211 results on '"Corbella, Ignasi"'
Search Results
2. TriHex: combining formation flying, general circular orbits and alias-free imaging, for high resolution L-band aperture synthesis
- Author
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Martin-Neira, Manuel, primary, Scala, Francesca, additional, Zurita, Albert, additional, Suess, Martin, additional, Piera, Miguel, additional, Duesmann, Berthyl, additional, Drusch, Matthias, additional, Colombo, Camilla, additional, De Wilde, Don, additional, Closa, Josep, additional, Gandini, Erio, additional, Díez-García, Raúl, additional, Oliva, Roger, additional, and Corbella, Ignasi, additional
- Published
- 2023
- Full Text
- View/download PDF
3. Correcting the FRA Systematic Error in VTEC Maps From SMOS Radiometric Data
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Rubino, Roselena, primary, Duffo, Nuria, additional, Gonzalez-Gambau, Veronica, additional, Corbella, Ignasi, additional, Torres, Francesc, additional, Oliva, Roger, additional, and Martin-Neira, Manuel, additional
- Published
- 2022
- Full Text
- View/download PDF
4. Detecció de mascaretes en cares mitjançant visió per computador
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Cervero Corbella, Ignasi, Universitat Politècnica de Catalunya. Departament d'Enginyeria de Sistemes, Automàtica i Informàtica Industrial, and Grau Saldes, Antoni
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Neural networks (Computer science) ,TensorFlow ,Enginyeria electrònica [Àrees temàtiques de la UPC] ,Mascaretes ,Xarxes neuronals (Informàtica) ,OpenCV ,Detecció de mascaretes ,xarxa neuronal SSD ,Python - Abstract
Es presenta el disseny i la implementació d’un sistema de detecció de cares amb i sense mascareta, preparat per poder ser exportat en diferents plataformes. S’ha desenvolupat amb TensorFlow i amb la llibreria OpenCV mitjançant els llenguatges de programació Python i C++. El model prèviament entrenat SSD MobileNet V2 FPNLite 320x320 ha estat la base de l’entrenament de la xarxa neuronal. L’entrenament s’ha dut a terme a partir d’una base d’imatges àmplia i diversa, construïda gràcies a la creació d’un procés automatitzat que, donades imatges de cares sense mascareta, es generen cares amb mascareta de diferents tipus, colors i contrasts. A més a més, s’ha augmentat aquesta base d’imatges amb altres processos automatitzats, com el canvi aleatori de la brillantor de la imatge o el redimensionament i col·locació de les cares amb mascareta generades sobre fons aleatoris. Aquestes accions permeten aconseguir més robustesa per a imatges amb múltiples il·luminacions, així com per a cares de diverses mides i col·locades en diferents parts de la imatge. La situació de la pandèmia de la COVID-19 fa que l’eina pugui tenir diverses aplicacions mentre l’ús de les mascaretes sigui obligatori en espais tancats. Des de control de l’entrada en una porta automàtica a aportar informació a una persona amb visibilitat reduïda. Se presenta el diseño y la implementación de un sistema de detección de caras con y sin mascarilla, preparado para poder ser exportado en diferentes plataformas. Se ha desarrollado con TensorFlow y con la librería OpenCV mediante los lenguajes de programación Python y C++. El modelo previamente entrenado SSD MobileNet V2 FPNLite 320x320 ha sido la base del entrenamiento de la red neuronal. El entrenamiento se ha llevado a cabo a partir de una base de imágenes amplia y diversa, construida gracias a la creación de un proceso automatizado que, dadas imágenes de caras sin mascarilla, se generan caras con mascarilla de diferentes tipos, colores y contrastes. Además, se ha aumentado esta base de imágenes con otros procesos automatizados como el cambio aleatorio del brillo de la imagen o el redimensionamiento y la colocación de las caras con mascarilla generadas sobre fondos aleatorios. Estas acciones permiten conseguir mas robustez para imágenes con múltiples iluminaciones, así como para caras de varios tamaños y colocadas en diferentes partes de la imagen. La situación de la pandemia de la COVID-19 hace que la herramienta pueda tener varias aplicaciones mientras el uso de las mascarillas sea obligatorio en espacios cerrados. Desde control de la entrada en una puerta automática a aportar información a una persona con visibilidad reducida. The design and implementation of a face wearing and not wearing a face mask detection system are presented, prepared to be exported for different platforms. It has been developed with TensorFlow and with the OpenCV library using the Python and C++ program languages. The pre-trained model SSD MobileNet V2 FPNLite 320x320 has been the basis of neural network training. The model has been trained from a wide and diverse dataset, built by the creation of an automated process which, given images of faces not wearing a face mask, generate faces wearing a face mask of different types, colors, and contrasts. In addition, this dataset has been increased with other automated processes, such as random change in image brightness or resizing and placing faces with a mask on random backgrounds. These actions provide more robustness for images with multiple illuminations, as well as for faces of various sizes and placed in different parts of the image. The situation of the COVID-19 pandemic makes the tool able to have several applications while the use of masks is mandatory in enclosed spaces. From input control on an automatic door to provide information to a person with reduced visibility. Objectius de Desenvolupament Sostenible::3 - Salut i Benestar
- Published
- 2021
5. A Novel Digital IQ Demodulation for Interferometric Radiometers
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Corbella, Ignasi, primary, Martín Neira, Manuel, additional, Vilaseca, Roger, additional, Catalan, Albert, additional, Torres, Francesc, additional, and Suess, Martin, additional
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- 2021
- Full Text
- View/download PDF
6. On-ground characterization of the SMOS payload
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Corbella, Ignasi, Torres, Francesc, Duffo, Nuria, Martin-Neira, Manuel, Gonzalez-Gambau, Veronica, Camps, Adriano, and Vall-llossera, Merce
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Microwave radiometers -- Usage ,Interferometry -- Technology application ,Soil moisture -- Measurement ,Salinity -- Measurement ,Technology application ,Business ,Earth sciences ,Electronics and electrical industries - Published
- 2009
7. Correlation denormalization in interferometric or polarimetric radiometers: a unified approach
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Colliander, Andreas, Torres, Francesc, and Corbella, Ignasi
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Interferometry -- Methods ,Microwave radiometers -- Design and construction ,Microwave radiometers -- Usage ,Correlation (Statistics) -- Methods ,Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
This paper presents a general analysis of correlation measurements in an interferometer or a radiometer based on noise injection and/or switching and measurement of normalized correlations (e.g., imaging synthetic aperture or polarimetric radiometers). A compact unifying notation for denormalizing the measured normalized correlations in the presence of noise injection in one or both of the receiving channels is presented. Technological limitations are also assessed by evaluating the effect of associated approximations. Finally, the approach is validated by experimental results of the measurement and calibration of related front-end nonidealities, namely, the finite isolation of the front-end switch. The methods presented in this paper are illustrated by a thorough analysis of the so-called mixed baselines of microwave imaging radiometer using aperture synthesis, which refer to those baselines which are formed between the regular receivers (light-weight cost-efficient front-end) and the reference radiometers. These baselines require special attention, since the reference radiometers are noise-injection radiometers, which inject noise to the measured signal, whereas the regular receivers are total power receivers. Index Terms--Denormalization, interferometric radiometry, Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), polarimetric radiometer, synthetic aperture radiometry.
