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  • Pràctiques de laboratori de Projecte Bàsic d'Enginyeria (ETSETB-UPC)

     Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Duffo Ubeda, Nuria; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2014-02-03
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  • Radiation and Propagation: Test on Linear Circuits (English)

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    Date: 2014-01-07
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  • RP: Autotest conocimientos previos Circuitos Lineales

     Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    Date: 2014-01-07
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  • La gran lluita contra el mar (història del cable trasatlàntic)

     Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Romeu Robert, Jordi
    Date: 2014-02-12
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  • Transitori en línies de transmissió ideal

     Fabregas Canovas, Francisco Javier; Torres Torres, Francisco
    Date: 2014-02-14
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  • Perturbation analysis of eigenvector-based target decomposition theorems in radar polarimetry

     López Martínez, Carlos; Alonso González, Alberto; Fabregas Canovas, Francisco Javier
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2014
    Journal article

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    A novel analysis of the statistics of the eigendecomposition of the coherency matrix and the H/A/a¯ parameters of polarimetric synthetic aperture radar data is addressed. The objective is to overcome previous approaches that prevented the extraction of information about the sample eigenvectors or restricted the analysis to simulated data. This paper considers a perturbation analysis of the eigendecomposition of the coherency matrix, making it possible to obtain analytical expressions for the sample eigenvalues and their means and variances, the sample mean entropy and anisotropy, the sample eigenvectors and the sample ai angles, as well as for the sample mean alpha angle a¯. All the parameters are shown to be estimated asymptotically non-biased with respect to the number of averaged samples. It is also demonstrated that the sample eigenvectors are more robust than the sample eigenvalues to the presence of speckle. Finally, a simple technique for the precise removal of the entropy bias is presented.

    A novel analysis of the statistics of the eigendecomposition of the coherency matrix and the H/A/a¯ parameters of polarimetric synthetic aperture radar data is addressed. The objective is to overcome previous approaches that prevented the extraction of information about the sample eigenvectors or restricted the analysis to simulated data. This paper considers a perturbation analysis of the eigendecomposition of the coherency matrix, making it possible to obtain analytical expressions for the sample eigenvalues and their means and variances, the sample mean entropy and anisotropy, the sample eigenvectors and the sample ai angles, as well as for the sample mean alpha angle a¯. All the parameters are shown to be estimated asymptotically non-biased with respect to the number of averaged samples. It is also demonstrated that the sample eigenvectors are more robust than the sample eigenvalues to the presence of speckle. Finally, a simple technique for the precise removal of the entropy bias is presented.

  • Phase quality optimization in polarimetric differential SAR interferometry

     Iglesias Gonzalez, Ruben; Monells Miralles, Daniel; Fabregas Canovas, Francisco Javier; Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; López Martínez, Carlos
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2014-05
    Journal article

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    In this paper, a study of polarimetric optimization techniques in the frame of differential synthetic aperture radar (SAR) interferometry (DInSAR) is considered. Historically, DInSAR techniques have been limited to the single-polarimetric case, mainly due to the unavailability of fully polarimetric data. Lately, the launch of satellites with polarimetric capabilities, such as the Advanced Land Observing Satellite (ALOS), RADARSAT-2, or TerraSAR-X, allowed merging polarimetric and interferometric techniques to improve the pixels' phase quality and, thus, the density and the reliability of the final DInSAR results. The relationship between the polarimetrically optimized coherence or amplitude dispersion maps and the final DInSAR results is carefully analyzed, using both orbital and ground-based SAR fully polarimetric data. DInSAR processing using polarimetric optimization techniques in the pixel selection process is compared with the classical single-polarimetric approach, achieving up to a threefold increase of the number of pixel candidates in the coherence case and up to a factor of seven in the amplitude dispersion case.

