Methods and apparatus for automatic STC from sea state measurement via radar sea clutter eccentricity

• US 8,456,352 B2
• Filed: 12/17/2010
• Issued: 06/04/2013
• Est. Priority Date: 12/17/2010
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Wood, Thomas E.
• Primary Examiner(s): Barker, Matthew M
• Application Number:
  US12/971,707
• Publication Number:
  US 20120154208A1
• Time in Patent Office: 900 Days
• Field of Search: 342159-164, 342/205
• US Class Current: 342/205
• CPC Class Codes: G01S 7/12 Plan-position indicators, i.e. P.P.I.
• CPC Class Codes: G01S 7/34 Gain of receiver varied automatically during pulse-recurrence period, e.g. anti-clutter gain control
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter

Abstract

Methods and apparatus to receive radar return information from signals transmitted by a radar, process the radar return information to identify sea clutter, process the sea clutter to fit an ellipse to arrange horizon of the sea clutter as a function of azimuth to determine a sea state, and select sensitivity time control (STC) attenuation of the sea clutter based upon the sea state.

Claims

1. A method, comprising:

receiving radar return information from signals transmitted by a radar;

processing the radar return information to identify sea clutter;

processing, using a processor, the sea clutter to fit an ellipse to a range horizon of the sea clutter as a function of azimuth to determine a sea state; and

selecting sensitivity time control (STC) attenuation of the sea clutter based upon the sea state.

2. The method according to claim 1, further including varying STC attenuation by azimuth.

3. The method according to claim 1, further including determining a maximum sea clutter range for sectors in a radar scan.

4. The method according to claim 3, further including substituting data for a compromised one of the sectors.

5. The method according to claim 1, further including modeling sea clutter using a cubic polynomial.

6. The method according to claim 1, further including determining a direction for the sea state based upon at least one parameter of the ellipse.

7. The method according to claim 6, further including generating an alert when the sea clutter range horizon does not fit an ellipse to predetermined criteria.

8. The method according to claim 1, further including generating an alert when the range horizon for the sea clutter cannot be determined.

9. The method according to claim 1, further including determining the direction for the sea state from a direction of the major axis of the ellipse.

10. The method according to claim 1, further including determining the sea state from an eccentricity of the ellipse.

11. The method according to claim 1, further including mapping at least one parameter of the ellipse to sea states.

12. The method according to claim 1, further including using a Fourier Transform to determine one or more parameters of the ellipse.

13. The method according to claim 1, further including using least means square data fitting to the ellipse.

14. A non-transitory computer readable medium having instructions stored thereon which when executed by a processor cause a machine to:

receive radar return information from signals transmitted by a radar;

process the radar return information to identify sea clutter;

process the sea clutter to fit an ellipse to a range horizon of the sea clutter as a function of azimuth to determine a sea state; and

select sensitivity time control (STC) attenuation of the sea clutter based upon the sea state.

15. The computer readable medium according to claim 14, further including instructions for varying the STC attenuation by azimuth.

16. The computer readable medium according to claim 14, further including instructions for determining a direction for the sea state based upon at least one parameter of the ellipse.

17. The computer readable medium according to claim 14, further including instructions for determining the sea state from an eccentricity of the ellipse.

18. A radar system comprising:

an antenna to receive radar return;

a sensitivity time control (STC) module configured to provide STC attenuation of the radar return, the STC module including a sea clutter module configured to determine sea clutter including a sea clutter range horizon as a function of azimuth and a sea state module configured to determine a sea state by fitting the sea clutter range horizon to an ellipse; and

a display configured to enable a user to perceive radar return information.

19. The system according to claim 18, wherein the STC module is configured to automatically select the STC attenuation based upon the sea state.

20. The system according to claim 19, wherein the STC attenuation varies by azimuth.

21. The system according to claim 18, wherein the STC module is configured to determine direction for the sea state.

22. The system according to claim 18, wherein the sea state module is configured to determine the sea state from at least one parameter of the ellipse.