APPARATUS FOR ESTIMATING THE HEIGHT AT WHICH A TARGET FLIES OVER A REFLECTIVE SURFACE

• US 20100149021A1
• Filed: 12/15/2009
• Published: 06/17/2010
• Est. Priority Date: 12/17/2008
• Status: Active Grant

• Current Assignee: Thales Nederland BV (Thales SA)
• Original Assignee: Thales Nederland BV (Thales SA)
• Inventors: Driessen, Hans, Podt, Martin
• Granted Patent: US 8,659,470 B2
• Time in Patent Office: Days
• US Class Current: 342/118
• CPC Class Codes: G01S 13/4418 with means for eliminating radar-dependent errors in angle measurements, e.g. multipath effects
• CPC Class Codes: G01S 13/66 Radar-tracking systems; Analogous systems

Abstract

There is disclosed a method for estimating the height at which a target flies over a reflective surface.

The method comprises a step of emitting a signal and a step of receiving signals, including the emitted signal after it has been echoed by the target.

The method also comprises a step of filtering the received signals.

The method also comprises a step of modeling a direct signal, coming directly from the target after the emitted signal has been echoed by the target, and of modeling an indirect signal, coming indirectly from the target after the emitted signal has been echoed by the target and has been reflected by the surface, based on reflection parameters including the amplitude of the reflection coefficient of the surface and/or the phase difference between the direct signal and the indirect signal.

The step of filtering estimates dynamically the reflection parameters by use of a particle filter or a Gaussian-Sum filter.

Claims

1. An apparatus for estimating the height (h_t) at which a target (T) flies over a reflective surface (S), the apparatus comprising:

means for emitting a signal;

means for receiving signals, including the emitted signal after it has been echoed by the target;

means for filtering the received signals;

means for modeling;

a direct signal (1) coming directly from the target (T) after the emitted signal has been echoed by the target (T);

an indirect signal (2) coming indirectly from the target (T) after the emitted signal has been echoed by the target (T) and has been reflected by the surface (S), based on reflection parameters including the amplitude of the reflection coefficient of the surface (S) and/or the phase difference between the direct signal (1) and the indirect signal (2);

the apparatus being characterized in that the means for filtering comprise a particle filter or a Gaussian-Sum filter for estimating dynamically the reflection parameters.

2. An apparatus according to claim 1, wherein the means for modeling implement a specular reflection model.

3. An apparatus according to claim 1, wherein the emitted signal is emitted at a constant frequency.

4. A method for estimating the height (h_t) at which a target (T) flies over a reflective surface (S), the method comprising:

a step of emitting a signal;

a step of receiving signals, including the emitted signal after it has been echoed by the target;

a step of filtering the received signals;

a step of modeling;

a direct signal (1) coming directly from the target (T) after the emitted signal has been echoed by the target (T);

an indirect signal (2) coming indirectly from the target (T) after the emitted signal has been echoed by the target (T) and has been reflected by the surface (S), based on reflection parameters including the amplitude of the reflection coefficient of the surface (S) and/or the phase difference between the direct signal (1) and the indirect signal (2);

the method being characterized in that the step of filtering estimates dynamically the reflection parameters by use of a particle filter or a Gaussian-Sum filter.

5. A method according to claim 4, wherein the step of modeling uses a specular reflection model.

6. A method according to claim 4, wherein the emitted signal is emitted at a constant frequency.