  • Radiación y propagación (RP): colección de problemas

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-09-02
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  • Radiation and Propagation (RP-2B). Exercises. October 2013

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-10-07
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  • RP: anàlisi de rendiment acadèmic i satisfacció 2012-13 Q2

     Torres Torres, Francisco; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    Date: 2013-07-08
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  • Radiació i propagació. Pràctiques de laboratori

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-07-03
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  • La carta de Smith (Radiació i Ones Guiades)

     Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Miranda Mendoza, Carlos
    Date: 2013-09-27
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  • Link-Budget: la missió Interestel·lar Voyager

     Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Romeu Robert, Jordi
    Date: 2013-12-10
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    ARBRES: Light-weight CW/FM SAR sensors for small UAVs  Open access

     Aguasca Sole, Alberto; Acevo Herrera, René; Broquetas Ibars, Antoni; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier
    Sensors
    Date of publication: 2013-03-06
    Journal article

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    This paper describes a pair of compact CW/FM airborne SAR systems for small UAV-based operation (wingspan of 3.5 m) for low-cost testing of innovative SAR concepts. Two different SAR instruments, using the C and X bands, have been developed in the context of the ARBRES project, each of them achieving a payload weight below 5 Kg and a volume of 13.5 dm3 (sensor and controller). Every system has a dual receiving channel which allows operation in interferometric or polarimetric modes. Planar printed array antennas are used in both sensors for easy system integration and better isolation between transmitter and receiver subsystems. First experimental tests on board a 3.2 m wingspan commercial radio-controlled aircraft are presented. The SAR images of a field close to an urban area have been focused using a back-projection algorithm. Using the dual channel capability, a single pass interferogram and Digital Elevation Model (DEM) has been obtained which agrees with the scene topography. A simple Motion Compensation (MoCo) module, based on the information from an Inertial+GPS unit, has been included to compensate platform motion errors with respect to the nominal straight trajectory.

  • Polarimetric temporal analysis of urban environments with a ground-based SAR

     Pipia, Luca; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; López Martínez, Carlos
    IEEE transactions on geoscience and remote sensing
    Date of publication: 2013-04
    Journal article

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    Revisiting time constitutes a key constraint for continuous monitoring activities based on space- and airborne synthetic aperture radar (SAR) acquisitions. Conversely, the employment of terrestrial platforms overcomes this limitation and makes it possible to perform time-continuous observations of small space-scale phenomena. New research lines of SAR dealing with the backscattering evolution of different types of scenarios become hence possible through the analysis of ground-based SAR (gbSAR) data collections. The Remote Sensing Laboratory of the Universitat Politècnica de Catalunya drove a one-year measurements campaign in the village of Sallent, northeastern Spain, using its X-Band gbSAR sensor. The field experiment aimed at studying the subsidence phenomenon induced by the salt mining activity carried out in this area during the past decades. In this paper, the polarimetric behavior of an urban environment is investigated at different time scales. After a brief description of the test site and the measurement campaign, the analysis is focused on the stability on man-made structures at different time scales. PolSAR data monthly acquired from June 2006 to July 2007 are employed to stress the presence of nonstationary backscattering processes within the urban scene and the effect they have on differential phase information. Then, a filtering procedure aiming at reducing backscattering randomness in one-day and long-term data collections is then put forward. The improvements provided by the proposed technique are assessed using a new polarimetric descriptor, the time entropy. In the end, the importance of preserving the interferometric phase information from nonstationary backscattering contaminations using fully polarimetric data is discussed.

    Revisiting time constitutes a key constraint for continuous monitoring activities based on space- and airborne synthetic aperture radar (SAR) acquisitions. Conversely, the employment of terrestrial platforms overcomes this limitation and makes it possible to perform time-continuous observations of small space-scale phenomena. New research lines of SAR dealing with the backscattering evolution of different types of scenarios become hence possible through the analysis of ground-based SAR (gbSAR) data collections. The Remote Sensing Laboratory of the Universitat Politècnica de Catalunya drove a one-year measurements campaign in the village of Sallent, northeastern Spain, using its X-Band gbSAR sensor. The field experiment aimed at studying the subsidence phenomenon induced by the salt mining activity carried out in this area during the past decades. In this paper, the polarimetric behavior of an urban environment is investigated at different time scales. After a brief description of the test site and the measurement campaign, the analysis is focused on the stability on man-made structures at different time scales. PolSAR data monthly acquired from June 2006 to July 2007 are employed to stress the presence of nonstationary backscattering processes within the urban scene and the effect they have on differential phase information. Then, a filtering procedure aiming at reducing backscattering randomness in one-day and long-term data collections is then put forward. The improvements provided by the proposed technique are assessed using a new polarimetric descriptor, the time entropy. In the end, the importance of preserving the interferometric phase information from nonstationary backscattering contaminations using fully polarimetric data is discussed

