Monopulse radar processor for resolving two sources

• US 6,356,231 B1
• Filed: 06/29/2000
• Issued: 03/12/2002
• Est. Priority Date: 06/29/2000
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Zheng, Yibin, Yu, Kai-Bor
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US09/607,146
• Time in Patent Office: 621 Days
• Field of Search: 342/80, 342/149, 342/150, 342/151, 342/152, 342/147, 342/195
• US Class Current: 342/149
• CPC Class Codes: G01S 13/44 Monopulse radar, i.e. simultaneous lobing
• CPC Class Codes: G01S 13/4427 with means for eliminating the target-dependent errors in angle measurements, e.g. glint, scintillation effects
• CPC Class Codes: G01S 3/32 derived from different combinations of signals from separate antennas, e.g. comparing sum with difference

Abstract

A method and system for identifying the locations of plural targets lying within the main beam of a monopulse antenna including four ports for generating sum, elevation difference, azimuth difference, and double difference signals. The method comprises the steps of processing the sum, elevation difference, azimuth difference, and double difference signals in accordance with a series of linear equations to obtain a set of intermediate values; and processing the set of intermediate values in accordance with a set of algebraic equations to obtain signals representing an angular direction of each of the plural targets. Preferably, the method further includes the step of processing the sum, elevation difference, azimuth difference and double difference signals and the signals representing the angular directions of the targets according to a further set of algebraic equations to obtain signals representing the amplitude of the beam reflected from each of the targets. Also, in a preferred embodiment, the signals representing the angular direction of the targets include signals representing, for each of the targets, an angular direction of the target in an x-plane, and an angular direction of the target in a y-plane.

Claims

1. A method for identifying the locations of plural targets lying within the main beam of a monopulse antenna including at least four ports for generating sum, elevation difference, azimuth difference, and double difference signals, the method comprising the steps of:

processing the sum, elevation difference, azimuth difference, and double difference signals in accordance with a series of linear equations to obtain a set of intermediate values; and

processing the set of intermediate values in accordance with a set of algebraic equations to obtain signals representing an angular direction of each of the plural targets.

2. A method according to claim 1, further including the step of processing the sum, elevation difference, azimuth difference and double difference signals and the signals representing the angular directions of the targets according to a further set of algebraic equations to obtain signals representing the amplitude of the beam reflected from each of the targets.

3. A method according to claim 1, wherein the signals representing the angular direction of the targets include signals representing, for each of the targets, an angular direction of the target in an x-plane, and an angular direction of the target in a y-plane.

4. A method according to claim 1, wherein said set of linear equations include:

5. A method according to claim 1, wherein said set of algebraic equations includes:

$T_{x,1}=\frac{\left(A-D\right)+\sqrt{{\left(A-D\right)}^2-4<br><br>E<br><br>\text{\hspace{1em}<br><br>}<br><br>B}}{2<br><br>B}$$T_{y,1}=\frac{B<br><br>\text{\hspace{1em}<br><br>}<br><br>T_{x,1}-A}{C}$$T_{x,2}=\frac{\left(A-D\right)-\sqrt{{\left(A-D\right)}^2-4<br><br>E<br><br>\text{\hspace{1em}<br><br>}<br><br>B}}{2<br><br>B}$$T_{y,2}=\frac{B<br><br>\text{\hspace{1em}<br><br>}<br><br>T_{x,2}-A}{C}$

where;

T_x,1, T_y,1, T_x,2, T_y,2 are the signals representing the angular directions of the targets; and

A, B, C, D, E and F comprise the set of intermediate values.

6. A method according to claim 2, wherein said further set of algebraic equations includes:

${\mathrm{\Sigma <br><br>}}_1=\frac{\sum <br><br>T_{x,2}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Delta <br><br>}}_{\mathrm{az}}}{T_{x,2}-T_{x,1}}$${\mathrm{\Sigma <br><br>}}_2=\frac{\sum <br><br>T_{x,1}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Delta <br><br>}}_{\mathrm{az}}}{T_{x,1}-T_{x,2}}$

where;

Σ

₁ and Σ

_z represent the amplitudes of the beam reflected respectively, from a first and from a second of the targets; and

T_x,1, T_y,1, T_x,2 and T_y,2 are the signals representing the angular directions of the targets.

7. A processing system for identifying the locations of plural targets lying within the main beam of a monopulse antenna including four ports for generating sum, elevation difference, azimuth difference, and double difference signals, the processing system comprising:

a first processing section for processing the sum, elevation difference, azimuth difference, and double difference signals in accordance with a series of linear equations to obtain a set of intermediate values; and

a second processing section for processing the set of intermediate values in accordance with a set of algebraic equations to obtain signals representing an angular direction of each of the plural targets.

8. A processing system according to claim 7, further including a third processing section for processing the sum, elevation difference, azimuth difference and double difference signals and the signals representing the angular directions of the targets according to a further set of algebraic equations to obtain signals representing the amplitude of the beam reflected from each of the targets.

9. A processing system according to claim 7, wherein the signals representing the angular direction of the targets include signals representing, for each of the targets, an angular direction of the target in an x-plane, and an angular direction of the target in a y-plane.

10. A processing system according to claim 7, wherein said set of linear equations include:

11. A processing system according to claim 7, wherein said set of algebraic equations includes:

$T_{x,1}=\frac{\left(A-D\right)+\sqrt{{\left(A-D\right)}^2-4<br><br>E<br><br>\text{\hspace{1em}<br><br>}<br><br>B}}{2<br><br>B}$$T_{y,1}=\frac{B<br><br>\text{\hspace{1em}<br><br>}<br><br>T_{x,1}-A}{C}$$T_{x,2}=\frac{\left(A-D\right)-\sqrt{{\left(A-D\right)}^2-4<br><br>E<br><br>\text{\hspace{1em}<br><br>}<br><br>B}}{2<br><br>B}$$T_{y,2}=\frac{B<br><br>\text{\hspace{1em}<br><br>}<br><br>T_{x,2}-A}{C}$

where;

T_x,1, T_y,1, T_x,2, T_y,2 are the signals representing the angular directions of the targets; and

A, B, C, D, E and F comprise the set of intermediate values.

12. A processing system according to claim 8, wherein said further set of algebraic equations includes:

${\mathrm{\Sigma <br><br>}}_1=\frac{\sum <br><br>T_{x,2}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Delta <br><br>}}_{\mathrm{az}}}{T_{x,2}-T_{x,1}}$${\mathrm{\Sigma <br><br>}}_2=\frac{\sum <br><br>T_{x,1}+j<br><br>\text{\hspace{1em}<br><br>}<br><br>{\mathrm{\Delta <br><br>}}_{\mathrm{az}}}{T_{x,1}-T_{x,2}}$

where;

Σ

₁ and Σ

_z represent the amplitudes of the beam reflected respectively, from a first and from a second of the targets; and

T_x,1, T_y,1, T_x,2 and T_y,2 are the signals representing the angular directions of the targets.