Airborne systems and detection methods localization and production of images of buried objects and characterization of the composition of the subsurface

Airborne system for detection, location and imaging of buried objects, comprising:

• a transmitter aerial module, which comprises a first radar unit that emits radar signals, a positioning and guidance system of the transmitter aerial module, and an air control unit which collets information from the radar unit and from the positioning and guidance system, controls flight parameters of the transmitter aerial module and exchanges information with a ground station;
• a receiver aerial module, which comprises a second radar unit that captures the radar signal, a positioning and guidance system of the receiver aerial module, and an air control unit which collects information from the second radar unit and positioning and guidance system, controls flight parameters of the receiver aerial module and exchanges information with a ground station;
• a ground station which comprises a flight control system of the transmitter aerial module and of the receiver aerial module, a radar signal processing unit that processes the radar signals received from the second radar unit by means of a set of radar signal processing algorithms, and a computer application for the representation of the radar image of the subsoil obtained from the radar signal processing unit;
• and
• communication means for transmitting and receiving wireless signals between the transmitter aerial module and the ground station, between the receiver aerial module and the ground station, and between the transmitter aerial module and the receiver aerial module;
• wherein the positioning and guidance system of the transmitter aerial module and of the receiver aerial module each comprises a global positioning system, a positioning system based on inertial sensors, a positioning system based on real-time satellite kinetic navigation exchanging information with a real-time satellite kinetic navigation base and station located at the ground station, and a photogrammetry-based positioning system, which send information to the air control unit providing the accurate three-dimensional location of the transmitter aerial module and the receiver aerial module and the georeference of the data obtained with the second radar unit with an accuracy equal to or less than three centimeters, and wherein a radar signal processing algorithm of the radar signal processing unit includes
• a SAR processing algorithm for obtaining the radar image wherein said SAR processing algorithm uses polarimetric information based on the measurement of the radar signal corresponding to two orthogonal polarizations of the scattered electric field;
• an algorithm for the characterization of the composition of the subsoil which carries out the estimation of the permittivity of the subsoil from the determination of the distance between the echo in the soil and the echo in a metallic calibration object, both observable in the radar image;
• and a clutter elimination algorithm of the radar image.

Method for detecting, locating and obtaining images of buried objects by

• a system wherein airborne means for emitting and capturing radar signals are in wireless communication with a ground station;
• said means for emitting and capturing radar signals optionally being contained in a single module;
• and
• said ground station comprising a flight control system, a radar signal processing unit that processes the radar signals received a radar unit by means of a set of radar signal processing algorithms, and a computer application for the representation of the radar image of the subsoil obtained from the radar signal processing unit;
• wherein a positioning and guidance system of the means for emitting and capturing radar signals comprises a global positioning system, a positioning system based on inertial sensors, a positioning system based on real-time satellite kinetic navigation exchanging information with a real-time satellite kinetic navigation base station located at the ground station, and a photogramrnetry-based positioning system, which send information to the control unit providing the accurate three-dimensional location of the means for emitting and capturing radar signals and the georeference of the data obtained with the radar unit with an accuracy equal to or less than three centimeters, and characterized in that a radar signal processing algorithm of the radar signal processing unit includes
• a SAP, processing algorithm for obtaining the radar image wherein said SAR processing algorithm uses polarimetric information based on the measurement of the radar signal corresponding to two orthogonal polarizations of the scattered electric field;
• an algorithm for the characterization of the composition of the subsoil which carries out the estimation of the permittivity of the subsoil from the determination of the distance between the echo in the soil and the echo in a metallic calibration object, both observable in the radar image;
• and
• a clutter elimination algorithm of the radar image,
• said method comprising the following steps:
• a) emit a radar signal generated by a radar unit towards the soil to be inspected;
• b) capture the radar signal reflected in the soil, subsoil and possible buried objects, through a radar unit and determine the accurate three-dimensional location of the air module with equal value accuracy or less than three centimeters;
• c) send the radar signal and the accurate three-dimensional location of the air module to the ground station using the communication system;
• d) process the radar signal in the radar signal processing unit to obtain a three-dimensional image of the subsoil and detect and locate possible buried objects by means of a set of radar signal processing algorithms comprising a SAR processing algorithm for obtaining the radar image and a clutter elimination algorithm for the radar image.

Method for characterizing the composition of the subsoil by:

• a system wherein airborne means for emitting and capturing radar signals are in communication with a ground station;
• said means for emitting and capturing radar signals optionally being contained in a single module;
• said ground station comprising a flight control system, a radar signal processing unit that processes the radar signals received from a radar unit by means of a set of radar signal processing algorithms, and a computer application for the representation of a radar image of the subsoil obtained from the radar signal processing unit wherein a positioning and guidance system of the means for emitting and capturing radar signals comprises a global positioning system, a positioning system based on inertial sensors, a positioning system based on real-time satellite kinetic navigation exchanging information with a real-time satellite kinetic navigation base station located at the ground station, and a photogrammetry-based positioning system, which send information to the control unit providing the accurate three-dimensional location of the means for emitting and capturing radar signals and the georeference of the data obtained with the radar unit with an accuracy equal to or less than three centimeters, and wherein a radar signal processing algorithm of the radar signal processing unit is a SAR processing algorithm for obtaining the radar image and another is a clutter elimination algorithm of the radar image system wherein airborne means for emitting and capturing radar signals are in wireless communication with a ground station which comprises a flight control system, a radar signal processing unit that processes the radar signals received from the radar unit by means of a set of radar signal processing algorithms, and a computer application for the representation of the radar image of the subsoil obtained from the radar signal processing unit wherein a positioning and guidance system of the means for emitting and capturing radar signals comprises a global positioning system, a positioning system based on inertial sensors, a positioning system based on real-time satellite kinetic navigation exchanging information with a real-time satellite kinetic navigation base station located at the ground station, and a photogrammetry-based positioning system, which send information to the control unit providing the accurate three-dimensional location of the means for emitting and capturing radar signals and the georeference of the data obtained with the radar unit with an accuracy equal to or less than three centimeters, and characterized in that a radar signal processing algorithm of the radar signal processing unit includes
• a SAR processing algorithm for obtaining the radar image wherein said SAR processing algorithm uses polarimetric information based on the measurement of the radar signal corresponding to two orthogonal polarizations of the scattered electric field;
• an algorithm for the characterization of the composition of the subsoil which carries out the estimation of the permittivity of the subsoil from the determination of the distance between the echo in the soil and the echo in a metallic calibration object, both observable in the radar image;
• and
• a clutter elimination algorithm of the radar image said method comprising the following steps:
• a) bury a metallic calibration object in the subsoil;
• b) emit a radar signal generated by a radar unit towards the soil where the metallic calibration object is buried;
• c) capture the radar signal reflected in the soil, subsoil and in the metallic calibration object, through a radar unit and determining the three-dimensional location of the air module with an accuracy of equal to or less than three centimeters;
• d) send the radar signal and the accurate three-dimensional location of the air module to the ground station using a communication system;
• e) process the radar signal a radar signal processing unit to characterize the composition of the subsoil by means of an algorithm for the characterization of the composition of the subsoil in which the echo in the soil and the echo in a metallic calibration object are considered.