- Published
- 2009
8. Brightness-temperature retrieval methods in synthetic aperture radiometers
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Corbella, Ignasi, Torres, Francesc, Camps, Adriano, Duffo, Nuria, and Vall-llossera, Merce
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Radiometers -- Analysis ,Synthetic aperture radar -- Analysis ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
Brightness-temperature retrieval techniques for synthetic aperture radiometers are reviewed. Three different approaches to combine measured visibility and antenna temperatures, along with instrument characterization data, into a general equation to invert are presented. Discretization and windowing techniques are briefly discussed, and formulas for reciprocal grids using rectangular and hexagonal samplings are given. Two known techniques are used to invert the equation, namely, inverse Fourier transform and G-matrix pseudoinverse. The proposed preprocessing approaches combined with these two inversion methods are implemented with real data measured by an airborne Y-shaped interferometric radiometer over land and water, and are compared. The images indicate that best results are obtained when inverting an incremental visibility obtained after substracting a term that includes the individual antenna temperatures, the physical temperatures of the receivers, and a flat-target response directly measured from cold-sky looks. Index Terms--Brightness temperature image reconstruction, interferometry, synthetic aperture microwave radiometers.
- Published
- 2009
9. AMIRAS--an airborne MIRAS demonstrator
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Martin-Neira, Manuel, Cabeza, Isabel, Perez, Cesar, Palacios, Miguel Angel, Guijarro, Miguel Angel, Ribo, Serni, Corbella, Ignasi, Blanch, Sebastian, Torres, Francesc, Duffo, Nuria, Gonzalez, Veronica, Beraza, S., Camps, Adriano, Vall-llossera, Merce, Tauriainen, Simo, Pihlflyckt, Jorgen, Gonzalez, Jesus Pablo, and Martin-Porqueras, Fernando
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Soil moisture -- Observations ,Salinity -- Observations ,Holes -- Observations ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
This paper describes AMIRAS, an airborne demonstrator of the Microwave Imaging Radiometer with Aperture Synthesis, which is the instrument onboard ESA's Soil Moisture and Ocean Salinity (SMOS) mission. The main electrical, mechanical, thermal, and control elements of the demonstrator are shown, together with its capabilities and performances as demonstrator of the spaceborne instrument. AMIRAS main tests inside an anechoic chamber, field ground experiments, and its first two maiden flights are reported, and some results of these tests are highlighted. AMIRAS will further be used in some calibration and validation campaigns of the SMOS mission. Index Terms--Aperture synthesis, microwave imaging radiometer with aperture synthesis (MIRAS), microwave radiometry, Soil Moisture and Ocean Salinity (SMOS).
- Published
- 2008
10. SMOS calibration
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Brown, Michael A., Torres, Francesc, Corbella, Ignasi, and Colliander, Andreas
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Soil moisture -- Analysis ,Soil moisture -- Observations ,Salinity -- Observations ,Salinity -- Analysis ,Geophysical research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
The calibration of the Soil Moisture and Ocean Salinity (SMOS) payload instrument, known as Microwave Imaging Radiometer by Aperture Synthesis (MIRAS), is based on characterization measurements which are performed initially on-ground prior to launch and, subsequently, in-flight. A good calibration is a prerequisite to ensure the quality of the geophysical data. The calibration scheme encompasses both the spaceborne instrument and the ground data processing. Once the system has been calibrated, the instrument performance can be verified, and the higher level geophysical variables, soil moisture and ocean salinity, can be validated. In this paper, the overall calibration approach is presented, focusing on the main aspects relevant to the SMOS instrument design and mission requirements. The distributed instrument, comprising 72 receivers, leads to a distributed internal calibration approach supported by specific external calibration measurements. The relationship between the calibration data and the routine ground processing is summarized, demonstrating the inherent link between them. Finally, the approach to the in-flight commissioning activities is discussed. Index Terms--Calibration, Microwave Imaging Radiometer by Aperture Synthesis (MIRAS), Soil Moisture and Ocean Salinity (SMOS), verification.
- Published
- 2008
11. Improved image reconstruction algorithms for aperture synthesis radiometers
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Camps, Adriano, Vall-llossera, Merce, Corbella, Ignasi, Duffo, Nuria, and Torres, Francesc
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Business ,Earth sciences ,Electronics and electrical industries - Abstract
The European Space Agency's Soil Moisture and Ocean Salinity (SMOS) mission aims at producing global and frequent maps of SMOS and will be launched in 2008. SMOS' single payload is a new type of radiometer called Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) operating at L-band in which brightness temperature images are formed by a Fourier synthesis technique. However, in the alias-free field of view where the brightness temperature images are reconstructed, a bias is present which has been found to be higher for high-contrast brightness temperature scenes (coastlines) and lower for homogeneous scenes (all oceans or lands). This scene-dependent bias will ultimately limit the achievable accuracy of the retrieved geophysical parameters, and it is particularly critical for the retrieval of sea surface salinity. This paper presents a general analysis of the origin of this bias, which is found to be actually due to the different measurement errors in the instrument observables (visibility samples). An improvement of the image reconstruction algorithm is then presented to mitigate it. As compared with the previous algorithm versions, the proposed improved reconstruction algorithm further decomposes the visibility samples into some new terms: ocean and land/iced sea, instead of just the Earth's disk over the sky background. This decomposition aims at further reducing the contrast (high-frequency components) in the differential image and, therefore, minimizes the impact of multiplicative errors, improving the radiometric accuracy. In addition, this approach proves to perform the image reconstruction in part of the alias regions and improves the quality of the reconstruction close to the coastlines. Index Terms--Aperture synthesis radiometers, bias, errors, image reconstruction, soil moisture and ocean salinity ISMOS).
