http://hdl.handle.net/2117/654 Fri, 24 May 2013 02:11:40 GMT 2013-05-24T02:11:40Z webmaster.bupc@upc.edu Universitat Politècnica de Catalunya. Servei de Biblioteques i Documentació no http://hdl.handle.net/2117/19340 Title: Stability of the MIRAS amplitude calibration Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. Fri, 17 May 2013 13:43:19 GMT http://hdl.handle.net/2117/19340 2013-05-17T13:43:19Z Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín Neira, Manuel no Radiometer calibration, Accurate modeling, Amplitude calibration, Antenna temperature, Internal calibration, Radiometer calibration, Receiver front-ends Efficient methods to characterize and mitigate long-and short- term drifts in SMOS data have been developed after careful analysis of the external and internal calibration parameters and by accurate modeling of the individual receiver front-ends. A method to characterize this drift has been successfully developed and used to reduce the measured antenna temperature variations. http://hdl.handle.net/2117/19326 Title: Performance of a spatial error correction technique in SMOS brightness temperature images Authors: Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel Abstract: Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. Fri, 17 May 2013 10:19:57 GMT http://hdl.handle.net/2117/19326 2013-05-17T10:19:57Z Wu, Lin; Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín Neira, Manuel no Performance of a spatial error correction technique in SMOS brightness temperature images Soil Moisture and Ocean Salinity (SMOS) brightness temperature synthesized images are obtained after a comprehensive calibration and error correction procedure. However, the final images are still contaminated by small but non-negligible spatial errors: the so-called pixel bias. These errors have been found to be very stable in the SMOS Alias-Free Field of View (AF-FoV) and can be mitigated, to a large extent, by applying a multiplicative mask to the measured brightness temperatures at the antenna plane. This paper describes the procedure to upgrade this mask to cover SMOS Extended AF­ FoV. http://hdl.handle.net/2117/18273 Title: An OFDMA-PON with non-preselected independent ONU sources and centralized feedback wavelength control: Dimensioning and experimental results Authors: Cano Valadéz, Iván Nicolás; Santos Blanco, M. Concepción; Escayola Elias, Francisco Javier; Polo Querol, Víctor; Giacoumidis, E.; Kachris, C.; Tomkos, Ioannis; Prat Gomà, Josep Joan Abstract: A simple and low cost method for wavelength control based on centralized OLT monitoring and feedback of economical random non-preselected independent ONU sources is presented. The technique was dimensioned and experimentally tested in an OFDMA-PON with 1 Gb/s ONUs and 30 km of fibre along with the minimum optical spectral gap between consecutive ONU wavelengths. Results indicate that this method reduces the spectral overlap probability and increasing the number of users and cost-effectiveness of a PON, Wed, 13 Mar 2013 15:52:48 GMT http://hdl.handle.net/2117/18273 2013-03-13T15:52:48Z Cano Valadéz, Iván Nicolás; Santos Blanco, M. Concepción; Escayola Elias, Francisco Javier; Polo Querol, Víctor; Giacoumidis, E.; Kachris, C.; Tomkos, Ioannis; Prat Gomà, Josep Joan no A simple and low cost method for wavelength control based on centralized OLT monitoring and feedback of economical random non-preselected independent ONU sources is presented. The technique was dimensioned and experimentally tested in an OFDMA-PON with 1 Gb/s ONUs and 30 km of fibre along with the minimum optical spectral gap between consecutive ONU wavelengths. Results indicate that this method reduces the spectral overlap probability and increasing the number of users and cost-effectiveness of a PON, http://hdl.handle.net/2117/18217 Title: Conmutadores RF-MEMS de baja tensión Authors: Contreras Lizarraga, Adrián Arturo; Casals Terré, Jasmina; Pradell i Cara, Lluís; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel; Giacomozzi, Flavio Abstract: This work shows experimental results of capacitive and ohmic RF-MEMS switches with low actuation voltage. The isolation of capacitive switches is better than 20 dB from 15 GHz and up to 80 GHz according to simulations. The ohmic-contact switch can be used in coplanar waveguide (CPW) reconfigurable multimodal circuits, for a selective use of the CPW odd-mode. The CPW odd-mode isolation in the down state is better than 20 dB up to 8 GHz and better than 10 dB up to 30 GHz. Tue, 12 Mar 2013 14:45:03 GMT http://hdl.handle.net/2117/18217 2013-03-12T14:45:03Z Contreras Lizarraga, Adrián Arturo; Casals Terré, Jasmina; Pradell i Cara, Lluís; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel; Giacomozzi, Flavio no This work shows experimental results of capacitive and ohmic RF-MEMS switches with low actuation voltage. The isolation of capacitive switches is better than 20 dB from 15 GHz and up to 80 GHz according to simulations. The ohmic-contact switch can be used in coplanar waveguide (CPW) reconfigurable multimodal circuits, for a selective use of the CPW odd-mode. The CPW odd-mode isolation in the down state is better than 20 dB up to 8 GHz and better than 10 dB up to 30 GHz. http://hdl.handle.net/2117/17950 Title: Low voltage capacitive and Ohmic RF-MEMS Switches Authors: Contreras Lizarraga, Adrián Arturo; Casals Terré, Jasmina; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel Abstract: This work presents experimental results of capacitive and ohmic-contact RF-MEMS switches. The suspension has been designed to compensate stress-gradient effects, and to obtain low pull-in voltages. The measured actuation voltage is 12 V for devices with an air gap of 1.3 µm. The measured isolation of the capacitive switches is better than 20 dB for frequencies above 15 GHz, and better than 30 dB from 31 GHz up to 80 GHz according to simulations. The ohmic-contact switch can be used to control the odd mode in coplanar waveguide (CPW) reconfigurable multimodal circuits. The CPW odd-mode isolation of the ohmic-contact switch in its down state is better than 20 dB up to 8 GHz and better than 10 dB up to 30 GHz. Fri, 22 Feb 2013 15:49:08 GMT http://hdl.handle.net/2117/17950 2013-02-22T15:49:08Z Contreras Lizarraga, Adrián Arturo; Casals Terré, Jasmina; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel no This work presents experimental results of capacitive and ohmic-contact RF-MEMS switches. The suspension has been designed to compensate stress-gradient effects, and to obtain low pull-in voltages. The measured actuation voltage is 12 V for devices with an air gap of 1.3 µm. The measured isolation of the capacitive switches is better than 20 dB for frequencies above 15 GHz, and better than 30 dB from 31 GHz up to 80 GHz according to simulations. The ohmic-contact switch can be used to control the odd mode in coplanar waveguide (CPW) reconfigurable multimodal circuits. The CPW odd-mode isolation of the ohmic-contact switch in its down state is better than 20 dB up to 8 GHz and better than 10 dB up to 30 GHz. http://hdl.handle.net/2117/17868 Title: A RF-MEMS switchable CPW air-bridge Authors: Contreras, Adrián; Casals Terré, Jasmina; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel Abstract: This work presents a new shunt-type ohmic contact RF-MEMS switch specifically designed as a switchable CPW air bridge. The switch can be used in coplanar waveguide (CPW) reconfigurable multimodal circuits, for a selective use of the CPW odd-mode. The bridge is anchored using folded-beam suspensions, in such a way that two points at each end of the bridge remain free to contact the ground planes of the CPW. The suspension has been designed to compensate stress gradients effects and to lower actuation voltage. In the actuated (ON) state, the switch isolation to the odd mode is better than 20dB up to 8GHz and 10dB up to 30GHz. Tue, 19 Feb 2013 09:39:00 GMT http://hdl.handle.net/2117/17868 2013-02-19T09:39:00Z Contreras, Adrián; Casals Terré, Jasmina; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina; Iannacci, Jacopo; Ribó, Miquel no This work presents a new shunt-type ohmic contact RF-MEMS switch specifically designed as a switchable CPW air bridge. The switch can be used in coplanar waveguide (CPW) reconfigurable multimodal circuits, for a selective use of the CPW odd-mode. The bridge is anchored using folded-beam suspensions, in such a way that two points at each end of the bridge remain free to contact the ground planes of the CPW. The suspension has been designed to compensate stress gradients effects and to lower actuation voltage. In the actuated (ON) state, the switch isolation to the odd mode is better than 20dB up to 8GHz and 10dB up to 30GHz. http://hdl.handle.net/2117/17867 Title: Filtro paso-banda con control preciso de frecuencia central y ancho de banda usando interruptores RF MEMS Authors: Brito Brito, Zabdiel; Llamas Garro, Ignacio; Perruisseau Carrier, Julien; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina Abstract: In this paper a reconfigurable bandpass filter is presented. The filter is able to switch between two different states with a center frequency tunable range of 24 % in C band. Center frequency and bandwidth are precisely met by a switchable filter topology that includes two folded resonator extensions switched by four ohmic-contact cantilever-type Micro Electro Mechanical Systems (MEMS) switches. The filter was designed to have center frequencies of 5 and 6.2 GHz, with a fractional bandwidth of 7 and 3 %, respectively. The filter was fabricated on a quartz substrate and measured responses are in good agreement with simulations. Filter specifications were successfully met with the proposed topology. Tue, 19 Feb 2013 09:26:19 GMT http://hdl.handle.net/2117/17867 2013-02-19T09:26:19Z Brito Brito, Zabdiel; Llamas Garro, Ignacio; Perruisseau Carrier, Julien; Pradell i Cara, Lluís; Giacomozzi, Flavio; Colpo, Sabrina no In this paper a reconfigurable bandpass filter is presented. The filter is able to switch