Development and implementation of a very high resolution tomographic ground radar for the characterization of complex volumes

Ce travail de thèse concerne le développement et la mise en oeuvre d’un nouveau système radar MIMO-OFDM portable, léger, peu complexe et peu coûteux, capable de mesurer et de caractériser un volume complexe 3-D comme un manteau neigeux, une forêt. Une technique MIMO, qui étend le principe de l’OFDM à des éléments antennaires d’un réseau est proposée afin d’éviter l’utilisation de commutateurs lors de l’émission et la réception des signaux. Le système fonctionne en bande C et mesure des environnements volumiques en champ proche et à haute résolution (5 cm en distance et 15 cm en élévation). Il est destiné à la caractérisation de manteaux neigeux stratifiés présentant une homogénéité dans la direction horizontale et une épaisseur inférieure à quatre mètres. Le radar possède un système autonome de génération et d’acquisition de signaux. Un processus d’imagerie 3-D par focalisation de signaux à large bande a été développé et appliqué sur des mesures réalisées en janvier et mars 2019, puis mars 2020 dans les Alpes françaises. Divers paramètres physiques, dont le profil diélectrique d’un couvert, la structure de sa réponse EM 3D ont été estimés, qui pourront être utilisés pour interpréter des résultats de mesures SAR 2-D satellitaires opérées dans la même bande.This doctoral work concerns the development and implementation of a new portable, lightweight, low-cost and low complexity radar system, able to monitor and characterize a complex 3-D volume such as a snow pack, a forest. A MIMO technique that extends the OFDM principle to elements of an antenna array is proposed in order to avoid the use of switches when transmitting and receiving signals. The system operates at C band and measures volumetric environments in near field and at high resolution (5 cm in ground range and 15 cm in elevation). It is dedicated to the characterization of stratified snow packs having depth of up to four meters and a homogeneous structure in the horizontal direction. The radar autonomously generates and acquires signals . A 3-D imaging process, based on the focusing of wide band signals has been developed and applied to measurements performed January and march 2019 and in march 2020 in the French Alps. Several physical features, including the dielectric profile of a snow cover, and the structure of its 3D EM responses have been estimated, and could be used to analyze 2-D space borne SAR images acquired in the same frequency band

Phase Noise Influence on Radar Signal Focusing and SAR Tomography

International audienceThis paper studies the influence of phase noise (PN) on radar signal focusing and SAR tomography. Firstly, we create and add PN to simulated data for 1D focusing. A quasi-linear degradation of resolution is observed for 1 kHz PN level higher than -22 dBc/Hz. Secondly, PN is added to multi channel measured data showing that I kHz PN level higher than -60 dBc/Hz affects SAR tomographic reconstruction quality

Portable wide-band MIMO tomographic radar system for in situ high-resolution 3-D imaging at C band

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Système Radar MIMO en Bande C Pour la Caractérisation à Haute Résolution de Volumes Complexes

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Low Complexity Portable MIMO Radar System for the Characterization of Complex Environments at High Resolution

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3D SAR imaging using bistatic opposite side acquisitions, the bizona concept

International audienceThis paper proposes a new three dimensional imaging mode, called Bizona, based on acquisitions performed in a forward-looking bistatic configuration,. It is shown that spatial diversity using several transmitting, or receiving, positions permit to overcome some ambiguities and lack of sensitivity in the horizontal direction of such geometrical configurations, and that the Bizona mode is characterized by a higher power budget and a natural ability to discriminate scatterers located at different heights. The performance of this imaging principle is assessed using both simulated and measured signal

Mosideo/cirfa tank experiments on behavior and detection of oil in ice

In the Arctic, presence of sea ice presents a challenge to safe and sustainable operations. To optimize planning and minimize impact of inadvertent oil spills, oil-in-ice experiments were performed at the HSVA Arctic Environmental Test Basin (AETB) from 14 March to 4 April 2017. Following an under-ice spill and simulated springtime warming, the microscopic movement and distribution of oil in the sea ice pore space as well as the detectability of oil as it approaches the surface were investigated. Two ice types were studied simultaneously, i.e., columnar ice with and without a granular ice surface layer. Among the detection techniques were electromagnetic (radar, tomographic SAR) and optical (fluorescent, hyperspectral, thermal) sensors, and microscopic distribution of oil in sea ice were determined through X-ray computed tomography (CT). This paper presents the setup of the experiment and general ice properties. It was found that the movement of oil differed considerably between the investigated ice types. Predicting the behavior of oil in ice based on environmental conditions will help optimize the approaches used in spill detection and response.publishedVersio

CHARACTERIZATION OF ALPINE SNOWPACKS USING A LOW COMPLEXITY PORTABLE MIMO RADAR SYSTEM

International audienceThis paper presents experimental results of the 3-D characterization of alpine snowpacks, obtained using a low complexity portable MIMO radar system that operates at C-band. Different types of snow at different altitudes and seasons are studied. The acquired datasets are processed using the Back Projection Algorithm and the resulting tomograms are compared to Meteo France ground measurements (Snow Micro Pen transects, density and stratigraphy profiles and liquid water content). The obtained tomograms show that the system mostly detects melt forms and faceted crystals. These measurements provide 3-D electromagnetic ground truth that can be used to confirm the results obtained by Sentinel-1

Mosideo/cirfa tank experiments on behavior and detection of oil in ice

In the Arctic, presence of sea ice presents a challenge to safe and sustainable operations. To optimize planning and minimize impact of inadvertent oil spills, oil-in-ice experiments were performed at the HSVA Arctic Environmental Test Basin (AETB) from 14 March to 4 April 2017. Following an under-ice spill and simulated springtime warming, the microscopic movement and distribution of oil in the sea ice pore space as well as the detectability of oil as it approaches the surface were investigated. Two ice types were studied simultaneously, i.e., columnar ice with and without a granular ice surface layer. Among the detection techniques were electromagnetic (radar, tomographic SAR) and optical (fluorescent, hyperspectral, thermal) sensors, and microscopic distribution of oil in sea ice were determined through X-ray computed tomography (CT). This paper presents the setup of the experiment and general ice properties. It was found that the movement of oil differed considerably between the investigated ice types. Predicting the behavior of oil in ice based on environmental conditions will help optimize the approaches used in spill detection and response

Mosideo/cirfa tank experiments on behavior and detection of oil in ice

In the Arctic, presence of sea ice presents a challenge to safe and sustainable operations. To optimize planning and minimize impact of inadvertent oil spills, oil-in-ice experiments were performed at the HSVA Arctic Environmental Test Basin (AETB) from 14 March to 4 April 2017. Following an under-ice spill and simulated springtime warming, the microscopic movement and distribution of oil in the sea ice pore space as well as the detectability of oil as it approaches the surface were investigated. Two ice types were studied simultaneously, i.e., columnar ice with and without a granular ice surface layer. Among the detection techniques were electromagnetic (radar, tomographic SAR) and optical (fluorescent, hyperspectral, thermal) sensors, and microscopic distribution of oil in sea ice were determined through X-ray computed tomography (CT). This paper presents the setup of the experiment and general ice properties. It was found that the movement of oil differed considerably between the investigated ice types. Predicting the behavior of oil in ice based on environmental conditions will help optimize the approaches used in spill detection and response