  • Radiació i propagació. Fulls de resposta laboratori

     Corbella Sanahuja, Ignasi; Fabregas Canovas, Francisco Javier; Torres Torres, Francisco; Vall-llossera Ferran, Mercedes Magdalena
    Date: 2013-07-09
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  • Study of the speckle noise effects over the eigen decomposition of polarimetric SAR data: a review

     López Martínez, Carlos; Alonso González, Alberto; Fabregas Canovas, Francisco Javier
    International Workshop on Science and Applications of SAR Polarimetry and Polarimetric Interferometry
    Presentation's date: 2013-01
    Presentation of work at congresses

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    This paper is focused on considering the effects of speckle noise on the eigen decomposition of the co- herency matrix. Based on a perturbation analysis of the matrix, it is possible to obtain an analytical expression for the mean value of the eigenvalues and the eigenvectors, as well as for the Entropy, the Anisotroopy and the dif- ferent a angles. The analytical expressions are compared against simulated polarimetric SAR data, demonstrating the correctness of the different expressions.

  • Phase quality optimisation techniques and limitations in polarimetric differential SAR interferometry

     Iglesias, Rubén; Monells Miralles, Daniel; Fabregas Canovas, Francisco Javier; Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; López Martínez, Carlos
    International Workshop on Science and Applications of SAR Polarimetry and Polarimetric Interferometry
    Presentation's date: 2013-01
    Presentation of work at congresses

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    In this paper, the application of polarimetric optimization techniques for Differential SAR Interferometry (DInSAR) applications is studied. The objective of the proposed techniques is to increase the number of temporal coherent scatterers, improving thus the robustness of the DInSAR algorithms exploiting the polarimetric capabilities of data. The relationship between optimum coherences or amplitude dispersion maps, depending on the pixels selection method used, and the final DInSAR results is analyzed, using both orbital and Ground-Based SAR fully-polarimetric data. Moreover, the main advantages and drawbacks of each optimization method will be analyzed, especially when polarimetric stability does not apply. With the optimization techniques presented up to a twofold increase of the pixel candidates in the coherence case and up to a factor of seven in the amplitude dispersion case may be reached.

  • SAR Multidimensional para la observación de la tierra: sistemas, procesado y aplicaciones

     Alonso Gonzalez, Alberto; Centolanza, Giuseppe; Monells Miralles, Daniel; López Martínez, Carlos; Mallorqui Franquet, Jordi Joan; Broquetas Ibars, Antoni; Fabregas Canovas, Francisco Javier; Makhoul Varona, Eduardo; Aguasca Sole, Alberto
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  • Landslide monitoring with spotlight TerraSAR-X DATA

     Iglesias González, Rubén; Monells Miralles, Daniel; Centolanza, Giuseppe; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2012-07
    Presentation of work at congresses

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    This paper aims to demonstrate that radar-based remote sensing techniques can be as effective as the conventional geotechnical ones for the detection and monitoring of well suited areas. Many of the high mountain landslides are vegetated areas that decorrelate faster at X-band. As in these scenarios the number of coherent scatterers is low and, in addition, the area of interest is usually small, the processing can be benefited of the usage of high-resolution data. This will maximize the chances of detecting persistent scatters coming from both natural targets and man-made structures. The high resolution Spotlight mode of TerraSAR-X is thus the perfect choice as it offers a fine resolution. On the other hand, its 11 days of revisit time and X-band carrier allows the monitoring of small variations in the landslide trend and deal with its variable dynamics.

  • A new approach for atmospheric phase screen compensation in ground-based SAR over areas with steep topography

     Fabregas Canovas, Francisco Javier; Iglesias, Rubén; Aguasca Sole, Alberto
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2012-04
    Presentation of work at congresses

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  • Polarimetric optimization for DInSAR pixel selection with ground-based SAR

     Iglesias, Rubén; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; López Martínez, Carlos; Alonso Gonzalez, Alberto; Mallorqui Franquet, Jordi Joan
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2012-07
    Presentation of work at congresses

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  • Advanced polarimetric optimization for DInSAR applications with Ground-Based SAR

     Iglesias, Rubén; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; López Martínez, Carlos; Alonso Gonzalez, Alberto
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2012-04
    Presentation of work at congresses

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    In this paper, the applications of advanced polarimetric optimization techniques for Differential Interferometric SAR (DInSAR) pixel selection are explored in the framework of deformation map retrieval in landslides. Unfortunately, most of high mountain landslides occur on vegetated areas with a poor density of coherent scatterers that with a fast decorrelation at X-band. The objective of the techniques proposed in this paper is to increase the number of pixels with good quality, and thus the robustness of DInSAR algorithms, by exploiting the larger density of coherent scatterers present in polarimetric SAR data. Using Ground-Based SAR zero-baseline fullypolarimetric data sets, the relationship between optimum coherences and its corresponding phase in terms of DInSAR application is carefully analyzed. In the paper, different coherence optimization methods available in the literature are studied. The main advantages and drawbacks of the different approaches are drawn.

