Ara es mostren els items 87-106 de 216

    • Ill conditioning loci in noise parameter determination 

      O'Callaghan Castellà, Juan Manuel; Alegret, A.; Pradell i Cara, Lluís; Corbella Sanahuja, Ignasi (IEE-INST ELEC ENG, 1996-08-01)
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      An analysis of the problem of noise parameter determination is carried out. It is found that the mathematical problem is ill-posed if all the source reflection coefficients (Γs) used in the measurements fall onto a line, ...
    • Ill conditioning loci in noise parameter determination 

      O'Callaghan Castellà, Juan Manuel; Alegret Ginesta, Alexandre; Pradell i Cara, Lluís; Corbella Sanahuja, Ignasi (IEE-INST ELEC ENG, 1996-08-01)
      Article
      Accés obert
      An analysis of the problem of noise parameter determination is carried out. It is found that the mathematical problem is ill-posed if all the source reflection coefficients (Γs) used in the measurements fall onto a line, ...
    • Impact of amplitude calibration errors on SMOS global images 

      Durán Martínez, Israel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Oliva, Roger; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2016)
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      Some of the artifacts observed in SMOS brightness temperature images are originated in an inconsistency between correlation and antenna temperature calibration errors, which produces a multiplicative bias that scales with ...
    • Impact of antenna errors on the radiometric accuracy of large aperture synthesis radiometers 

      Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Romeu Robert, Jordi (1997-04)
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      Accés restringit per política de l'editorial
      A classification of system errors in aperture synthesis radiometry applied to Earth observation is presented. A general procedure to quantify the impact of antenna errors on the radiometric accuracy is developed and is ...
    • Impact of antenna errors on the radiometric accuracy of large aperture synthesis radiometers. Study applied to MIRAS 

      Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Romeu Robert, Jordi (American Geophysical Union, 1997-04-30)
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      Accés obert
      A classification of system errors in aperture synthesis radiometry applied to Earth obervation is presented. A general procedure to quantify th eimpact of antenna errors on the radiometric accuracy is developed and is then ...
    • Impact of antenna tuning on SMOS correlation loss 

      Torres Torres, Francisco; Durán Martínez, Israel; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Closa, Josep; Oliva, Roger; Martín-Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2016)
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      The Soil Moisture and Ocean Salinity (SMOS) mission by the European Space Agency (ESA) was launched in 2009 [1]. Since then, it has produced a continuous stream of valuable geophysical data over land, ice and ocean [2] ...
    • Impact of correlator efficiency errors on SMOS land-sea contamination 

      Corbella Sanahuja, Ignasi; Durán Martínez, Israel; Wu, Lin; Torres Canals, Francesc; Duffo Ubeda, Núria; Khazaal, Ali; Martín Neira, Manuel (2015-09-01)
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      Accés obert
      Land-sea contamination observed in Soil Moisture and Ocean Salinity (SMOS) brightness temperature images is found to have two main contributions: the floor error inherent of image reconstruction and a multiplicative error ...
    • Impact of receiver errors on the radiometric resolution of large two-dimensional aperture synthesis radiometers 

      Torres Torres, Francisco; Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Corbella Sanahuja, Ignasi (1997-04)
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      Accés restringit per política de l'editorial
      The specifications of the subsystems that compound a radiometer interferometer devoted to Earth observation are of main concern because they set the viability and final performance of such an instrument. The importance of ...
    • Impact of the local oscillator calibration rate on the SMOS measurements and retrieved salinities 

      Gabarró Prats, Carolina; Gonzalez Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco (Institute of Electrical and Electronics Engineers (IEEE), 2013-09-02)
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      The local oscillators (LOs) of the Soil Moisture and Ocean Salinity mission payload are used to shift the operating frequency of the 72 receivers to an optimal intermediate frequency needed for the signal processing. ...
    • Improvement of the pull in range and acquisition time of a microwave PLL system by injection locking the V.C.O 

      Berenguer Sau, Jordi; Bara, Javier; Artal, Eduardo; Corbella Sanahuja, Ignasi (1987)
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      The requirements of large pull-in range and short acquisition time in microwave and millimeter wave phase locked oscillators are of great importance since the free running VCO frequency may be sorne tens of MHz off the ...
    • In-orbit validations of SMOS full polarimetric equations 

      Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Wu, Lin; Duffo Ubeda, Núria; Delwart, Steven; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2013)
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      This paper analyzes the consistency of SMOS fully polarimetric measurement mode by comparing measured data over the ocean with the expected results. These last are based on an accurate ocean model provided by LOCEAN and ...
    • Increasing stratification as observed by satellite sea surface salinity measurements 