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- 2008
12. Retrieving the vertical total electron content to correct the faraday rotation angle in SMOS
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Rubino, Roselena, Duffo, Nuria, González Gambau, Verónica, Corbella, Ignasi, Torres, Francesc, and Martín-Neira, Manuel
- Abstract
16th Specialist Meeting on on Microwave Radiometry and Remote Sensing of the Environment, 16-20 November 2020
- Published
- 2020
13. SMOS instrument calibration and level-1 processor performance after 10 years in orbit
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Martín-Neira, Manuel, Oliva, Roger, Corbella, Ignasi, Torres, Francesc, Duffo, Nuria, Durán, Israel, Kainulainen, J., Closa, Josep, Zurita, Albert, Cabot, François, Khazaal, Ali, Anterrieu, Eric, Richaume, Philippe, Lopes, Gonçalo, Díez-García, Raúl, Fauste, Jorge, Turiel, Antonio, González Gambau, Verónica, Crapolicchio, Raffaele, Macelloni, Giovanni, Brogioni, Marco, Vogel, Pierre, Suess, Martin, Cerro Herrero, Irene, and Checa Cortés, Elena
- Abstract
16th Specialist Meeting on on Microwave Radiometry and Remote Sensing of the Environment, 16-20 November 2020
- Published
- 2020
14. Denormalization of visibilities for in-orbit calibration of interferometric radiometers
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Torres, Francesc, Corbella, Ignasi, Camps, Adriano, Duffo, Nuria, Vall-llossera, Merce, Beraza, Santiago, Gutierrez, Carles, and Martin-Neira, Manuel
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Interferometry -- Research ,Salinity -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
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 and Ocean Salinity mission. Measurements show state-of-the-art baseline performance as long as the system is capable of correcting the effect of orbital temperature swing. A method to validate internal calibration during in-orbit deep-sky views and to correct linearity errors is also presented. Index Terms--Calibration, interferometry, radiometer.
- Published
- 2006
15. Analysis of correlation and total power radiometer front-ends using noise waves
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Corbella, Ignasi, Torres, Francesc, Camps, Adriano, Duffo, Nuria, Vall-llossera, Merce, Rautiainen, Kimmo, Martin-Neira, Manuel, and Colliander, Andreas
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Correlation (Statistics) -- Analysis ,Radiation -- Measurement ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
A complete and systematic noise analysis of radiometer front-ends, including both total power and correlation measurements, is presented. The procedure uses the concepts of noise waves and S-parameters, widely used in microwave systems design and takes into account full noise characterization of receivers including mismatch effects. The general formulation is compatible with known total power radiometer analysis and is specially appropriate in correlation radiometers for which the effect of nonideal components, such as input isolators, is analyzed. Along with numerical simulations, simple formulas are given to compute the measured visibility in nonideal conditions. The analysis is validated using experimental results consisting of correlation measurements of four receivers placed inside an anechoic chamber. Good agreement between theoretical predictions and experimental data is observed. Index Terms--Interferometric aperture synthesis radiometry, microwave radiometry, polarimetric radiometry, radiometer calibration.
- Published
- 2005
16. Performance of sea surface salinity and soil moisture retrieval algorithms with different auxiliary datasets in 2-D L-band aperture synthesis interferometric radiometers
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Camps, Adriano, Vall-llossera, Merce, Duffo, Nuria, Torres, Francesc, and Corbella, Ignasi
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Soils -- Research ,Remote sensing -- Research ,Algorithms -- Technology application ,Algorithm ,Technology application ,Business ,Earth sciences ,Electronics and electrical industries ,European Space Agency - Abstract
The Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Opportunity Mission was selected in May 1999 by the European Space Agency Earth Observation Programme Board to provide global and frequent soil moisture (SM) and sea surface salinity (SSS) maps. SMOS' single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) sensor, an L-band two-dimensional aperture synthesis interferometric radiometer with multiangular and polarimetric imaging capabilities. The definition of the SMOS Level 2 Processor requires the selection of the optimum operation mode (dual-polarization or full-polarimetric) for each application, the specification of the required auxiliary data, and the optimum retrieval algorithms. Using the SMOS simulator and based on the experience gained in previous works, this paper presents a study of the SM and SSS retrieval capabilities over homogeneous pixels, in the two modes of operation with different auxiliary data. It is found that SSS retrievals using the first Stokes parameter measured in the dual-polarization mode perform somewhat worse than using the vertical ([T.sub.vv]) and horizontal ([T.sub.hh]) brightness temperatures measured in the full-polarimetric mode, and the performance degrades for cold waters due to the lower sensitivity of the brightness temperature to SSS at low sea surface temperature (SST). Due to the larger angular variation of [T.sub.hh] and [T.sub.vv], SM retrievals using [T.sub.hh] and [T.sub.vv] measured in the full-polarimetric mode exhibit a significant better performance over bare soils than over vegetation-covered soils. Over vegetation-covered soils vegetation parameters (opacity and albedo) can be inferred over a 550-km swath width in the full-polarimetric mode. However, since the first Stokes parameter is independent of both geometric and Faraday rotations, it is very robust in the presence of instrumental and geophysical errors. In the SSS retrieval problem and in the SM retrieval problem (with [T.sub.hh] and [T.sub.vv] measured in the full-polarimetric mode), the performance of the retrieval algorithms tested is not significantly altered if the model parameters are not exactly known, but are left as adjustable parameters in the optimization process. Index Terms--Aperture synthesis, L-band, ocean salinity, radiometry, retrieval, soil moisture.
- Published
- 2005
17. MIRAS end-to-end calibration: application to SMOS L1 processor
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Corbella, Ignasi, Torres, Francesc, Camps, Adriano, Colliander, Andreas, Martin-Neira, Manuel, Ribo, Serni, Rautiainen, Kimmo, Duffo, Nuria, and Vall-llossera, Merce
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Remote sensing -- Research ,Radiation -- Measurement ,Radiation -- Research ,Algorithms ,Algorithm ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
End-to-end calibration of the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) radiometer refers to processing the measured raw data up to dual-polarization brightness temperature maps over the earth's surface, which is the level 1 product of the Soil Moisture and Ocean Salinity (SMOS) mission. The process starts with a self-correction of comparators offset and quadrature error and is followed by the calibration procedure itself. This one is based on periodically injecting correlated and uncorrelated noise to all receivers in order to measure their relevant parameters, which are then used to correct the raw data. This can deal with most of the errors associated with the receivers hut does not correct for antenna errors, which must be included in the image reconstruction algorithm. Relative S-parameters of the noise injection network and of the input switch are needed as additional data, whereas the whole process is independent of the exact value of the noise source power and of the distribution network physical temperature. On the other hand, the approach relies on having at least one very well-calibrated reference receiver, which is implemented as a noise injection radiometer. The result is the calibrated visibility function, which is inverted by the image reconstruction algorithm to get the brightness temperature as a function of the director cosines at the antenna reference plane. The final step is a coordinate rotation to obtain the horizontal and vertical brightness temperature maps over the earth. The procedures presented are validated using a complete SMOS simulator previously developed by the authors. Index Terms--Calibration, data processing, image reconstruction, microwave radiometry, synthetic aperture imaging.