  • Application of high resolution spotlight TerraSAR-X data to landslide monitoring

     Iglesias, Rubén; Monells Miralles, Daniel; Centolanza, Giuseppe; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; López Martínez, Carlos
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2012-04
    Presentation of work at congresses

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    This paper seeks to demonstrate that radar-based remote sensing techniques, especially those based on orbital sensors, can be as effective as the conventional geotechnical and discrete GPS measurement ones for the detection and monitoring of well suited landslides. Unfortunately, deformation can only be retrieved for those landslides presenting a good orientation with respect the satellite orbit. In addition, many of the high mountain landslides are vegetated areas that decorrelate faster at X-band. As in these scenarios the number of persistent scatterers can be low and, at the same time, the area of interest is usually small, the processing can be benefited of the usage of high-resolution data that will maximize the chances of detecting persistent scatters coming from both natural targets and man-made structures. The high resolution Spotlight mode of TerraSAR-X is thus the perfect choice as it offers a fine resolution. In addition, its 11 days of revisit time and X-band carrier allows the monitoring of small variations in the landslide trend and deal with its variable dynamics. The landslide of study is ‘El Forn de Canillo’ (Andorra) where the deformation results will be compared and validated with those obtained with the deployed UPC’s Ground-Based (GB-SAR) X-band sensor.

  • Phase quality optimization in Orbital Differential SAR Interferometry with fully polarimetric data

     Monells Miralles, Daniel; Iglesias, Ruben; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier; López Martínez, Carlos
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2012-07
    Presentation of work at congresses

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    Orbital Differential SAR Interferometry (DInSAR) is a well-known technique to retrieve terrain deformation phenomena from wide areas with high resolution. Historically its application has been limited to single polarization SAR, mainly due to the unavailability of polarimetric data. Lately, the launch of several satellites with polarimetric capabilities, such as Radarsat-2 or TerraSAR-X, allows merging polarimetric and interferometric techniques in order to improve the results obtained in the DInSAR processing. This work will explore the existent analytical techniques in order to optimize the quality of the subsidence results. The dataset used contains 35 Fine Quad-Pol Radarsat-2 acquisitions over the city of Barcelona (Spain).

  • Analysis of speckle noise effects in polarimetric SAR interferometry

     López Martínez, Carlos; Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2012-07
    Presentation of work at congresses

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  • Analysis and validity of the polInSAR line model on forested areas

     López Martínez, Carlos; Fabregas Canovas, Francisco Javier; Alonso Gonzalez, Alberto
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2012-04
    Presentation of work at congresses

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    This paper focuses on the analysis of certain hypotheses considered in quantitative remote sensing of forest areas by means of Polarimetric SAR Interferometry (PolInSAR). When addressing the quantitative estimation of forest parameters in PolInSAR, the estimation is usually based on the inversion of the Random Volume over Ground (RVoG) coherent scattering model. We present an study of the validity of this assumption, based on the analysis of the measured data and the coherence region resulting from the variation of the interferometric coherence as a function of polarization.

  • Forest parameter estimation in the Pol-InSAR context employing the multiplicative¿additive speckle noise model

     López Martínez, Carlos; Fabregas Canovas, Francisco Javier; Pipia, Luca
    ISPRS journal of photogrammetry and remote sensing
    Date of publication: 2011-09
    Journal article

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    This paper addresses the problem of speckle noise on single baseline polarimetric SAR interferometry (Pol-InSAR) on the basis of the multiplicative–additive speckle noise model. Considering this speckle noise model, a novel filtering technique is defined and studied in terms of simulated and experimental Pol-InSAR data. As demonstrated, the use of the multiplicative–additive speckle noise model does not lead to a corruption of the useful information but to an improvement of its estimation. The performance of the algorithm is analyzed in terms of the physical parameters retrieved from the filtered data, that in this work correspond to the forest height and the ground phase. In case of experimental data, the retrieved forest height is compared and validated against Lidar ground truth measurements.

