System and method for detection and tracking of targets

• US 7,218,274 B2
• Filed: 10/21/2003
• Issued: 05/15/2007
• Est. Priority Date: 06/06/2000
• Status: Expired due to Fees

• Current Assignee: Signal Labs Incorporated
• Original Assignee: Signal Labs Incorporated
• Inventors: Arikan, Orhan, Ozdemir, Ahmet Kemal
• Primary Examiner(s): Gregory; Bernarr E.
• Application Number:
  US10/691,245
• Publication Number:
  US 20040085241A1
• Time in Patent Office: 1,302 Days
• Field of Search: 342/27, 342/28, 342 89-112, 342/115, 342/118, 342127-137, 342/175, 342189-197, 342 13- 20, 367 87- 95, 367 99-102, 708/4
• US Class Current: 342/195
• CPC Class Codes: G01S 13/524 based upon the phase or frequency shift resulting from movement of objects, with reference to the transmitted signals, e.g. coherent MTi
• CPC Class Codes: G01S 7/295 Means for transforming co-ordinates or for evaluating data, e.g. using computers

Abstract

System and method for detection and tracking of targets, which in a preferred embodiment is based on the use of fractional Fourier transformation of time-domain signals to compute projections of the auto and cross ambiguity functions along arbitrary line segments. The efficient computational algorithms of the preferred embodiment are used to detect the position and estimate the velocity of signals, such as those encountered by active or passive sensor systems. Various applications of the proposed algorithm in the analysis of time-frequency domain signals are also disclosed.

Claims

1. A signal processing system comprising:

a signal receiver;

a first processor operable to compute one or more projections of the magnitude squared auto-ambiguity function of a received modulated signal; and

a second processor operable to determine a modulation type of the received signal based on the computed one or more projections.

2. The system of claim 1 further comprising a memory for storing one or more previously computed signatures of projections of the magnitude squared auto-ambiguity function of one or more know signals, and the second processor is further operable to determine the modulation type of the received signal by computing signatures of the one or more projections of the received signal, and comparing the signatures of the projections of the received signal to the previously computed signatures of the known signals.

3. The system of claim 1, wherein the signal receiver is capable of receiving one or both of:

continuous waveform signals and discrete-time signals.

4. A computer program product comprising:

a medium with instructions stored thereon that cause a computer system to

(a) receive a signal;

(b) compute one or more projections of the magnitude squared auto-ambiguity function of the received signals; and

(c) determine a modulation type of the received signal based on the computed projections.

5. The computer program product of claim 4, having the medium further stored thereon instructions that cause the computer system to compute projection signatures in the magnitude squared ambiguity function domain of at least one known signal.

6. The computer program product of claim 5 having the medium further stored thereon instructions that cause the computer system to store said projection signatures.

7. The computer program product of claim 6, wherein instructions that causes the computer system to determine the modulation type of the received signal, comprise instructions that cause the computer system:

(i) compute signatures of the one or more projections of the received signal; and

(ii) compare the stored projection signatures to the computed signatures of the one or more projections of the received signals.

8. The computer program product of claim 4, having the medium further stored thereon instructions that cause the computer system to determine one or more properties of the received signal in addition to its modulation type.

9. The computer program product of claim 8, wherein the determined properties include one or more of a time of arrival of the received signal, an amplitude of the received signal, and a duration of the received signal.

10. The computer program product of claim 9, having the medium further stored thereon instructions that cause the computer system to characterize a source of the received signal based on the determined modulating type.

11. A signal processing method comprising the steps of:

receiving a modulated signal;

computing one or more projections of the magnitude squared auto-ambiguity function of the received signal; and

determining a modulation type of the received signal based on the one or more computed projections.

12. The method of claim 11 further comprising the step of selecting a projection of the magnitude squared auto-ambiguity function from the one or more projections of the magnitude squared auto-ambiguity function, wherein the projection is selected on the basis of peaks of the magnitude squared auto-ambiguity function.

13. The method of claim 11, wherein the receive signal is a continuous waveform signal.

14. The method of claim 11, wherein the received signal is a discrete-time signal.

15. The method of claim 11 further comprising the step of computing projection signatures in the magnitude squared ambiguity function domain of at least one known signal.

16. The method of claim 15 further comprising the step of storing said projection signatures.

17. The method of claim 16, wherein the step of determining the modulation type of the received signal comprises:

computing signatures of the one or more projections of the received signal; and

comparing the stored projection signatures to the computed signatures of the one or more projections of the received signals.

18. The method of claim 11 further comprising the step of determining one or more properties of the received signal in addition to its modulation type.

19. The method of claim 18, wherein the determined properties include one or more of:

a time of arrival of the received signal, an amplitude of the received signal, and a duration of the received signal.

20. The method of claim 11 further comprising the step of characterizing a source of the received signal based on the determined modulation type.