- Published
- 2005
18. SMOS REFLEX 2003: L-Band emissivity characterization of vineyards
- Author
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Vall-llossera, Merce, Camps, Adriano, Corbella, Ignasi, Torres, Francesc, Duffo, Nuria, Monerris, Alessandra, Sabia, Roberto, Selva, Daniel, Antolin, Carmen, Lopez-Baeza, Ernesto, Ferrer, Joan Ferran, and Saleh, Kauzar
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Vineyards -- Research ,Remote sensing -- Research ,Ocean -- Research ,Soils -- Research ,Algorithms -- Technology application ,Radiation -- Measurement ,Radiation -- Research ,Algorithm ,Technology application ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
The goal of the Soil Moisture and Ocean Salinity mission over land is to infer surface soil moisture from multiangular L-band radiometric measurements. As the canopy affects the microwave emission of land, it is necessary to characterize different vegetation layers. This paper presents the Reference Pixel L-Band Experiment (REFLEX), carried out in June-July 2003 at the Valencia Anchor Station, Spain, to study the effects of grapevines on the soil emission and on the soil moisture retrieval. A wide range of soil moisture (SM), from saturated to completely dry soil, was measured with the Universitat Politecnica de Catalunya's L-band Automatic Radiometer (LAURA). Concurrently with the radiometric measurements, the gravimetric soil moisture, temperature, and roughness were measured, and the vines were fully characterized. The opacity and albedo of the vineyard have been estimated and found to be independent on the polarization. The [tau]--[omega] model has been used to retrieve the SM and the vegetation parameters, obtaining a good accuracy for incidence angles up to 55[degrees]. Algorithms with a three-parameter optimization (SM, albedo albedo, and opacity) exhibit a better performance than those with one-parameter optimization (SM). Index Terms--L-band microwave radiometry, soil moisture, vineyards.
- Published
- 2005
19. The emissivity of foam-covered water surface at L-band: theoretical modeling and experimental results from the frog 2003 field experiment
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Camps, Adriano, Vall-llossera, Merce, Villarino, Ramon, Reul, Nicolas, Chapron, Bertrand, Corbella, Ignasi, Duffo, Nuria, Torres, Frances, Miranda, Jorge Jose, Sabia, Roberto, Monerris, Alessandra, and Rodriguez, Ruben
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Salinity -- Measurement ,Microwave devices -- Usage ,Radiation -- Measurement ,Radiation -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
Sea surface salinity can be measured by microwave radiometry at L-band (1400-1427 MHz). This frequency is a compromise between sensitivity to the salinity, small atmospheric perturbation, and reasonable pixel resolution. The description of the ocean emission depends on two main factors: 1) the sea water permittivity, which is a function of salinity, temperature, and frequency, and 2) the sea surface state, which depends on the wind-induced wave spectrum, swell, and rain-induced roughness spectrum, and by the foam coverage and its emissivity. This study presents a simplified two-layer emission model for foam-covered water and the results of a controlled experiment to measure the foam emissivity as a function of salinity, foam thickness, incidence angle, and polarization. Experimental results are presented, 37 psu salt water the foam-induced emissivity increase is ~0.007 per millimeter of foam thickness (extrapolated to nadir), increasing with increasing incidence angles at vertical polarization, and decreasing with increasing incidence angles at horizontal polarization. Index Term--Brightness temperature, emission, foam, microwave radiometry, salinity, sea.
- Published
- 2005
20. Technology Developments for an Advanced L-Band Radiometer Mission
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Martin-Neira, Manuel, primary, Suess, Martin, additional, Karafolas, Nikos, additional, Piironen, Petri, additional, Deborgies, Francois, additional, Catalan, Albert, additional, Vilaseca, Roger, additional, Montero, Jose, additional, Puertolas, Montserrat, additional, Outumuro, Diego, additional, Corbella, Ignasi, additional, Duran, Israel, additional, Duffo, Nuria, additional, Materni, Roberto, additional, Mengual, Teresa, additional, Piqueras, Miguel Angel, additional, Olea, Ana, additional, Solana, Andres, additional, Closa, Josep, additional, Zurita, Albert, additional, Ramirez, Juan Ignacio, additional, Breinbjerg, Olav, additional, Bjorstorp, Jeppe Majlund, additional, Kaslis, Kyriakos, additional, Kristensen, Steen S., additional, Oliva, Roger, additional, Onrubia, Raul, additional, Camps, Adriano, additional, and Querol, Jorge, additional
- Published
- 2020
- Full Text
- View/download PDF
21. The visibility function in interferometric aperture synthesis radiometry
- Author
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Corbella, Ignasi, Duffo, Nuria, Vall-Ilossera, Merce, Camps, Adriano, and Torres, Francesc
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Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
The fundamental equation of interferometric aperture synthesis radiometry is revised to include full antenna pattern characterization and receivers' interaction. It is shown that the cross correlation between the output signals of a pair of receivers is a Fourier-like integral of the difference between the scene brightness temperature and the physical temperature of the receivers. The derivation is performed using a thermodynamic approach to account for the effects of mutual coupling between antenna elements. The analysis assumes that the receivers include ferrite isolators so that the noise wave passing from the receiver toward the antenna can be modeled as uncorrelated ambient noise. The effect of wide beamwidth antennas on the polarization basis of the retrieved brightness temperature is also discussed. Index Terms--Interferometric aperture synthesis, microwave radiometry.
- Published
- 2004
22. Sun effects in 2-D aperture synthesis radiometry imaging and their cancelation
- Author
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Camps, Adriano, Vall-llossera, Merce, Duffo, Nuria, Zapata, M., Corbella, Ignasi, Torres, Francesc, and Barrena, V.
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Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
The Microwave Imaging Radiometer by Aperture Synthesis (MIRAS) is the single payload of the European Space Agency's (ESA) Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Opportunity mission. MIRAS will be the first two-dimensional aperture synthesis radiometer for earth observation. Two-dimensional aperture synthesis radiometers can generate brightness temperature images by a Fourier synthesis process without mechanical antenna steering. To do so and have the necessary wide swath for earth observation, the array is formed by small and low directive antennas, which do not attenuate enough bright noise sources that may interfere with the measurements. This study analyzes the impact of the radio-frequency emission from the sun in the SMOS mission, reviews the basic image reconstruction algorithms, and proposes a technique to minimize sun effects. Index Terms--Antenna arrays, imaging, interferometry, radiometry.