  • Transpolarizing trihedral corner reflector characterization using a GB-SAR system

     Ferrer, Pere J.; López Martínez, Carlos; Aguasca Sole, Alberto; Pipia, Luca; González Arbesú, José María; Fabregas Canovas, Francisco Javier; Romeu Robert, Jordi
    IEEE Geoscience and Remote Sensing Letters
    Date of publication: 2011-07
    Journal article

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    The use of a low-profile, lightweight, and easy-to-fabricate transpolarizing surface placed on one side of a trihedral corner reflector (TCR) as a polarimetric calibrator is presented in this letter. The transpolarizing TCR presents a high backscattered cross-polar response contrary to standard TCRs. The performance of this device has been tested at the X-band using the Universitat Politecnica de Catalunya ground-based synthetic aperture radar.

  • Separation of scattering contributions in Polarimetric SAR Interferometry

     López Martínez, Carlos; Papathanassiou, Kostantinos; Fabregas Canovas, Francisco Javier; Alonso Gonzalez, Alberto
    International Workshop on Science and Applications of SAR Polarimetry and Polarimetric Interferometry
    Presentation's date: 2011-01
    Presentation of work at congresses

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  • Underlying topography estimation and separation of scattering contributions over forests based on polInSAR data

     López Martínez, Carlos; Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier; Papathanassiou, Kostantinos
    Advances in the Science and Applications of SAR Interferometry
    Presentation's date: 2011-09-20
    Presentation of work at congresses

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    The work detailed in this paper analyzes the topographic phase retrieval process on forested areas by means of Polarimetric Interferometric SAR data. On the basis of the Random Volume over Ground scattering model, an alternative implementation for the retrieval of the topographic phase, avoiding the bias introduced by the volumetric scattering components is presented.

  • 2D atmospheric artifact compensation with multiple regression model in ground-based sar over mountainous areas

     Fabregas Canovas, Francisco Javier; Iglesias González, Rubén; Aguasca Sole, Alberto; Gili Ripoll, Jose Antonio
    Advances in the Science and Applications of SAR Interferometry
    Presentation's date: 2011-09-20
    Presentation of work at congresses

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    Differential SAR interferometry with orbital, airborne and ground-based sensors  Open access

     Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; Broquetas Ibars, Antoni; Fabregas Canovas, Francisco Javier; López Martínez, Carlos; Alonso Gonzalez, Alberto; Iglesias, Rubén; Centolanza, Giuseppe; Monells Miralles, Daniel
    SAR Technologies & Applications Congress
    Presentation's date: 2011-05-30
    Presentation of work at congresses

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    • Introduction to Differential Interferometry • Orbital Sensors: ERS, ENVISAT, RADARSAT2, TerraSAR-X. • Airborne Sensors: DLR’s E-SAR • Ground-Based Sensors: UPC’s GB-SAR • Conclusions

  • Temporal and incidence angle dependency of PolSAR data for agricultural land cover analysis and characterization

     Montero, Ismael; López Martínez, Carlos; Fabregas Canovas, Francisco Javier
    International Workshop on Science and Applications of SAR Polarimetry and Polarimetric Interferometry
    Presentation's date: 2011-01
    Presentation of work at congresses

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  • Analysis of volumetric scatters based on TanDEM-X polarimetric interferometric SAR data

     López Martínez, Carlos; Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier; Papathanassiou, Kostantinos
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2011-07
    Presentation of work at congresses

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    Polarimetric SAR Interferometry makes possible a detailed analysis of the volumetric scattering processes present in microwave scattering in case of forest areas. In previous contributions, the authors, under the hypothesis of the RVoG coherent scattering model, developed a process for the direct extraction of the ground topography. In this paper, the authors present a generalization of this technique allowing to determine a set of scattering mechanisms making possible an optimization process for the estimation of the ground topography. The applicability of this technique, in case of X-band polarimetric SAR interferometric data, is explored considering data obtained in the frame of the TanDEM-X mission.

