Methods and apparatus for log-FTC radar receivers having enhanced sea clutter model

• US 7,796,082 B2
• Filed: 02/08/2007
• Issued: 09/14/2010
• Est. Priority Date: 02/08/2007
• Status: Active Grant

• Current Assignee: Raytheon Company (Rtx Corporation)
• Original Assignee: Raytheon Company (Rtx Corporation)
• Inventors: Wood, Thomas E.
• Primary Examiner(s): Gregory; Bernarr E
• Application Number:
  US11/672,813
• Publication Number:
  US 20080191929A1
• Time in Patent Office: 1,314 Days
• Field of Search: 342 26 R- 26 D, 342 89-103, 342159-164, 342/175, 342/195, 342/196, 342/205, 342200-204
• US Class Current: 342/205
• CPC Class Codes: G01S 13/937 of marine craft
• CPC Class Codes: G01S 13/956 mounted on ship or other platform
• 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
• CPC Class Codes: Y02A 90/10 Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

Abstract

Methods and apparatus to provide Log-Amp-detected radar sea clutter voltage modeled by a polynomial, such as a cubic polynomial, and using that model as a basis for sea clutter reduction filtering. In an exemplary embodiment, a navigational radar includes an STC filter design based on the cubic sea clutter modeling.

Claims

1. A method, comprising:

receiving signal return for a transmitted signal;

processing the received signal return non-coherently including using a sea clutter model that models sea clutter voltage over range with a cubic polynomial;

using the processed signal for target tracking; and

outputting the processed signal return.

2. The method according to claim 1, further including displaying the processed signal return and the modeled sea clutter.

3. The method according to claim 1, wherein the cubic polynomial includes coefficients corresponding to physical parameters.

4. The method according to claim 1, wherein the cubic polynomial model C(r), where r is range, for navigation sea clutter voltage is a cubic with a 3^rd order solution to the equation C(r)=μ

, wherein μ

is mean receiver noise level;

$C<br><br>\left(r\right)=\mathrm{\mu <br><br>}+\frac{\left(\mathrm{\xi <br><br>}-\mathrm{\mu <br><br>}\right)}{h^3}<br><br>{\left(h-r\right)}^3,$

where, μ

, ξ

, and h are all non-negative, the maximum range extent of sea clutter is represented by h, μ

is the mean receiver noise level, and ξ

=C(0)is the maximum clutter return.

5. The method according to claim 4, further including truncation of the cubic polynomial at a point h, where sea clutter meets mean noise level.

6. The method according to claim 5, further including changing one or more of the coefficients based upon sea state information.

7. The method according to claim 6, further including altering h based upon wind information.

8. The method according to claim 4, further including providing four-parameter sensitivity time control (STC) in which three parameters correspond to the three polynomial coefficients and a fourth parameter corresponds to an attack point, which is a function of attenuation and detection sensitivity.

9. The method according to claim 8, further including performing subtractive STC.

10. The method according to claim 8, further including performing attack-point-based multiplicative STC.

11. The method according to claim 1, where the cubic polynomial has the form C(r)=(a+br+cr²)(d−

r), where the quadratic term is irreducible.

12. The method according to claim 1, wherein the step of outputting includes displaying via plan position indicator.

13. An article, comprising:

a computer readable medium containing stored instructions to enable a computer to perform;

receiving signal return for a transmitted signal;

processing the received signal return non-coherently including using a sea clutter model that models sea clutter voltage over range with a cubic polynomial using the processed signal for target tracking; and

outputting the processed signal return.

14. The article according to claim 13, further including instructions for displaying the processed signal return and the modeled sea clutter.

15. The article according to claim 13, wherein the cubic polynomial includes coefficients corresponding to physical parameters.

16. The article according to claim 13, wherein the cubic polynomial model C(r), where r is range, for navigation sea clutter voltage is a cubic with a 3^rd order solution to the equation C(r)=μ

, wherein μ

is mean receiver noise level;

$C<br><br>\left(r\right)=\mathrm{\mu <br><br>}+\frac{\left(\mathrm{\xi <br><br>}-\mathrm{\mu <br><br>}\right)}{h^3}<br><br>{\left(h-r\right)}^3,$

where, μ

, ξ

, and h are all non-negative, the maximum range extent of sea clutter is represented by h, μ

is the mean receiver noise level, and ξ

=C(0) is the maximum clutter return.

17. The article according to claim 16, further including providing four-parameter sensitivity time control (STC) in which three parameters correspond to the three polynomial coefficients and a fourth parameter corresponds to an attack point, which is a function of attenuation and detection sensitivity.

18. A radar system, comprising:

a receiver to receive signal return for a transmitted signal;

a signal processing module to non-coherently process the signal return;

a sea clutter modeling module to model sea clutter over range with a cubic polynomial for the signal return; and

a display to display information corresponding to the processed signal return.

19. The system according to claim 18, wherein the cubic polynomial model C(r), where r is range, for navigation sea clutter voltage is a cubic with a 3^rd order solution to the equation C(r)=μ

, wherein μ

is mean receiver noise level;

$C<br><br>\left(r\right)=\mathrm{\mu <br><br>}+\frac{\left(\mathrm{\xi <br><br>}-\mathrm{\mu <br><br>}\right)}{h^3}<br><br>{\left(h-r\right)}^3.$

where, μ

, ξ

, and h are all non-negative, the maximum range extent of sea clutter is represented by h, μ

is the mean receiver noise level, and ξ

=C(0) is the maximum clutter return.

20. The system according to claim 18, further including a four-parameter sensitivity time control (STC) in which three parameters correspond to the three polynomial coefficients and a fourth parameter corresponds to an attack point, which is a function of attenuation and detection sensitivity.