- Published
- 2004
23. The WISE 2000 and 2001 field experiments in support of the SMOS mission: sea surface L-band brightness temperature observations and their application to sea surface salinity retrieval
- Author
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Camps, Adriano, Font, Jordi, Vall-llossera, Merce, Gabarro, Carolina, Corbella, Ignasi, Duffo, Nuria, Torres, Francesc, Blanch, Sebastian, Aguasca, Albert, Villarino, Ramon, Enrique, Luis, Miranda, Jorge Jose, Arenas, Juan Jose, Julia, Agusti, Etcheto, Jacqueline, Caselles, Vicente, Weill, Alain, Boutin, Jacqueline, Contardo, Stephanie, Niclos, Raquel, Rivas, Raul, Reising, Steven C., Wursteisen, P., Berger, Michael, and Martin-Neira, Manuel
- Subjects
Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
Soil Moisture and Ocean Salinity (SMOS) is an Earth Explorer Opportunity Mission from the European Space Agency with a launch date in 2007. Its goal is to produce global maps of soil moisture and ocean salinity variables for climatic studies using a new dual-polarization L-band (1400-1427 MHz) radiometer Microwave Imaging Radiometer by Aperture Synthesis (MIRAS). SMOS will have multiangular observation capability and can be optionally operated in full-polarimetric mode. At this frequency the sensitivity of the brightness temperature ([T.sub.B]) to the sea surface salinity (SSS) is low: 0.5 K/psu for a sea surface temperature (SST) of 20[degrees]C, decreasing to 0.25 K/psu for a SST of 0[degrees]C. Since other variables than SSS influence the [T.sub.B] signal (sea surface temperature, surface roughness and foam), the accuracy of the SSS measurement will degrade unless these effects are properly accounted for. The main objective of the ESA-sponsored Wind and Salinity Experiment (WISE) field experiments has been the improvement of our understanding of the sea state effects on [T.sub.B] at different incidence angles and polarizations. This understanding will help to develop and improve sea surface emissivity models to be used in the SMOS SSS retrieval algorithms. This paper summarizes the main results of the WISE field experiments on sea surface emissivity at L-band and its application to a performance study of multiangular sea surface salinity retrieval algorithms. The processing of the data reveals a sensitivity of [T.sub.B] to wind speed extrapolated at nadir of ~0.23-0.25 K/(m/s), increasing at horizonal (H) polarization up to ~0.5 K/(m/s), and decreasing at vertical (V) polarization down to ~-0.2 K/(m/s) at 65[degrees] incidence angle. The sensitivity of [T.sub.B] to significant wave height extrapolated to nadir is ~1 K/m, increasing at H-polarization up to ~1.5 K/m, and decreasing at V-polarization down to -0.5 K/m at 65[degrees]. A modulation of the instantaneous brightness temperature [T.sub.B](t) is found to be correlated with the measured sea surface slope spectra. Peaks in [T.sub.B](t) are due to foam, which has allowed estimates of the foam brightness temperature and, taking into account the fractional foam coverage, the foam impact on the sea surface brightness temperature. It is suspected that a small azimuthal modulation ~0.2-0.3 K exists for low to moderate wind speeds. However, much larger values (4-5 K peak-to-peak) were registered during a strong storm, which could be due to increased foam. These sensitivities are satisfactorily compared to numerical models, and multiangular [T.sub.B] data have been successfully used to retrieve sea surface salinity. Index Terms--Foam, L-band, radiometry, sea salinity retrieval, sea spectrum, waves, wind.
- Published
- 2004
24. Sea state effect on the sea surface emissivity at L-band
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Miranda, Jorge Jose, Vall-llossera, Merce, Camps, Adriano, Duffo, Nuria, Corbella, Ignasi, and Etcheto, Jacqueline
- Subjects
Soils -- Research ,Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
In May 1999, the European Space Agency (ESA) selected the Earth Explorer Opportunity Soil Moisture and Ocean Salinity (SMOS) mission to obtain global and frequent soil moisture and ocean salinity maps. SMOS single payload is the Microwave Imaging Radiometer by Aperture Synthesis (MIRAS), an L-band two-dimensional aperture synthesis radiometer with multiangular observation capabilities. At L-band, the brightness temperature sensitivity to the sea surface salinity (SSS) is low, approximately 0.5 K/psu at 20 [degrees]C, decreasing to 0.25 K/psu at 0 [degrees]C, comparable to that to the wind speed ~ 0.2 K/(m/s) at nadir. However, at a given time, the sea state does not depend only on local winds, but on the local wind history and the presence of waves traveling from far distances. The Wnd and Salinity Experiment (WISE) 2000 and 2001 campaigns were sponsored by ESA to determine the impact of oceanographic and atmospheric variables on the L-band brightness temperature at vertical and horizontal polarizations. This paper presents the results of the analysis of three nonstationary sea state conditions: growing and decreasing sea, and the presence of swell. Measured sea surface spectra are compared with the theoretical ones, computed using the instantaneous wind speed. Differences can be minimized using an 'effective wind speed' that makes the theoretical spectrum best match the measured one. The impact on the predicted brightness temperatures is then assessed using the small slope approximation/small perturbation method (SSA/SPM). Index Terms--Nonstationary sea conditions, sea surface emissivity at L-band, sea surface spectrum, swell effect.
- Published
- 2003
25. A calibration method for fully polarimetric microwave radiometers
- Author
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Lahtinen, Janne, Gasiewski, A.J., Klein, Marian, and Corbella, Ignasi S.
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Polariscope -- Maintenance and repair ,Calibration -- Methods ,Radiometers -- Maintenance and repair ,Microwave detectors -- Maintenance and repair ,Dielectric devices -- Maintenance and repair ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
A technique for absolute end-to-end calibration of a fully polarimetric microwave radiometer is presented. The technique is based on the tripolarimetric calibration technique of Gasiewski and Kunkee, but is extended to provide a means of calibrating all four Stokes parameters. The extension is facilitated using a biaxial phase-retarding microwave plate to provide a precisely known fourth Stokes signal from the Gasiewski-Kunkee (GK) linearly polarized standard. The relations needed to determine the Stokes vector produced by the augmented standard are presented, and the effects of nonidealities in the various components are discussed. The application of the extended standard to determining the complete set of radiometer constants (the calibration matrix elements) for the National Oceanic and Atmospheric Administration Polarimetric Scanning Radiometer in a laboratory environment is illustrated. A calibration matrix inversion technique and error analysis are described, as well. The uncertainties associated with practical implementation of the fully polarimetric standard for spaceborne wind vector measurements are discussed relative to error thresholds anticipated for wind vector retrieval from the U.S. National Polar-Orbiting Environmental Satellite System. Index Terms--Calibration, dielectric devices, error analysis, microwave radiometry, polarimetry, remote sensing, wind.