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    Analysis of wind turbines blockage on doppler weather radar beams  Open access

     Belmonte Molina, Aniceto; Fabregas Canovas, Francisco Javier
    IEEE antennas and wireless propagation letters
    Date of publication: 2010-07-01
    Journal article

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  • Estudio de viabilidad de la estimación cuantitativa de parámetros de nieve mediante técnicas de teledetección (EOSWAN)

     Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier; Broquetas Ibars, Antoni; Mallorqui Franquet, Jordi Joan; López Martínez, Carlos
    Participation in a competitive project

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  • Estimación de topografía en zonas boscosas mediante PolInSAR

     López Martínez, Carlos; Papathanassiou, Kostantinos; Fabregas Canovas, Francisco Javier; Alonso, Alberto
    Latin American Remote Sensing Week
    Presentation's date: 2010-10-07
    Presentation of work at congresses

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  • Impact analysis of wind turbines blockage on doppler weather radar

     Belmonte Molina, Aniceto; Fabregas Canovas, Francisco Javier
    European Conference on Antennas and Propagation
    Presentation's date: 2010-04-14
    Presentation of work at congresses

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  • Ground topography retrieval on forested areas based on polarimetric SAR interferometry

     López Martínez, Carlos; Fabregas Canovas, Francisco Javier; Alonso Garcia, Alberto; Papathanassiou, Kostantinos
    European Conference on Synthetic Aperture Radar
    Presentation's date: 2010-06-09
    Presentation of work at congresses

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    The work shown in this paper analyzes the topographic phase retrieval process on forested areas by means of Polarimetric Interferometric SAR (PolInSAR) data. On the basis of the Random Volume over Ground scattering model, an alternative implementation for the retrieval of the topographic phase, avoiding the bias introduced by the volumetric scattering components is presented. An evaluation based on simulated data is presented, where preliminary results show the capacity to retrieve the topographic phase, unambiguously and without the effect of the volume contribution. Results based also in experimental PolInSAR data acquired with the ESAR DLR’s system are presented.

  • Access to the full text
    Ground topography estimation on over forests considering polarimetric SAR interferometry  Open access

     López Martínez, Carlos; Alonso Gonzalez, Alberto; Fabregas Canovas, Francisco Javier; Papathanassiou, Kostantinos
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2010-07
    Presentation of work at congresses

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    The work detailed in this paper analyzes the topographic phase retrieval process on forested areas by means of Polarimetric Interferometric SAR data. On the basis of the Random Volume over Ground scattering model, an alternative implementation for the retrieval of the topographic phase, avoiding the bias introduced by the volumetric scattering components is presented.

  • LIVING WITH LANDSLIDE RISK IN EUROPE:ASSESSMENT, EFFECTS OF GLOBAL CHANGE AND RISK MANAGEMENT STRATEGIES

     Romero Morales, Enrique Edgar; Pinyol Puigmarti, Nuria Merce; Baeza Adell, Cristina; Mallorqui Franquet, Jordi Joan; Aguasca Sole, Alberto; Moya Sanchez, Jose; Lantada Zarzosa, Nieves; Lloret Morancho, Antonio; Ledesma Villalba, Alberto; Gili Ripoll, Jose Antonio; Alonso Pérez de Agreda, Eduardo; Fabregas Canovas, Francisco Javier; Olivella Pastalle, Sebastian; Hürlimann Ziegler, Marcel; Corominas Dulcet, Jordi
    Participation in a competitive project

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  • CONCEPTOS AVANZADOS EN TELEDETECCION ACTIVA Y PASIVA DE MICROONDAS: TECNOLOGIA Y APLICACIONES

     Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Mallorqui Franquet, Jordi Joan; Duffo Ubeda, Nuria; Aguasca Sole, Alberto; Broquetas Ibars, Antoni; López Martínez, Carlos; Fabregas Canovas, Francisco Javier
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  • Transpolarizing trihedral measurement using UPC X-band GB-SAR

     Ferrer González, Pere J.; Romeu Robert, Jordi; González Arbesú, José María; Aguasca Sole, Alberto; López Martínez, Carlos; Pipia, Luca; Fabregas Canovas, Francisco Javier
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation of work at congresses

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  • High-compacted FM-CW SAR for boarding on small UAVs

     Acevo Herrera, René; Aguasca Sole, Alberto; Mallorqui Franquet, Jordi Joan; Fabregas Canovas, Francisco Javier
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2009-07
    Presentation of work at congresses

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  • UWB Tomographic Radar Imaging of Penetrable and Impenetrable Objects