between two different states with a center frequency tunable range of 24 % in C band. Center frequency and bandwidth are precisely met by a switchable filter topology that includes two folded resonator extensions switched by four ohmic-contact cantilever-type Micro Electro Mechanical Systems (MEMS) switches. The filter was designed to have center frequencies of 5 and 6.2 GHz, with a fractional bandwidth of 7 and 3 %, respectively. The filter was fabricated on a quartz substrate and measured responses are in good agreement with simulations. Filter specifications were successfully met with the proposed topology. http://hdl.handle.net/2117/17332 Title: SMOS payload pre-launch performance Authors: Martín-Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; González-Gambau, Verónica; Colliander, A; Closa, Josep; Benito, J; Borges, A; Brown, M; McMullan, K Mon, 14 Jan 2013 12:35:48 GMT http://hdl.handle.net/2117/17332 2013-01-14T12:35:48Z Martín-Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; González-Gambau, Verónica; Colliander, A; Closa, Josep; Benito, J; Borges, A; Brown, M; McMullan, K no http://hdl.handle.net/2117/17329 Title: MIRAS characterization and monitoring during the SMOS In-Orbit Commissioning Phase Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Martín-Neira, Manuel; Duffo Ubeda, Núria; González-Gambau, Verónica; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena Mon, 14 Jan 2013 12:06:35 GMT http://hdl.handle.net/2117/17329 2013-01-14T12:06:35Z Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Martín-Neira, Manuel; Duffo Ubeda, Núria; González-Gambau, Verónica; Camps Carmona, Adriano José; Vall-Llossera Ferran, Mercedes Magdalena no http://hdl.handle.net/2117/17324 Title: SMOS payload in-orbit performance Authors: Martín-Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; González-Gambau, Verónica; Closa, Josep; Benito, Javier; Borges, A.; Rautiainen, K.; Kainulainen, J.; Gutierrez, A.; Barbosa, J.; Catarino, N.; Castro, R.; Freitas, S.; Candeias, H.; Freitas, J.; Cabot, F.; Anterrieu, E.; Zundo, M.; Brown, M.; McMullan, K.; Martín-Porqueras, F.; Oliva, R.; Wright, N.; Caprolicchio, R. Mon, 14 Jan 2013 11:10:04 GMT http://hdl.handle.net/2117/17324 2013-01-14T11:10:04Z Martín-Neira, Manuel; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; González-Gambau, Verónica; Closa, Josep; Benito, Javier; Borges, A.; Rautiainen, K.; Kainulainen, J.; Gutierrez, A.; Barbosa, J.; Catarino, N.; Castro, R.; Freitas, S.; Candeias, H.; Freitas, J.; Cabot, F.; Anterrieu, E.; Zundo, M.; Brown, M.; McMullan, K.; Martín-Porqueras, F.; Oliva, R.; Wright, N.; Caprolicchio, R. no http://hdl.handle.net/2117/16498 Title: Physical layer evaluation of OFDM-based access networks Authors: Cano Valadez, Ivan; Santos Blanco, M. Concepción; Prat Gomà, Josep Joan; Krimmel, H.G.; Kavatzikidis, T.; Giacoumidis, E.; Tomkos, Ioannis Abstract: In this paper, we present a physical layer parameter optimization of direct-detection optical OFDM techniques at bitrates of 10 Gb/s and 40 Gb/s using an intensity modulation and two types of field modulation transmitters: optical IQ modulator and frequency up-conversion. The performance of these schemes is evaluated and compared for access networks. Fri, 14 Sep 2012 11:35:58 GMT http://hdl.handle.net/2117/16498 2012-09-14T11:35:58Z Cano Valadez, Ivan; Santos Blanco, M. Concepción; Prat Gomà, Josep Joan; Krimmel, H.G.; Kavatzikidis, T.; Giacoumidis, E.; Tomkos, Ioannis no In this paper, we present a physical layer parameter optimization of direct-detection optical OFDM techniques at bitrates of 10 Gb/s and 40 Gb/s using an intensity modulation and two types of field modulation transmitters: optical IQ modulator and frequency up-conversion. The performance of these schemes is evaluated and compared for access networks. http://hdl.handle.net/2117/16089 Title: Interferometric radiometry measurement concept: The visibility equation Authors: Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín-Neira, Manuel Abstract: 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 are briefly summarized. Examples of real measurements from the sensor onboard the ESA SMOS mission are used to illustrate the image reconstruction techniques. Mon, 18 Jun 2012 16:22:31 GMT http://hdl.handle.net/2117/16089 2012-06-18T16:22:31Z Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín-Neira, Manuel no 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 are briefly summarized. Examples of real measurements from the sensor onboard the ESA SMOS mission are used to illustrate the image reconstruction techniques. http://hdl.handle.net/2117/16086 Title: Phase error assessment of MIRAS/SMOS by means of the redundant space calibration Authors: Dávila, Rubén; Torres Torres, Francisco; Duffo Ubeda, Núria; Corbella Sanahuja, Ignasi; Pablos, Miriam; Martín-Neira, Manuel Abstract: SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was successfully launched in November 2009. A six months Commissioning Phase was devoted to bring the satellite