Method for selecting signals of opportunity for passive coherent location

• US 10,620,292 B2
• Filed: 09/06/2017
• Issued: 04/14/2020
• Est. Priority Date: 09/06/2017
• Status: Active Grant

• Current Assignee: the united states of america as represented by the secretary of the navy
• Original Assignee: The United States of America As Represented By The Secretary of Agriculture
• Inventors: Johnson, Nicholas T., Chergui, Mohammed, Rockway, John D., Sternberg, Oren
• Primary Examiner(s): Diallo, Mamadou L
• Application Number:
  US15/696,483
• Publication Number:
  US 20190072634A1
• Time in Patent Office: 951 Days
• CPC Class Codes: G01S 1/14 using amplitude comparison of signals transmitted simultaneously from antennas or antenna systems having differently oriented overlapping directivity-characteristics
• CPC Class Codes: G01S 1/38 using comparison of [1] the phase of the envelope of the change of frequency, due to Doppler effect, of the signal transmitted by an antenna moving, or appearing to move, in a cyclic path with [2] the phase of a reference signal, the frequency of this reference signal being synchronised with that of the cyclic movement, or apparent cyclic movement, of the antenna
• CPC Class Codes: G01S 13/003 Bistatic radar systems; Multistatic radar systems
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: G01S 5/0284 Relative positioning

Abstract

A signal evaluation system is provided for evaluating a first EM signal and a second EM signal for use in a passive coherent location system. The signal evaluation system includes: a spectrum detecting component that detects the first EM signal and the second EM signal; a signal characterization component that generates a first characterization of the first EM signal and to generate a second characterization of the second EM signal; and a ranking component that ranks the EM signals for use in the passive coherent location system. The first characterization is based on an amplitude associated with the first EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the first EM signal. The second characterization is based on an amplitude associated with the second EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the second EM signal.

Claims

1. A signal evaluation system for evaluating a first EM signal and a second EM signal for use in a passive coherent location system, said signal evaluation system comprising:

spectrum detecting component operable to detect the first EM signal and the second EM signal within an electromagnetic spectrum;

a signal characterization component operable to generate a first characterization associated with the first EM signal and to generate a second characterization associated with the second EM signal; and

a ranking component operable to rank the first EM signal with reference to the second EM signal for use in the passive coherent location system based on the first characterization and the second characterization,

wherein the first characterization is based on an amplitude associated with the first EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the first EM signal, and

wherein the second characterization is based on an amplitude associated with the second EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the second EM signal.

2. The signal evaluation system of claim 1,

wherein said signal characterization component comprises an amplitude detector and an amplitude comparator,

wherein said amplitude detector is operable to detect a first amplitude associated with the first EM signal and to detect a second amplitude associated with the second EM signal,

wherein said amplitude comparator is operable to generate a first amplitude comparison based on the first amplitude and a predetermined amplitude threshold and to generate a second amplitude comparison based on the second amplitude and the predetermined amplitude threshold.

3. The signal evaluation system of claim 2, wherein signal characterization component comprises an ambiguity function generator operable to generate a first ambiguity function associated with the first EM signal and to generate a second ambiguity function associated with the second EM signal.

4. The signal evaluation system of claim 3, wherein said ambiguity function generator further comprises an autocorrelator operable to autocorrelate the first EM signal and to autocorrelate the second EM signal.

5. The signal evaluation system of claim 4, wherein said ambiguity function generator is further operable to generate a first ideal ambiguity function associated with the first EM signal and to generate a second ideal ambiguity function associated with the second EM signal.

6. The signal evaluation system of claim 5,

wherein said ambiguity function generator is further operable to generate a first ideal ambiguity function associated with the first EM signal and to generate a second ideal ambiguity function associated with the second EM signal,

wherein the first ideal ambiguity function represents perfect autocorrelation of the first EM signal, and

wherein the second ideal ambiguity function represents perfect autocorrelation of the second EM signal.

7. The signal evaluation system of claim 6, further comprising:

a distance metric calculating component operable to calculate a first distance metric and a second distance metric,

wherein the first distance metric is based on a relationship between the first ambiguity function and the first ideal ambiguity function, and

wherein the second distance metric is based on a relationship between the second ambiguity function and the second ideal ambiguity function.