     Jofre Roca, Luis; Broquetas Ibars, Antoni; Romeu Robert, Jordi; Blanch Boris, Sebastian; Toda, Ap; Fabregas Canovas, Francisco Javier
    Proceedings of the IEEE
    Date of publication: 2009-02
    Journal article

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  • Polarimetric differential SAR interferometry: first results with ground-based measurements

     Pipia, L; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; Lopez-Martinez, C; Duque Biarge, Sergio; Mallorqui Franquet, Jordi Joan
    IEEE Geoscience and Remote Sensing Letters
    Date of publication: 2009-01
    Journal article

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  • Polarimetric differential SAR interferometru with ground-based sensors  Open access

     Pipia, Luca
    Defense's date: 2009-09-18
    Department of Signal Theory and Communications, Universitat Politècnica de Catalunya
    Theses

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    Las técnicas de Interferometría Diferencial se basan en la combinación de varias imágenes SAR con distinta separación temporal y permiten la recuperación de las componentes lineales y no-lineales del proceso de deformación ocurrida en el entorno de interés durante el entero periodo de observación. Condición imprescindible para una correcta estimación de los fenómenos geodéticos es la elevada estabilidad de la plataforma que embarca el sensor SAR. Por esta razón, a nivel operativo se utilizan datos SAR satelitales.El objetivo de la Polarimetría SAR es describir el entorno de interés analizando las propiedades de la señal que éste dispersa cuando se utilizan diferentes combinaciones de polarización de las antenas transmisora y receptora, definidas canales polarimétricos. La polarimetría interferométrica SAR junta la capacidad de la polarimetría de separar mecanismos de dispersión independientes con la sensibilidad de la Interferometría a la altura de los correspondientes centros de fase, y permite describir la distribución volumétrica de los dispersores dentro de la escena observada. Debido a la falta de conjuntos de datos polarimétricos SAR satelitales que cubran tramos temporales suficientemente largos, hay aún un gran interés en las mejoras que la polarimetría podría aportar a técnicas ya consolidadas como las de Interferometría Diferencial.La actividad de investigación que se presentará en esta tesis doctoral abarca, por primera vez conjuntamente, las dos áreas de la Polarimetría SAR y de la Interferometría Diferencial utilizando el sensor radar terrestre de corto alcance (gbSAR) desarrollado por la Universitat Politècnica de Catalunyua (UPC). El trabajo constará de dos bloques principales.El primer bloque describirá las técnicas que se han desarrollado para convertir el sistema UPC gbSAR en un instrumento operativo y simplificar la utilización de sus adquisiciones, incluyendo la formulación matemática de los principios de funcionamiento del sistema, la cadena de procesado de los raw data y su calibración polarimétrica, los procedimientos de georeferenciación, y las técnicas de compensación de los artefactos atmosféricos presentes en sus medidas diferenciales.La segunda parte se ocupará de demostrar los beneficios que los datos SAR polarimétricos ofrecen respecto a la medición de un único canal polarimétrico para aplicaciones diferenciales. A fin de llevar a cabo esta tarea, se analizarán los datos gbSAR adquiridos durante una campaña de medidas de un año realizada en el pueblo de Sallent, en Cataluña, afectado por un fenómeno de subsidencia. En esta parte se analizarán tres temas principales. El primero es el comportamiento no estacionario en tiempo del entorno urbano bajo la geometría de observación del sensor terrestre. Se estudiarán en detalle los efectos de su inestabilidad y se propondrá una técnica de filtrado novedosa entallada a las propiedades de los blancos deterministas con el fin de preservar la información de la fase diferencial. El segundo tema abarca el problema de los efectos de troposfera en datos diferenciales con separación temporal superior al mes y de su separación de las variaciones de fase inducidas por el proceso de deformación. El tercer tema es la utilización de toda la información polarimétrica diferencial. Con fin de superar las limitaciones propias de las técnicas DInSAR clásicas, se propondrá un nuevo modelo polarimétrico de dispersión y se demostrarán las ventajas de la nueva formulación enseñando la mejor estimación del proceso de subsidencia en Sallent. En la parte final de este apartado se explorará también el potencial de las técnicas polarimétricas de optimización de la coherencia para aplicaciones diferenciales.

