2021 18th European Radar Conference (EuRAD), Apr 5, 2022
Many filtering strategies can be applied to estimate target position along the range profile in o... more Many filtering strategies can be applied to estimate target position along the range profile in orthogonal frequency-division multiplexing radar. Chief among these filters are the matched filter (MF) and the zero forcing (ZF) method. For each technique, this paper compares the impact on the peak to side lobe ratio (PSLR) and the integrated side lobe ratio (ISLR). The results show that ZF scores higher than MF with respect to PSLR and ISLR in low-noise environments.
HAL (Le Centre pour la Communication Scientifique Directe), Jan 28, 2013
The objective of this study is to analyze scattering mechanisms using multi-incidence angle obser... more The objective of this study is to analyze scattering mechanisms using multi-incidence angle observations over agricultural fields. Radarsat-2 datasets acquired in the end of March / beginning of April with four different ranges of incidence angle are explored using polarimetric decomposition methodology. The results show that single scattering is always the dominant scattering mechanism over test sites, although single scattering occurs on bare surface is significantly stronger than that occurs in vegetation canopy. As incidence angle increases, single scattering decreases, and volumetric scattering increase as expected. Therefore, lower incidence angle acquisition is appropriate to characterize soil moisture over bare surface due to the limited effect of roughness, while higher incidence angle is suitable for surface roughness identification over bare surface and plant height description over vegetation canopy. Nevertheless, as the incidence angle increases towards 40 • , a saturation occurs which limits the application of images acquired using incidence angle bigger than 40 • to discriminate scattering mechanism. The potential of polarimetric differences ∆σ HH in dB, as well as ∆pr to characterize wheat height is also demonstrated. The combination of various incidence angles helps us to monitor crop growth cycle and also to get a better estimation of soil parameters.
Cette communication décrit la réalisation d'un projet étudiant (projet Air'o) destiné au suivi de... more Cette communication décrit la réalisation d'un projet étudiant (projet Air'o) destiné au suivi de la pollution de l'air en collaboration avec l'association Air Breizh. Ce projet a été initié pendant l'année universitaire 2019-2020 lors de la 2 ème année ingénieur (niveau M1) au sein du département « électronique et télécommunications » de l'INSA de Rennes. Le but du projet est de proposer une mesure de la qualité de l'air par l'intermédiaire de capteurs embarqués sur des vélos. Une transmission de la position du capteur ainsi que la mesure de pollution en temps réel via le réseau LoRaWAN (Long Range Wide-area Network) permet de localiser les niveaux de pollution tout au long du parcours du vélo. Ce suivi de la qualité de l'air s'effectue par la récupération des données (pollution, position) sur un serveur dédié. Une application spécifique est développée afin de situer géographiquement les niveaux de pollution enregistrés. La réalisation d'un prototype est présentée ainsi que la transmission des informations. Des premiers résultats indiquent la pertinence du concept développé.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 8, 2022
-De nombreuses techniques de focalisation sont utilisées pour établir la réponse en distance avec... more -De nombreuses techniques de focalisation sont utilisées pour établir la réponse en distance avec un radar OFDM (Orthogonal Frequency Division Multiplex). Les plus connues parmi elles sont le filtre adapté (ou matched filter, MF) et le forçage à zéro (ou zero forcing, ZF). Cet article compare les grandeurs de PSLR (Peak Side Lobe Ratio) et ISLR (Integrated Side Lobe Ratio) de chacune de ces deux techniques. Les résultats montrent un avantage pour la technique ZF par rapport à la technique MF dans des environnements peu bruités.