8. The signal evaluation system of claim 7,

wherein the first distance metric comprises a difference between the first ambiguity function and the first ideal ambiguity function, and

wherein the second distance metric comprises a difference between the second ambiguity function and the second ideal ambiguity function.

9. The signal evaluation system of claim 1, wherein said signal characterization component comprises an ambiguity function generator operable to generate a first ambiguity function associated with the first EM signal and to generate a second ambiguity function associated with the second EM signal.

10. The signal evaluation system of claim 9, wherein said ambiguity function generator further comprises an autocorrelator operable to autocorrelate the first EM signal with itself and to autocorrelate the second EM signal.

11. The signal evaluation system of claim 10, wherein said ambiguity function generator is further operable to generate a first ideal ambiguity function associated with the first EM signal and to generate a second ideal ambiguity function associated with the second EM signal.

12. The signal evaluation system of claim 11,

wherein said ambiguity function generator is further operable to generate a first ideal ambiguity function associated with the first EM signal and to generate a second ideal ambiguity function associated with the second EM signal,

wherein the first ideal ambiguity function represents perfect autocorrelation of the first EM signal, and

wherein the second ideal ambiguity function represents perfect autocorrelation of the second EM signal.

13. The signal evaluation system of claim 12, further comprising:

a distance metric calculating component operable to calculate a first distance metric and a second distance metric,

wherein the first distance metric is based on a relationship between the first ambiguity function and the first ideal ambiguity function, and

wherein the second distance metric is based on a relationship between the second ambiguity function and the second ideal ambiguity function.

14. The signal evaluation system of claim 13,

wherein the first distance metric comprises a difference between the first ambiguity function and the first ideal ambiguity function, and

wherein the second distance metric comprises a difference between the second ambiguity function and the second ideal ambiguity function.

15. A signal evaluation method for evaluating a first EM signal and a second EM signal for use in a passive coherent location system, said signal evaluation method comprising:

detecting, via spectrum detecting component, the first EM signal and the second EM signal within an electromagnetic spectrum;

generating, via a signal characterization component, a first characterization associated with the first EM signal;

generating, via the signal characterization component, a second characterization associated with the second EM signal; and

ranking, via a ranking component, the first EM signal with reference to the second EM signal for use in the passive coherent location system based on the first characterization and the second characterization,

wherein the first characterization is based on an amplitude associated with the first EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the first EM signal, and

wherein the second characterization is based on an amplitude associated with the second EM signal and one of range resolution, Doppler resolution, and combinations thereof associated with the second EM signal.

16. The signal evaluation method of claim 15,

wherein said generating, via a signal characterization component, a first characterization associated with the first EM signal comprises detecting, via an amplitude detector a first amplitude associated with the first EM signal,

wherein said generating, via the signal characterization component, a second characterization associated with the second EM signal comprises detecting, via the amplitude detector, a second amplitude associated with the second EM signal,

wherein said generating, via a signal characterization component, a first characterization associated with the first EM signal further comprises generating, via an amplitude comparator, a first amplitude comparison based on the first amplitude and a predetermined amplitude threshold, and

wherein said generating, via the signal characterization component, a second characterization associated with the second EM signal further comprises generating, via the amplitude comparator, a second amplitude comparison based on the second amplitude and the predetermined amplitude threshold.

17. The signal evaluation method of claim 16,

wherein said generating, via a signal characterization component, a first characterization associated with the first EM signal further comprises generating, via an ambiguity function generator, a first ideal ambiguity function associated with the first EM signal, and

wherein said generating, via the signal characterization component, a second characterization associated with the second EM signal further comprises generating, via the ambiguity function generator, a second ideal ambiguity function associated with the second EM signal.

18. The signal evaluation method of claim 17,

wherein said generating, via an ambiguity function generator, a first ideal ambiguity function comprises autocorrelating, via an autocorrelator, the first ambiguity function associated with the first EM signal, and

wherein generating, via the ambiguity function generator, a second ideal ambiguity function comprises autocorrelating, via an autocorrelator, the second ambiguity function associated with the second EM signal.

19. The signal evaluation method of claim 18, further comprising:

calculating, via a distance metric calculating component, a first distance metric; and

calculating, via the distance metric calculating component, a second distance metric,

wherein the first distance metric is based on a relationship between the first ambiguity function and the first ideal ambiguity function, and

wherein the second distance metric is based on a relationship between the second ambiguity function and the second ideal ambiguity function.