    Differential SAR interferometry (DInSAR) deals with the combination of multi-temporal SAR images for the estimation of the linear and non-linear components of the deformation process within an area of interest during the whole observation period. A high stability of the platform is required for a reliable estimation of the geodetic phenomena. Accordingly, space-borne SAR images are operatively employed for DInSAR estimation, air-borne DInSAR still constituting a challenging research issue. SARPolarimetry aims at charactering the illuminated area through the analysis of its response under different combinations of transmitting and receiving antennas polarization, called polarimetric channels. The Polarimetric SAR Interferometry joins the capability of Polarimetry to separate independent scattering mechanisms and the sensitivity of Interferometry to the corresponding phase centers' elevation, making it possible to describe the volumetric distribution of the scatterers within the observed area. Owing to the lack of long-time collections of polarimetric space-borne SAR data, the studies carried out in this research field have been mainly based on air-borne acquisitions. Yet, there is a great expectation for the improvements that polarimetry may bring to assessed single-polarization techniques such as the DinSAR.The research described in this PhD dissertation fills for the first time the gap between SAR Polarimetry and SAR Differential Interferometry through the employment of an X-band ground-based SAR (gbSAR) sensor developed by the Remote Sensing Lab of the Universitat Politècnica de Catalunya (UPC).The work is divided into two main blocks. The first part deals with the algorithms that have been developed to make the UPC system operative and its acquisitions easy to use. Summarily, they include the mathematical formulation of the sensor's working principles, the raw data processing chain and the polarimetric calibration method, the geocoding procedures, and the techniques compensating for the atmospheric artefacts affecting gbSAR zero-baseline acquisitions.The second part is concerned with demonstrating the benefits that polarimetric SAR measurements provide with respect to single-polarization data for differential applications. In order to cope with this task, the data sets acquired during a one-year measurement campaign carried out in the village of Sallent, northeastern Spain, are analyzed. The experiment was focused on monitoring the subsidence phenomenon affecting a district of the village with the UPC gbSAR sensor. Three main issues are here argued. The first one is the time non-stationary behaviors characterizing the urban environment at X-band in the gbSAR observation geometry. Their effects are analyzed in detail and a novel non-stationary filtering technique tailored to deterministic scatterers' properties is introduced to preserve the differential phase information. The second one is the compensation of the troposphere changes in long-time span gbSAR differential interferograms. A new technique is worked out to effectively separate the differential phase variations due to the atmospheric artefacts from the deformation components. The third one is the use of the whole polarimetric differential information. A novel polarimetric differential scattering model is put forward to relax the constraints of an advanced DInSAR technique, the Coherent Pixel Technique, and to propose an innovative polarimetric approach. The advantages offered by Polarimetric DInSAR are demonstrated in terms of quality of the deformation-rate map describing the subsidence phenomenon in Sallent. In the end, the potentials of coherence-optimization techniques for the further improvement of the deformation process estimation are stressed.

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    PolSAR and PolInSAR model based information estimation  Open access

     López Martínez, Carlos; Fabregas Canovas, Francisco Javier; Pipia, Luca
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2009-07
    Presentation of work at congresses

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    Speckle for multidimensional SAR data may be modeled as the combination of multiplicative and additive noise sources. As demonstrated, the use of this noise model does not corrupt the estimation of physical information from PolInSAR data. The definition of a model based PolInSAR filter allows also the computation of relative errors for estimated heights of forested areas from PolInSAR data.

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    Polarimetric coherence optimization for interferometric differential applications  Open access

     Pipia, Luca; Fabregas Canovas, Francisco Javier; Aguasca Sole, Alberto; López Martínez, Carlos; Mallorqui Franquet, Jordi Joan
    IEEE International Geoscience and Remote Sensing Symposium
    Presentation's date: 2009-07
    Presentation of work at congresses

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    In this paper, the potentials of polarimetric coherenceoptimization techniques for differential interferometric SAR (DInSAR) applications are examined. For this purpose, the cutting-edge approaches available in the literature are considered. First, synthetic PolSAR data simulating homogeneous distributed scatterers are employed to demonstrate the convergence of the optimized differential phase to the deformation phase information. Then, real X-band ground-based PolSAR acquisitions concerning an urban environment are analyzed. The relation between optimum coherences and corresponding optimum phase in terms of deformation on retrieval is carefully analyzed using two zero-baseline fullypolarimetric data sets. In the end, general conclusions about the advantages and drawbacks of the alternative maximization approaches are drawn.