second segments representing periods of time;

generating a hypothesis;

deriving first correlation data representative of the correlation between the first segment and the hypothesis, and second correlation data representative of the correlation between the second segment and the hypothesis;

determining a parameter difference between the first and second correlation data;

adjusting a selected one of the first and second correlation data responsive to the parameter difference; and

combining the adjusted data with the other of the first and second correlation data to obtain cumulative correlation data useful for detecting the signal of interest or a parameter of the signal of interest.

13. A method for detecting a signal comprising:

receiving a first segment of a signal and a second segment of the signal, the signal representative of a plurality of signals of interest, each signal of interest representative of a repeating PN code modulated onto a carrier signal, the first and second segments representing periods of time;

generating a code phase hypothesis;

deriving first correlation data representative of the correlation between the first segment and a combined PN code and code phase hypothesis, and second correlation data representative of the correlation between the second segment and the combined PN code and the code phase hypothesis;

determining a code phase difference between portions of the first and second correlation data corresponding to the PN code hypothesis;

adjusting a selected one of the portions of the first and second correlation data responsive to the code phase difference; and

combining the adjusted data with the other portion to obtain cumulative correlation data useful for detecting a signal of interest or a parameter of a signal of interest.

14. A signal detector comprising:

means for receiving a signal of interest comprising a first segment and a second segment of said signal of interest, each segment representing a period of time;

means for correlating a first correlation data corresponding to a first correlation between said first segment and a hypothesis, for deriving a second correlation data corresponding to a second correlation between said second segment and said hypothesis, and for generating said hypothesis;

means for determining a parameter difference between said first and said second correlation data;

means for adjusting a selected one of said first and said second correlation data in response to said parameter difference to determine an adjusted data; and

means for combining said adjusted data with the non-selected correlation data for generating a cumulative correlation data for detecting said signal of interest.

15. A signal detector, comprising:

a receiver to detect a first segment of a signal of interest and a second segment of said signal of interest, and said first segment and said second segment representing periods of time;

a correlator, coupled to the receiver, to derive a first correlation data representative of the correlation between the first segment and a hypothesis, to derive a second correlation data representative of the correlation between the second segment and said hypothesis, and to generate said hypothesis;

a parameter determiner, coupled to the correlator, to determine a parameter difference between said first and said second correlation data;

a processor, coupled to said parameter determiner, to adjust a selected one of the first and second correlation data responsive to the parameter difference to determine an adjusted data; and

a combiner, coupled to the adjuster, to combine the adjusted data with the non-selected correlation data to generate cumulative correlation data useful for detecting said signal of interest.

16. The signal detector of claim 15, wherein said correlator comprises a matched filter.

17. A method for detecting a signal of interest comprising the steps of:

receiving a first segment of a signal of interest;

receiving a second segment of said signal of interest;

generating a hypothesis;

deriving a first correlation data representative of the correlation between said first segment and said hypothesis;

deriving a second correlation data representative of the correlation between said second segment and said hypothesis;

determining a parameter difference between said first and said second correlation data;

selecting one of said first and said second correlation data;

adjusting said selected correlation data in response to said parameter difference to determine an adjusted data; and

combining said adjusted data with the non-selected correlation data to determine a cumulative correlation data for detecting said signal of interest.

18. Computer readable media having a program for storing a series of instructions for detecting a signal of interest, the program for performing at least the following:

receiving a first segment of a signal of interest;

receiving a second segment of said signal of interest, such that said first segment and said second segment represent periods of time;

generating a hypothesis;

deriving a first correlation data representative of the correlation between said first segment and said hypothesis;

deriving a second correlation data representative of the correlation between said second segment and said hypothesis;

determining a parameter difference between said first and said second correlation data;

selecting one of said first and said second correlation data;

adjusting said selected correlation data in response to said parameter difference to determine an adjusted data; and

combining said adjusted data with the non-selected correlation data to determine a cumulative correlation data useful for detecting said signal of interest.