into a fully operational condition and to characterize the payload using specific orbits to check all instrument modes [2]. An ongoing activity is devoted to analyze the contribution of each single calibration procedure to the overall radiometric accuracy in order to assess the dominant sources of spatial errors. In this framework, this paper is devoted to assess the performance of the phase calibration procedures by means of the so called Redundant Space Calibration (RSC)1. Mon, 18 Jun 2012 15:07:24 GMT http://hdl.handle.net/2117/16086 2012-06-18T15:07:24Z Dávila, Rubén; Torres Torres, Francisco; Duffo Ubeda, Núria; Corbella Sanahuja, Ignasi; Pablos, Miriam; Martín-Neira, Manuel no SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was successfully launched in November 2009. A six months Commissioning Phase was devoted to bring the satellite into a fully operational condition and to characterize the payload using specific orbits to check all instrument modes [2]. An ongoing activity is devoted to analyze the contribution of each single calibration procedure to the overall radiometric accuracy in order to assess the dominant sources of spatial errors. In this framework, this paper is devoted to assess the performance of the phase calibration procedures by means of the so called Redundant Space Calibration (RSC)1. http://hdl.handle.net/2117/16085 Title: Correction of spatial errors in SMOS brightness temperature images Authors: Wu, Lin; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín-Neira, Manuel Abstract: Systematic spatial errors in SMOS brightness temperature images are successfully estimated by using a statistical analysis of measured data. A constant multiplicative mask is derived by averaging spatial errors of a large number of snapshots over the ocean. The mask has been obtained for the aliasfree field of view region without the need of any geophysical model. It can be considered as part of the instrument characterization and is totally independent of the target to measure. When this mask is applied to regular SMOS brightness temperatures, the spatial artifacts are clearly reduced. Mon, 18 Jun 2012 15:01:06 GMT http://hdl.handle.net/2117/16085 2012-06-18T15:01:06Z Wu, Lin; Corbella Sanahuja, Ignasi; Torres Torres, Francisco; Duffo Ubeda, Núria; Martín-Neira, Manuel no Systematic spatial errors in SMOS brightness temperature images are successfully estimated by using a statistical analysis of measured data. A constant multiplicative mask is derived by averaging spatial errors of a large number of snapshots over the ocean. The mask has been obtained for the aliasfree field of view region without the need of any geophysical model. It can be considered as part of the instrument characterization and is totally independent of the target to measure. When this mask is applied to regular SMOS brightness temperatures, the spatial artifacts are clearly reduced. http://hdl.handle.net/2117/14818 Title: SMOS brightness temperature measurements and end-to-end calibration Authors: Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín-Neira, Manuel Abstract: SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was launched in November 2009. After a six months Commissioning Phase SMOS entered in operational mode in May 2010. Since then SMOS has been delivering a large amount of data to successfully produce the first relevant scientific results. In order to provide accurate measurements, MIRAS requires a complex multi-step calibration procedure that was successfully tested both during pre-flight ground tests and Commissioning Phase activities. Additionally, an assessment of SMOS system performance in terms of short and long term stability, radiometric sensitivity and radiometric accuracy was also produced. In this context, this work is devoted to provide a high level overview of MIRAS calibration scheme by focusing on the rationale behind it. Wed, 25 Jan 2012 19:21:29 GMT http://hdl.handle.net/2117/14818 2012-01-25T19:21:29Z Torres Torres, Francisco; Corbella Sanahuja, Ignasi; Duffo Ubeda, Núria; Martín-Neira, Manuel no SMOS is the acronym for the Soil Moisture and Ocean Salinity mission by the European Space Agency (ESA) [1]. Its single payload, the Microwave Imaging Radiometer using Aperture Synthesis (MIRAS), was launched in November 2009. After a six months Commissioning Phase SMOS entered in operational mode in May 2010. Since then SMOS has been delivering a large amount of data to successfully produce the first relevant scientific results. In order to provide accurate measurements, MIRAS requires a complex multi-step calibration procedure that was successfully tested both during pre-flight ground tests and Commissioning Phase activities. Additionally, an assessment of SMOS system performance in terms of short and long term stability, radiometric sensitivity and radiometric accuracy was also produced. In this context, this work is devoted to provide a high level overview of MIRAS calibration scheme by focusing on the rationale behind it.