Method to determine the azimuth of a target by means of a radar, especially of the ASR type

• US 6,680,687 B2
• Filed: 09/09/2002
• Issued: 01/20/2004
• Est. Priority Date: 09/07/2001
• Status: Expired due to Fees

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Phelipot, Michel
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): ALSOMIRI, ISAM A
• Application Number:
  US10/236,936
• Publication Number:
  US 20030052812A1
• Time in Patent Office: 498 Days
• Field of Search: 342/29,32,36,37,195,147,25
• US Class Current: 342/29
• CPC Class Codes: G01S 13/24 using frequency agility of carrier wave
• CPC Class Codes: G01S 13/42 Simultaneous measurement of distance and other co-ordinates indirect measurement G01S13/46
• CPC Class Codes: G01S 13/91 for traffic control G01S13/93 takes precedence

Abstract

A method to determine a target azimuth with a radar. The radar sends out a wave of N-pulse bursts. The method includes in one burst: splitting up a N-pulse burst into two half bursts, of a front burst and a rear burst; filtering the front and rear bursts to associate an azimuth value θ₁ and an amplitude value A₁ with the front burst, and an azimuth value θ₂ and an amplitude value A₂ with the rear burst; and obtaining the target azimuth Az at a value corresponding to a maximum of a Gaussian curve passing through points having components (θ₁, A₁) and (θ₂, A₂).

Claims

1. A method to determine an azimuth of a target with a radar that sends out a wave of N-pulse bursts, wherein the method comprises in one burst:

splitting up into two half bursts an N-pulse burst of said N-pulse bursts, of a front burst and a rear burst;

filtering the front and rear bursts to associate an azimuth value θ

₁ and an amplitude value A₁ with the front burst, and an azimuth value θ

₂ and an amplitude value A₂ with the rear burst; and

obtaining the azimuth Az of the target at a value corresponding to a maximum of a Gaussian curve passing through points having components (θ

₁, A₁) and (θ

₂, A₂).

2. A method according to claim 1, wherein the front and rear bursts each comprises N/2 impulsions.

3. A method according to claim 2, wherein the azimuth Az is given by the following relationship:

$\mathrm{Az}=\left(\frac{{\mathrm{\theta <br><br>}}_1+{\mathrm{\theta <br><br>}}_2}{2}\right)+\frac{{\mathrm{\theta <br><br>}}_{3<br><br>\mathrm{dB}}^2}{2<br><br>a<br><br>\left({\mathrm{\theta <br><br>}}_1-{\mathrm{\theta <br><br>}}_2\right)}<br><br>\mathrm{Log}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{A_1}{A_2}$

“

θ

_3dB”

being the width of the antenna lobe of the radar in azimuth, expressed at −

3 dB; and

“

a”

being a constant.

4. A method according to claim 2, wherein the burst contains only one piece of information.

5. A method according to claim 2, wherein the radar is of an ASR type.

6. A method according to claim 1, wherein the azimuth Az is given by the following relationship:

$\begin{array}{cc}\mathrm{Az}=\left(\frac{{\mathrm{\theta <br><br>}}_1+{\mathrm{\theta <br><br>}}_2}{2}\right)+\frac{{\mathrm{\theta <br><br>}}_{3<br><br>\mathrm{dB}}^2}{2<br><br>a<br><br>\left({\mathrm{\theta <br><br>}}_1-{\mathrm{\theta <br><br>}}_2\right)}<br><br>\mathrm{Log}<br><br>\text{\hspace{1em}<br><br>}<br><br>\frac{A_1}{A_2}& \left(1\right)\end{array}$

“

θ

_3dB”

being the width of the antenna lobe of the radar in azimuth, expressed at −

3 dB; and

“

a”

being a constant.

7. A method according to claim 6, wherein the burst contains only one piece of information.

8. A method according to claim 6, wherein the radar is of an ASR type.

9. A method according to claim 1, wherein the burst contains only one piece of information.

10. A method according to claim 9, wherein the radar is of an ASR type.

11. A method according to claim 1, wherein the radar is of an ASR type.