Exploració per autor "Martín Neira, Manuel"

Ara es mostren els items 9-28 de 72

    • Benefits of applying nodal sampling to SMOS data over semi-enclosed seas and strongly RFI-contaminated regions 

      González Gambau, Verónica; Olmedo, Estrella; Martinez, J.; Turiel, Antonio; Corbella Sanahuja, Ignasi; Oliva, Roger; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2018)
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      Radio Frequency Interferences (RFI) are still an important source of contamination in SMOS data. The application of nodal sampling (NS) to brightness temperature images helps to mitigate the degradation that RFIs produce ...

    • Calibration of the MIRAS Radiometers 

      Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Durán Martínez, Israel; González Gambau, Verónica; Oliva Balagué, Roger; Closa, Josep; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2018-12-21)
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      The microwave imaging radiometer with aperture synthesis (MIRAS) is formed by 69 total power radiometers, of which three are the noise-injection type. Their calibration is reviewed on the basis of the data gathered during ...

    • Comparison of GNSS-R processing techniques for spaceborne ocean altimetry 

      Martín Alemany, Francisco; d'Addio, Salvatore; Camps Carmona, Adriano José; Martín Neira, Manuel; Hyuk, Park; Pascual Biosca, Daniel (Institute of Electrical and Electronics Engineers (IEEE), 2013)
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      Earth-reflected Global Navigation Satellite System (GNSS) have become an attractive tool to be employed in low-Earth-orbit spaceborne missions, for applications such as ocean mesoscale altimetry and scatterometry. For such ...

    • Consolidating the precision of interferometric GNSS-R ocean altimetry using airborne experimental data 

      Cardellach, Estel; Rius, Antonio; Martín Neira, Manuel; Fabra Cervellera, Fran; Nogués Correig, O.; Ribó Vedrilla, Serni; Kainulainen, Juha; Camps Carmona, Adriano José; D'Addio, Salvatore (Institute of Electrical and Electronics Engineers (IEEE), 2014-08)
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      This paper revises the precision of altimetric measurements made with signals of the Global Navigation Satellite Systems (GNSS) reflected (GNSS-R) off the sea surface. In particular, we investigate the performance of two ...

    • Correcting the FRA systematic error in VTEC maps from SMOS radiometric data 

      Rubino, Roselena; Duffo Ubeda, Núria; González Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Oliva Balagué, Roger; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2022-10-17)
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      The Faraday rotation (FR) is a nonnegligible effect at the L-band, which is the operation frequency of the Soil Moisture and Ocean Salinity (SMOS) mission. This effect introduces a rotation in the electromagnetic field ...

    • Cross-correlation waveform analysis for conventional and interferometric GNSS-R approaches 

      Martín Alemany, Francisco; Camps Carmona, Adriano José; Hyuk, Park; d'Addio, Salvatore; Martín Neira, Manuel; Pascual Biosca, Daniel (2014-05-01)
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      Reflectometry using Global Navigation Satellite System (GNSS-R) signals has become an attractive tool for Earth remote sensing. Back to 1993, it was proposed as an alternative to the conventional spaceborne ocean altimetry ...

    • Cross-correlation waveform mode: a critical review 

      Martín Alemany, Francisco; Hyuk, Park; Camps Carmona, Adriano José; D'Addio, Salvatore; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2012)
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      Earth-reflected Global Navigation Satellite System (GNSS) signals have become an attractive tool for remote sensing. Recently it has been proposed as an alternative to the conventional altimetry to estimate the surface ...

    • Denormalization of visibilities for in-orbit calibration of interferometric radiometers 

      Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Camps Carmona, Adriano José; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena; Beraza Robledano, Santiago; Martín Neira, Manuel; Gutiérrez, C. (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-10-31)
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      This paper reviews the relative calibration of an interferometric radiometer taking into account the experimental results of the first batch of receivers developed in the frame of the European Space Agency's Soil Moisture ...

    • Denormalization of visibilities for in-orbit calibration of interferometric radiometers 

      Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Camps Carmona, Adriano José; Duffo Ubeda, Núria; Vall-Llossera Ferran, Mercedes Magdalena; Beraza Robledano, Santiago; Gutiérrez, C.; Martín Neira, Manuel (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2006-10-31)
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      Accés obert
      This paper reviews the relative calibration of an interferometric radiometer taking into account the experimental results of the first batch of receivers developed in the frame of the European Space Agency's Soil Moisture ...

    • Deriving VTEC maps from SMOS radiometric data 

      Rubino, Roselena; Duffo Ubeda, Núria; González Gambau, Verónica; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Durán Martínez, Israel; Martín Neira, Manuel (Multidisciplinary Digital Publishing Institute (MDPI), 2020-05-01)
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      In this work, a new methodology is proposed in order to derive vertical total electron content (VTEC) maps from the radiometric measurements of the Soil Moisture and Ocean Salinity (SMOS) mission as an alternative approach ...

    • Evaluation of MIRAS space borne instrument performance: snap shot radiometric accuracy and its improvement by means of pixel averaging 

      Camps Carmona, Adriano José; Torres Torres, Francisco; Bará Temes, Francisco Javier; Corbella Sanahuja, Ignasi; Martín Neira, Manuel (1997)
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    • Faraday rotation angle retrieval using SMOS radiometric data 

      Wu, Lin; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel (Institute of Electrical and Electronics Engineers (IEEE), 2014)
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      SMOS radiometric data is used to derive Faraday rotation for a number of orbits combining several scenarios: land, ice and water. Results compare very well with the values theoretically predicted from available ionosphere ...

    • Faraday rotation retrieval using SMOS radiometric data 

      Corbella Sanahuja, Ignasi; Wu, Lin; Torres Canals, Francesc; Duffo Ubeda, Núria; Martín Neira, Manuel (2015-03-01)
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      Faraday rotation is dynamically computed from L-band radiometric data acquired by the Soil Moisture and Ocean Salinity satellite. Improved full polarimetric image reconstruction and smart spatiotemporal filtering are used ...

    • GNSS-R altimeter based on Doppler multi-looking 

      D'Addio, Salvatore; Martín Neira, Manuel; di Bisceglie, Maurizio; Galdi, Carmela; Martín Alemany, Francisco (2014-05-01)
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      Measuring ocean mesoscale variability is one of the main objectives of next generation satellite altimeters. Current radar altimeters make observations only at the nadir sub-satellite ground track, which is not sufficient ...

    • GNSS-R altimeter performance: analysis of Cramer-Rao lower bounds 

      D'Addio, Salvatore; Martín Neira, Manuel; Martín Alemany, Francisco; Hyuk, Park; Camps Carmona, Adriano José (2012)
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      Earth-reflected Global Navigation Satellite Systemsignals have become an attractive tool for remote sensing, being proposed as a means to perform ocean altimetry, among many other applications. The technique exploiting ...

    • 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 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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      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 ...

    • 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 ...

    • 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 ...