- Published
- 2003
26. On-board accurate calibration of dual-channel radiometers using internal and external references
- Author
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Corbella, Ignasi, Gasiewski, Albin J., Klein, Marian, Leuski, Vladimir, Francavilla, Anthony J., and Piepmeier, Jeffrey R.
- Subjects
Microwaves -- Research ,Radiation -- Measurement ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
This paper presents a method for combining internal noise injection and external reference standard looks to accurately calibrate an airborne dual-channel radiometer. The method allows real-time estimation of the correct values of the radiometer gains and offsets, even for nontemperature-stabilized radiometers and with minimum loss of measurement time spent in external load measurement. Crosstalk and leakage introduced by the noise injection circuitry is also taken into account, thus providing high gain and offset estimation accuracy. The method was implemented on a National Oceanic and Atmospheric Administration airborne instrument, the Polarimetric Scanning Radiometer, which was used to obtain an extensive set of radiometric measurements over oceanic convection during CAMEX3 in August-September 1998. Index Terms--Calibration, radiometry.
- Published
- 2002
27. SMOS Third Mission Reprocessing after 10 Years in Orbit
- Author
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Oliva, Roger, primary, Martín-Neira, Manuel, additional, Corbella, Ignasi, additional, Closa, Josep, additional, Zurita, Albert, additional, Cabot, François, additional, Khazaal, Ali, additional, Richaume, Philippe, additional, Kainulainen, Juha, additional, Barbosa, Jose, additional, Lopes, Gonçalo, additional, Tenerelli, Joseph, additional, Díez-García, Raul, additional, González-Gambau, Veronica, additional, and Crapolicchio, Raffaele, additional
- Published
- 2020
- Full Text
- View/download PDF
28. Deriving VTEC Maps from SMOS Radiometric Data
- Author
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Rubino, Roselena, primary, Duffo, Nuria, additional, González-Gambau, Verónica, additional, Corbella, Ignasi, additional, Torres, Francesc, additional, Durán, Israel, additional, and Martín-Neira, Manuel, additional
- Published
- 2020
- Full Text
- View/download PDF
29. One-Point Microwave Radiometer Calibration
- Author
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Corbella, Ignasi, primary, Torres, Francesc, additional, Closa, Josep, additional, Duffo, Nuria, additional, Duran, Israel, additional, Gonzalez-Gambau, Veronica, additional, and Martin-Neira, Manuel, additional
- Published
- 2020
- Full Text
- View/download PDF
30. Toward an Enhanced SMOS Level-2 Ocean Salinity Product
- Author
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Olmedo, Estrella, primary, Gonzalez-Gambau, Veronica, additional, Turiel, Antonio, additional, Guimbard, Sebastien, additional, Gonzalez-Haro, Cristina, additional, Martinez, Justino, additional, Gabarro, Carolina, additional, Portabella, Marcos, additional, Arias, Manuel, additional, Sabia, Roberto, additional, Oliva, Roger, additional, and Corbella, Ignasi, additional
- Published
- 2020
- Full Text
- View/download PDF
31. Radiometric sensitivity computation in aperture synthesis interferometric radiometry
- Author
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Camps, Adriano, Corbella, Ignasi, Bara, Javier, and Torres, Francis
- Subjects
Radiometers -- Evaluation ,Interferometry -- Research ,Remote sensing -- Research ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
This paper is concerned with the radiometric sensitivity computation of an aperture synthesis interferometric radiometer devoted to earth observation. The impact of system parameters and the use of simultaneous redundant measurements are analyzed. The Interferometric Radiometer Uncertainty Principle is presented; it quantifies the relationship between radiometric sensitivity and angular resolution. Index Terms - Interferometry, radiometry, remote sensing, sensitivity.
- Published
- 1998
32. Instantaneous model of a MESFET for use in linear and nonlinear circuit simulations
- Author
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Corbella, Ignasi, Legido, Josep Maria, and Naval, Gonzalo
- Subjects
Field-effect transistors -- Models ,Simulation methods -- Research ,Computer simulation -- Research ,Integrated circuits -- Models ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
A formal approach for nonlinear modeling of FET's is presented. The intrinsic transistor is described by current and charge generators, that are instantaneously dependent on the two internal voltages. The extrinsic parasitic elements are also included. This instantaneous model is obtained from the small signal equivalent circuit computed at a number of bias points, by integration of the bias dependent elements. A program for using this model in nonlinear circuit analysis has been developed. The process has been carried out for two transistors, one being of low noise, and the other a power MESFET. Good agreement has been observed when comparing the nonlinear analysis with measured data. Finally a Solid State Power Amplifier at 28 GHz has been designed using the power transistor, delivering 21 dBm at 1 dB compression point.