      Olmedo Casal, Estrella; Turiel Martínez, Antonio; González Gambau, Verónica; González Haro, Cristina; García Espriu, Aina; Gabarró Prats, Carolina; Portabella, Marcos; Corbella Sanahuja, Ignasi; Martín Neira, Manuel; Arias Ballesteros, Manuel; Catany, Rafael; Sabia, Roberto; Olivia, Roger; Scipal, Klaus (Nature, 2022-12-01)
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      Changes in the Earth’s water cycle can be estimated by analyzing sea surface salinity. This variable refects the balance between precipitation and evaporation over the ocean, since the upper layers of the ocean are the ...
    • Instantaneous model of a MESFET for use in linear and nonlinear circuit simulations 

      Corbella Sanahuja, Ignasi; Legido, J.M.; Naval, G. (IEEE Microwave Theory and Techniques Society, 1992-07)
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      A formal approach for nonlinear modeling of FETs is presented. The intrinsic transistor is described by current and charge generators, that are instantaneously dependent on the two internal voltages. The extrinsic parasitic ...
    • Integration of MIRAS breadboard and future activities 

      Martín Neira, Manuel; Goutoule, J.M.; Knight, A.; Claude, J.; Bará Temes, Francisco Javier; Camps Carmona, Adriano José; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Lannes, A.; Anterrieu, E.; Laursen, B.; Skou, N. (1996)
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      The European Space Agency (ESA) is conducting a feasibility study on MIRAS, a Microwave Imaging Radiometer using two dimensional aperture synthesis, for the mapping of soil moisture and ocean salinity from space. An aircraft ...
    • Interferometric radiometry and its applications 

      Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena (1999)
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    • Interferometric radiometry measurement concept: The visibility equation 

      Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín-Neira, Manuel (IEEE, 2011)
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      The fundamental concept of interferometric aperture synthesis microwave radiometry for Earth observation is reviewed. The measurement principles and a discussion on the signal processing techniques for image reconstruction ...
    • L-band aperture synthesis radiometry: hardware requirements and system performance 

      Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Camps Carmona, Adriano José; Bará Temes, Francisco Javier; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena (IEEE Piscataway, 2000)
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      Aperture synthesis radiometry is becoming a feasible concept for imaging applications, especially at low microwave frequencies where it takes clear advantage of the absence of mechanical antenna motion. A 2D interferometric ...
    • L-Band sea surface emissivity: preliminary results of the WISE-2000 campaign and its application to salinity retrieval in the SMOS mission 

      Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Vall-Llossera Ferran, Mercedes Magdalena; Duffo Ubeda, Núria; Torres Torres, Francisco; Villarino Villarino, Ramón; Enrique, L; Julbé, F; Font Capafons, Josep; Julià, A; Gabarró, C; Etcheto, J; Boutin, J; Weill, A; Caselles Costa, Vicent; Rubio, E; Wursteisen, P (2003-06)
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      Accés obert
      Soil moisture and ocean salinity at surface level can be measured by passive microwave remote sensing at L-band. To provide global coverage data of soil moisture and ocean salinity with three-day revisit time, the Earth ...
    • L-Band Sea Surface Emissivity: Preliminary Results Of The WISE-2000 Campaign And Its Application To Salinity Retrieval In the SMOS Mission 

      Camps Carmona, Adriano José; Corbella Sanahuja, Ignasi; Vall-Llossera Ferran, Mercedes Magdalena; Duffo Ubeda, Núria; Torres Torres, Francisco; Villarino Villarino, Ramón; Enrique, L.; Julbé, F.; Font, Jordi; Julià, A.; Gabarró Prats, Carolina; Etcheto, Jacqueline; Boutin, Jacqueline; Weill, Alain; Caselles, Vicente; Rubio, Eva; Wursteisen, Patrick (2003-06-30)
      Article
      Accés obert
      Soil moisture and ocean salinity at surface level can be measured by passive microwave remote sensing at L-band. To provide global coverage data of soil moisture and ocean salinity with three-day revisit time, the Earth ...
    • Latitudinal and seasonal SMOS amplitude calibration assessment 

      Gonzalez Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Turiel, Antonio (Institute of Electrical and Electronics Engineers (IEEE), 2014)
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      The consistency of MIRAS amplitude calibration along the mission is a key issue to ensure a stable and accurate long-term dataset of ESA's SMOS soil moisture and ocean salinity data. Recent studies have revealed latitudinal ...