IEEE Geoscience and Remote Sensing Letters, Feb 1, 2014
This letter presents the use of polynomial Wigner-Ville distribution (PWVD) for accurate velocity... more This letter presents the use of polynomial Wigner-Ville distribution (PWVD) for accurate velocity estimation as used in remote road traffic management applications. In such applications based on inverse synthetic aperture radar, velocity estimation is central to obtain a suitable level of performance of the signal processing. Moreover, the precision of this velocity estimation is crucial in order to achieve the best detection and estimation of the gauge of the vehicles through the use of radar images. Hence, the PWVD is applied as an instantaneous frequency estimator used in this traffic surveillance application.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 3, 2014
The objective of this study is to evaluate the surface roughness and soil moisture effects on pol... more The objective of this study is to evaluate the surface roughness and soil moisture effects on polarimetric parameters under multi-incidence angle condition. In order to achieve this objective, we propose to use Ground Based (GB) SAR experiments, in which the specific levels of surface roughness and soil moisture are set deliberately. The results show that image acquired with high incidence angle is more sensitive to surface roughness than that with low incidence angle. Moreover, the results we obtained with our GB-SAR system (called PoSAR for Pocket SAR) are in agreement with the behavior of multi-angular RADARSAT-2 data that we have previously obtained. This indicates that the combination of various incidence angles may help us to improve surface roughness monitoring accuracy and also to get a better estimation of soil parameters.
IEEE Transactions on Geoscience and Remote Sensing, 2022
In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of... more In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of two covariance matrices for unsupervised change detection in polarimetric radar images. The multilook complex covariance matrix is assumed to follow a scaled complex Wishart distribution. In doing so, we provide the distribution of the DRT statistic that is exactly Wilks's lambda of the second kind distribution, with density expressed in terms of Meijer G-functions. Due to this distribution, the constant false alarm rate (CFAR) algorithm is derived in order to achieve the required performance. More specifically, a threshold is provided by the CFAR to apply to the DRT statistic producing a binary change map. Finally, simulated and real multilook polarimetric SAR (PolSAR) data are employed to assess the performance of the method and is compared with the Hotelling-Lawley trace (HLT) statistic and the likelihood ratio test (LRT) statistic.
2021 18th European Radar Conference (EuRAD), Apr 5, 2022
Many filtering strategies can be applied to estimate target position along the range profile in o... more Many filtering strategies can be applied to estimate target position along the range profile in orthogonal frequency-division multiplexing radar. Chief among these filters are the matched filter (MF) and the zero forcing (ZF) method. For each technique, this paper compares the impact on the peak to side lobe ratio (PSLR) and the integrated side lobe ratio (ISLR). The results show that ZF scores higher than MF with respect to PSLR and ISLR in low-noise environments.
HAL (Le Centre pour la Communication Scientifique Directe), Jan 28, 2013
The objective of this study is to analyze scattering mechanisms using multi-incidence angle obser... more The objective of this study is to analyze scattering mechanisms using multi-incidence angle observations over agricultural fields. Radarsat-2 datasets acquired in the end of March / beginning of April with four different ranges of incidence angle are explored using polarimetric decomposition methodology. The results show that single scattering is always the dominant scattering mechanism over test sites, although single scattering occurs on bare surface is significantly stronger than that occurs in vegetation canopy. As incidence angle increases, single scattering decreases, and volumetric scattering increase as expected. Therefore, lower incidence angle acquisition is appropriate to characterize soil moisture over bare surface due to the limited effect of roughness, while higher incidence angle is suitable for surface roughness identification over bare surface and plant height description over vegetation canopy. Nevertheless, as the incidence angle increases towards 40 • , a saturation occurs which limits the application of images acquired using incidence angle bigger than 40 • to discriminate scattering mechanism. The potential of polarimetric differences ∆σ HH in dB, as well as ∆pr to characterize wheat height is also demonstrated. The combination of various incidence angles helps us to monitor crop growth cycle and also to get a better estimation of soil parameters.