- Published
- 1992
33. SMOS Instrument Performance after More than 9 Years in Orbit
- Author
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Martin-Neira, Manuel, primary, Cabot, Francois, additional, Khazaal, Ali, additional, Anterrieu, Eric, additional, Richaume, Philippe, additional, Barbosa, Jose, additional, Lopes, Goncalo, additional, Tenerelli, Joe, additional, Diez-Garcia, Raul, additional, Fauste, Jorge, additional, Turiel, Antonio, additional, Oliva, Roger, additional, Gonzalez-Gambau, Veronica, additional, Crapolicchio, Raffaele, additional, Macelloni, Giovanni, additional, Brogioni, Marco, additional, Vogel, Pierre, additional, Suess, Martin, additional, Corbella, Ignasi, additional, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, Kainulainen, Juha, additional, Closa, Josep, additional, and Zurita, Albert, additional
- Published
- 2019
- Full Text
- View/download PDF
34. MIRAS Temporal Stability
- Author
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Corbella, Ignasi, primary, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, Gonzalez-Gambau, Veronica, additional, Oliva, Roger, additional, and Martin-Neira, Manuel, additional
- Published
- 2019
- Full Text
- View/download PDF
35. Calibration of the MIRAS Radiometers
- Author
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Corbella, Ignasi, primary, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, Gonzalez-Gambau, Veronica, additional, Oliva, Roger, additional, Closa, Josep, additional, and Martin-Neira, Manuel, additional
- Published
- 2019
- Full Text
- View/download PDF
36. De campañas de medidas a productos de salinidad: un tributo a las contribuciones de Jordi Font a la mision SMOS
- Author
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Camps, Adriano, Gabarró, Carolina, Vall-llossera, Mercè, Blanch, Sebastià, Aguasca, Albert, Torres, Francesc, Corbella, Ignasi, Duffo, Nuria, Turiel, Antonio, Portabella, Marcos, Ballabrera-Poy, Joaquim, González-Gambau, Verónica, Martínez, Justino, Villarino, Ramón, Enrique, Luís, Monerris, Alessandra, Bosch, Xavier, Sabia, Roberto, Talone, Marco, Piles, Maria, Pablos, Míriam, Valencia, Enric, and This work has been performed under research grants TEC2005-06863-C02-01/TCM, ESP2005-06823-C05 and ESP2007-65667-C04, AYA2008-05906-C02-01/ ESP, AYA2010-22062-C05 and ESP2015-70014-C2- 1-R, and EURYI 2004 award
- Subjects
SMOS ,radiometría ,interferometría ,calibración ,validación ,salinidad ,humedad del terreno ,hielo marino ,GNSS-R ,radiometry ,interferometry ,calibration ,validation ,salinity ,soil moisture ,sea ice - Abstract
This article summarizes some of the activities in which Jordi Font, research professor and head of the Department of Physical and Technological Oceanography, Institut de Ciències del Mar (CSIC, Spanish National Research Council) in Barcelona, has been involved as co-Principal Investigator for Ocean Salinity of the European Space Agency Soil Moisture and Ocean Salinity (SMOS) Earth Explorer Mission from the perspective of the Remote Sensing Lab at the Universitat Politècnica de Catalunya. We have probably left out some of his many contributions to salinity remote sensing, but we hope that this review will give an idea of the importance of his work. We focus on the following issues: 1) the new accurate measurements of the sea water dielectric constant, 2) the WISE and EuroSTARRS field experiments that helped to define the geophysical model function relating brightness temperature to sea state, 3) the FROG 2003 field experiment that helped to understand the emission of sea foam, 4) GNSS-R techniques for improving sea surface salinity retrieval, 5) instrument characterization campaigns, and 6) the operational implementation of the Processing Centre of Levels 3 and 4 at the SMOS Barcelona Expert Centre., Este artículo resume algunas de las actividades en las que Jordi Font, profesor de investigación y jefe del Departamento de Física y Tecnología Oceanográfica, del Institut de Ciències del Mar (CSIC) en Barcelona, ha estado desarrollando como co-Investigador Principal de la parte de la misión SMOS de la ESA, una misión Earth Explorer, desde la perspectiva del Remote Sensing Lab, de la Universitat Politècnica de Catalunya. Seguramente, estamos olvidando algunas de sus muchas contribuciones a la teledetección de la salinidad, pero esperamos que esta revisión dé una idea de la importancia de su trabajo. Este artículo se focaliza en los siguientes puntos: 1) las medidas de alta calidad de la constante dieléctrica del agua marina, 2) las campañas de medidas WISE y EuroSTARRS que ayudaron a la definición del modelo geofísico relacionando la temperatura de brillo con el estado del mar, 3) la campaña de medidas FROG 2003 que ayudó a entender la emisión de la espuma marina 4) presentación de las técnicas de GNSS-R para la mejora de la recuperación de la salinidad superficial 5) campañas para la caracterización del instrumento y 6) la implantación del centro de procesado operacional de niveles 3 y 4 en el SMOS Barcelona Expert Centre.
- Published
- 2016
- Full Text
- View/download PDF
37. Smos Instrument Performance After More Than 8 Years in Orbit and Lessons Learnt for Future L-Band Missions
- Author
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Martin-Neira, Manuel, primary, Suess, Martin, additional, Oliva, Roger, additional, Fauste, Jorge, additional, Corbella, Ignasi, additional, Torres, Francese, additional, Duffo, Nuria, additional, Duran, Israel, additional, Kainulainen, Juha, additional, Closa, Josep, additional, Zurita, Alberto, additional, Cabot, Francois, additional, Khazaal, Ali, additional, Anterrieu, Eric, additional, Barbosa, Jose, additional, Lopes, Goncalo, additional, Tenerelli, Joe, additional, Diez-Garcia, Raul, additional, Turiel, Antonio, additional, Gonzalez-Gambau, Veronica, additional, and Crapolicchio, Raffaele, additional
- Published
- 2018
- Full Text
- View/download PDF
38. Self-Consistent Amplitude Calibration of Miras-SMOS
- Author
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Corbella, Ignasi, primary, Torres, Francese, additional, Duffo, Nuria, additional, Duran, Israel, additional, Oliva, Roger, additional, and Martin-Neira, Manuel, additional
- Published
- 2018
- Full Text
- View/download PDF
39. Lessons learnt from SMOS after 7 years in orbit
- Author
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Martin-Neira, Manuel, primary, Oliva, Roger, additional, Corbella, Ignasi, additional, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, Kainulainen, Juha, additional, Closa, Josep, additional, Zurita, Alberto, additional, Cabot, Francois, additional, Khazaal, Ali, additional, Anterrieu, Eric, additional, Barbosa, Jose, additional, Lopes, Goncalo, additional, Tenerelli, Joe, additional, Diez-Garcia, Raul, additional, Fauste, Jorge, additional, Gonzalez-Gambau, Veronica, additional, Turiel, Antonio, additional, Delwart, Steven, additional, Crapolicchio, Raffaele, additional, Suess, Martin, additional, Mecklenburg, Susanne, additional, Drusch, Matthias, additional, Sabia, Roberto, additional, Daganzo-Eusebio, Elena, additional, Kerr, Yann, additional, and Reul, Nicolas, additional
- Published
- 2017
- Full Text
- View/download PDF
40. From field experiments to salinity products: a tribute to the contributions of Jordi Font to the SMOS mission
- Author
-
Camps, Adriano, primary, Gabarró, Carolina, additional, Vall-llossera, Mercè, additional, Blanch, Sebastià, additional, Aguasca, Albert, additional, Torres, Francesc, additional, Corbella, Ignasi, additional, Duffo, Nuria, additional, Turiel, Antonio, additional, Portabella, Marcos, additional, Ballabrera-Poy, Joaquim, additional, González-Gambau, Verónica, additional, Martínez, Justino, additional, Villarino, Ramón, additional, Enrique, Luís, additional, Monerris, Alessandra, additional, Bosch, Xavier, additional, Sabia, Roberto, additional, Talone, Marco, additional, Piles, Maria, additional, Pablos, Míriam, additional, and Valencia, Enric, additional
- Published
- 2016
- Full Text
- View/download PDF
41. The Correlation of Visibilty Noise and Its Impact on the Radiometric Resolution of an Aperture Synthesis Radiometer
- Author
-
Bara, Javier, Camps, Adriano, Torres, Francesc, and Corbella, Ignasi
- Subjects
Microwave receivers -- Usage ,Synthetic aperture radar -- Image quality ,Radiation -- Measurement ,Earth sciences -- Remote sensing ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
The correlation between the visibility samples' noise of an aperture synthesis radiometer are required for the computation of the recovered temperature noise of a given pixel and of the improvement introduced by baseline redundance. A general expression for this correlation and noise examples for a linear array are presented. Index Terms--Microwave radiometry, microwave receivers, radio interferometry, radiometry, remote sensing, synthetic aperture imaging.
