METHOD AND SYSTEM FOR DETECTING GROUND OBSTACLES FROM AN AIRBORNE PLATFORM

• US 20110133979A1
• Filed: 11/03/2010
• Published: 06/09/2011
• Est. Priority Date: 11/04/2009
• Status: Active Grant

• Current Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno, Rockwell Collins France
• Original Assignee: Nederlandse Organisatie Voor Toegepast-Natuurwetenschappelijk Onderzoek Tno, Rockwell Collins France
• Inventors: Elferink, Franciscus Hendrikus, Van Dijk, Sebastiaan Gerardus Maria, Otten, Maternus Petrus Gerardus, Itcia, Eric, Mazuel, Sébastien, Huizing, Albert Gezinus
• Granted Patent: US 8,519,882 B2
• Time in Patent Office: Days
• US Class Current: 342/29
• CPC Class Codes: G01S 13/536 using transmission of continuous unmodulated waves, amplitude-, frequency-, or phase-modulated waves
• CPC Class Codes: G01S 2013/0263 Passive array antenna
• CPC Class Codes: G01S 7/414 Discriminating targets with respect to background clutter

Abstract

This method for detecting ground obstacles from an airborne platform comprises:

• • a step of illuminating the whole field of view of interest with an electromagnetic wave in the range of 0.1 to 100 GHz;
  • a step of receiving the echoes with multiple antenna elements from the whole field of interest and of transforming said echoes into a digital signal per antenna element;
  • a step of combining said digital signals simultaneously in order to obtain simultaneously multiple beams;
  • a step of Range and Velocity filtering each beam in parallel;
  • a step of applying on each filtered beam a detection process using a threshold on amplitude to detect potential ground obstacles; and
  • a step of discriminating said ground obstacles from said potential ground obstacles due to their specific signature in terms of both relative velocity and distance using velocity of the airborne platform.

Claims

1. A method for detecting ground obstacles from an airborne platform comprising:

a step of illuminating the whole field of view of interest with an electromagnetic wave in the range of 0.1 to 100 GHz;

a step of receiving the echoes with multiple antenna elements from the whole field of interest and of transforming said echoes into a digital signal per antenna element;

a step of combining said digital signals simultaneously in order to obtain simultaneously multiple beams covering the whole field of interest using spatial transformation processing;

a step of Range and Velocity filtering each beam in parallel;

said method further comprising;

a step of applying on each filtered beam a detection process using a threshold on amplitude to detect potential ground obstacles; and

a step of discriminating said ground obstacles from said potential ground obstacles due to their specific signature in terms of both relative velocity and distance using velocity of the airborne platform.

2. A detection method according to claim 1, wherein said step of discriminating is further based on the evolution of said signature.

3. A detection method according to claim 1, wherein said step of discriminating also uses altitude of the airborne platform.

4. A detection method according to claim 1, wherein said Range and Velocity filtering step comprises a range migration compensation process using said velocity and altitude of said airborne platform.

5. A detection method according to claim 1, further comprising a step of applying a spatial time adaptive filtering implemented by forming a specific beam directed to an assumed obstacle and optimizing the signal to ground clutter plus noise ratio, said filtering comprising

calculating a covariance matrix for at least two beams formed simultaneously of same azimuth;

optimizing a signal to ground-noise ratio in a given direction by forming a weight vector using said matrix and a steering vector in said direction;

applying said weight vector to said beams and summing channels to form a specific beam directed to the assumed obstacle which optimizes the signal to clutter plus noise ratio.

6. A detection method according to claim 1, wherein said threshold is an adaptive threshold determined using at least the velocity or the altitude of the airborne platform.

7. A detection method according to claim 1, wherein said detection process uses a CFAR technique in which ground clutter plus noise is estimated using a priori ground clutter knowledge.

8. A detection method according to claim 7, wherein said noise is estimated at constant Velocity using a Gaussian windowing.

9. A detection method according to claim 1, wherein said electromagnetic wave is characterized by a Frequency Modulated Continuous Wave form.

10. A detection method according of claim 1, wherein said wave frequency is between 9 to 18 GHz.

12. A computer program including instructions for executing the steps of a detection method according to any one of claims 1 to 10 when said program is executed by a computer.

13. A computer-readable storage medium storing a computer program including instructions for executing the steps of a detection method according to any one of claims 1 to 10.

11. A detecting system for detecting ground obstacles from an airborne platform comprising:

a transmit antenna for illuminating the whole field of view of interest with an electromagnetic wave in the range of 0.1 to 100 GHz

multiple antenna elements for receiving the echoes from the whole field of interest and means for transforming said echoes into a digital signal per antenna element;

means for combining said digital signals simultaneously in order to obtain simultaneously multiple beams covering the whole field of interest using spatial transformation processing;

filtering means for Range and Velocity filtering each beam in parallel;

Wherein said detection system comprises;

detection means for applying on each filtered beam a detection process using a threshold on amplitude to detect potential ground obstacles; and

discriminating means for discriminating said ground obstacles from said potential ground obstacles due to their specific signature in terms of both relative velocity and distance using velocity of the airborne platform.