Cette communication décrit la réalisation d'un projet étudiant (projet Air'o) destiné au suivi de... more Cette communication décrit la réalisation d'un projet étudiant (projet Air'o) destiné au suivi de la pollution de l'air en collaboration avec l'association Air Breizh. Ce projet a été initié pendant l'année universitaire 2019-2020 lors de la 2 ème année ingénieur (niveau M1) au sein du département « électronique et télécommunications » de l'INSA de Rennes. Le but du projet est de proposer une mesure de la qualité de l'air par l'intermédiaire de capteurs embarqués sur des vélos. Une transmission de la position du capteur ainsi que la mesure de pollution en temps réel via le réseau LoRaWAN (Long Range Wide-area Network) permet de localiser les niveaux de pollution tout au long du parcours du vélo. Ce suivi de la qualité de l'air s'effectue par la récupération des données (pollution, position) sur un serveur dédié. Une application spécifique est développée afin de situer géographiquement les niveaux de pollution enregistrés. La réalisation d'un prototype est présentée ainsi que la transmission des informations. Des premiers résultats indiquent la pertinence du concept développé.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 8, 2022
-De nombreuses techniques de focalisation sont utilisées pour établir la réponse en distance avec... more -De nombreuses techniques de focalisation sont utilisées pour établir la réponse en distance avec un radar OFDM (Orthogonal Frequency Division Multiplex). Les plus connues parmi elles sont le filtre adapté (ou matched filter, MF) et le forçage à zéro (ou zero forcing, ZF). Cet article compare les grandeurs de PSLR (Peak Side Lobe Ratio) et ISLR (Integrated Side Lobe Ratio) de chacune de ces deux techniques. Les résultats montrent un avantage pour la technique ZF par rapport à la technique MF dans des environnements peu bruités.
IEEE Geoscience and Remote Sensing Letters, Feb 1, 2014
This letter presents the use of polynomial Wigner-Ville distribution (PWVD) for accurate velocity... more This letter presents the use of polynomial Wigner-Ville distribution (PWVD) for accurate velocity estimation as used in remote road traffic management applications. In such applications based on inverse synthetic aperture radar, velocity estimation is central to obtain a suitable level of performance of the signal processing. Moreover, the precision of this velocity estimation is crucial in order to achieve the best detection and estimation of the gauge of the vehicles through the use of radar images. Hence, the PWVD is applied as an instantaneous frequency estimator used in this traffic surveillance application.
HAL (Le Centre pour la Communication Scientifique Directe), Jun 3, 2014
The objective of this study is to evaluate the surface roughness and soil moisture effects on pol... more The objective of this study is to evaluate the surface roughness and soil moisture effects on polarimetric parameters under multi-incidence angle condition. In order to achieve this objective, we propose to use Ground Based (GB) SAR experiments, in which the specific levels of surface roughness and soil moisture are set deliberately. The results show that image acquired with high incidence angle is more sensitive to surface roughness than that with low incidence angle. Moreover, the results we obtained with our GB-SAR system (called PoSAR for Pocket SAR) are in agreement with the behavior of multi-angular RADARSAT-2 data that we have previously obtained. This indicates that the combination of various incidence angles may help us to improve surface roughness monitoring accuracy and also to get a better estimation of soil parameters.
IEEE Transactions on Geoscience and Remote Sensing, 2022
In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of... more In this article, we propose a determinant ratio test (DRT) statistic to measure the similarity of two covariance matrices for unsupervised change detection in polarimetric radar images. The multilook complex covariance matrix is assumed to follow a scaled complex Wishart distribution. In doing so, we provide the distribution of the DRT statistic that is exactly Wilks's lambda of the second kind distribution, with density expressed in terms of Meijer G-functions. Due to this distribution, the constant false alarm rate (CFAR) algorithm is derived in order to achieve the required performance. More specifically, a threshold is provided by the CFAR to apply to the DRT statistic producing a binary change map. Finally, simulated and real multilook polarimetric SAR (PolSAR) data are employed to assess the performance of the method and is compared with the Hotelling-Lawley trace (HLT) statistic and the likelihood ratio test (LRT) statistic.
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Papers by Stéphane Méric