- Published
- 2000
42. Analysis of Noise-Injection Networks for Interferometric-Radiometer Calibration
- Author
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Corbella, Ignasi, Camps, Adriano, Torres, Francesc, and Bara, Javier
- Subjects
Radiation -- Measurement ,Interferometry -- Research ,Business ,Computers ,Electronics ,Electronics and electrical industries - Abstract
The spatial resolution of current space-borne Earth observation radiometers is limited by the physical antenna aperture. This is especially critical at L-band, which exhibits high sensitivity to soil moisture and sea surface salinity. Interferometric radiometers (InR's) are currently being studied by several space agencies as a feasible alternative to overcome this problem. However, their calibration is a crucial issue since most techniques inherited from radio astronomy cannot be directly applied. Due to the large number of receiving channels, calibration techniques based on centralized noise injection from a single noise source will require a large and stable distribution network, which is technically very complex and unacceptable from the point-of-view of mass and volume. Procedures based on distributed noise injection from a set of noise sources through smaller distribution networks have been recently proposed by the authors as an alternative to alleviate these technological problems. In this paper, the analysis of these networks, the impact of the noise generated by the network losses on the calibration, and the impact of front-end reradiated noise are analyzed. Finally, the optimum circuit topologies and tolerances to which these networks have to be characterized in order to achieve the required calibration are derived. These configurations are formed by cascading basic 1:2 and 1:3 isolated power splitters. Isolators at receivers' inputs have to be included in order to minimize offsets originated from the correlation of reradiation of receiver noise. It has been found that, in order to satisfy the calibration requirements of InR's, the S-parameters of the ensemble noise-injection network plus isolators have to be known to within 0.025-0.050 dB in amplitude and 0.5 [degrees] in phase, and their physical temperature known to within 0.5 [degrees] C. Index Terms--Calibration, interferometry, noisy networks, radiometry.
- Published
- 2000
43. RF Interference Analysis in Aperture Synthesis Interferometric Radiometers: Application to L-Band MIRAS Instrument
- Author
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Camps, Adriano J., Corbella, Ignasi, Torres, Francesc, Bara, Javier, and Capdevila, Joan
- Subjects
Remote sensing -- Equipment and supplies ,Radiometers -- Equipment and supplies ,Interferometry -- Equipment and supplies ,Business ,Earth sciences ,Electronics and electrical industries - Abstract
Current spaceborne radiometers do not achieve the required spatial resolution demanded by the scientific community due to antenna-size technological limitations. In recent years, several space agencies have been studying aperture synthesis interferometric radiometers as a way of overcoming these limitations, which are more evident at low microwave frequencies (e.g., at L-band), where sea surface salinity and soil moisture can be monitored. Interference is an important issue in any remote sensing instrument, but it is crucial in microwave radiometers, since the signal being measured is the spontaneous thermal noise emission. Interference analyses already exist for classic radiometers. The objective of this paper is the analysis of RF interference on interferometric radiometers. The study involves the analysis of possible interference sources that may affect the performance of such systems at L-band: 1) nearby emissions from radars, non-Geo-Stationary Orbit (GSO) and Mobile Satellite Services (GSO-MSS), 2) harmonics of lower frequency emissions, and 3) possible jamming. Index Terms--Interference, interferometry, radiometry, remote sensing.
- Published
- 2000
44. SMOS instrument performance and calibration after 6 years in orbit
- Author
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Martin-Neira, Manuel, primary, Oliva, Roger, additional, Corbella, Ignasi, additional, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, Kainulainen, Juha, additional, Closa, Josep, additional, Zurita, Alberto, additional, Cabot, Francois, additional, Khazaal, Ali, additional, Anterrieu, Eric, additional, Barbosa, Jose, additional, Lopes, Goncalo, additional, Tenerelli, Joe, additional, Diez-Garcia, Raul, additional, Fauste, Jorge, additional, Gonzdlez-Gambau, Veronica, additional, Turiel, Antonio, additional, Delwart, Steven, additional, Crapoticchio, Raffaele, additional, and Suess, Martin, additional
- Published
- 2016
- Full Text
- View/download PDF
45. The MIRAS “all-licef” calibration mode
- Author
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Corbella, Ignasi, primary, Gonzalez-Gambau, Veronica, additional, Torres, Francesc, additional, Duffo, Nuria, additional, Duran, Israel, additional, and Martin-Neira, Manuel, additional
- Published
- 2016
- Full Text
- View/download PDF
46. SMOS simplified iterative full-pol brightness temperature retrieval
- Author
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Duran, Israel, primary, Lin, Wu, additional, Torres, Francesc, additional, Corbella, Ignasi, additional, Duffo, Nuria, additional, and Martin-Neira, Manuel, additional
- Published
- 2016
- Full Text
- View/download PDF
47. Impact of antenna tuning on SMOS correlation loss
- Author
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Torres, Francesc, primary, Duran, Israel, additional, Corbella, Ignasi, additional, Duffo, Nuria, additional, Closa, Josep, additional, Oliva, Roger, additional, and Martin-Neira, Manuel, additional
- Published
- 2016
- Full Text
- View/download PDF
48. Mitigation of cross-polar antenna pattern errors in SMOS: Simplified approach
- Author
-
Duran, Israel, primary, Torres, Francesc, additional, Corbella, Ignasi, additional, Duffo, Nuria, additional, Wu, Lin, additional, and Martin-Neira, Manuel, additional
- Published
- 2016
- Full Text
- View/download PDF
49. Impact of amplitude calibration errors on SMOS global images
- Author
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Durare, Israel, primary, Corbella, Ignasi, additional, Torres, Francesc, additional, Duffo, Nuria, additional, Oliva, Roger, additional, and Martin-Neira, Manuel, additional
- Published
- 2016
- Full Text
- View/download PDF
50. Nodal Sampling: A New Image Reconstruction Algorithm for SMOS
- Author
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Gonzalez-Gambau, Veronica, primary, Turiel, Antonio, additional, Olmedo, Estrella, additional, Martinez, Justino, additional, Corbella, Ignasi, additional, and Camps, Adriano, additional
- Published
- 2016
- Full Text
- View/download PDF
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