Design, implementation and verification of CubeSat systems for Earth Observation

In recent years, Earth Observation (EO) technologies have surged in an attempt to better understand the world we live in, and exploit the vast amount of data that can be collected to improve our lives. The field of EO encompasses a broad array of technologies capable of extracting information remotely, in a process called Remote Sensing (RS). CubeSats are causing a revolution in the RS field, and are becoming a really important contribution to it. The lack of testing and preparation are common in CubeSat EO missions due to the low budgets they usually suffer from. A successful CubeSat EO mission must supply the lack of size or funding with properly tested components and environments. In this document, emphasis will be given to preemptive approaches such as studying the performance of Commercial Off-The-Shelf (COTS) Global Positioning System (GPS) receivers and the development of simulators for highly dynamic environments This topic will be expanded upon by introducing the problematic of simulating such signals for testing, and the possible countermeasures to Radio-Frequency Interference (RFI) that threatens the success of the mission. Finally, a new S-Band Ground Station will be built to provide access to this band for future CubeSat missions. All of the above will provide a holistic view on some of the hot challenges that EO faces, and multiple future research paths that open with the recent rise of New Space technologies

A review of RFI mitigation techniques in microwave radiometry

Radio frequency interference (RFI) is a well-known problem in microwave radiometry (MWR). Any undesired signal overlapping the MWR protected frequency bands introduces a bias in the measurements, which can corrupt the retrieved geophysical parameters. This paper presents a literature review of RFI detection and mitigation techniques for microwave radiometry from space. The reviewed techniques are divided between real aperture and aperture synthesis. A discussion and assessment of the application of RFI mitigation techniques is presented for each type of radiometer.Peer ReviewedPostprint (published version

Montsec Ground Station

In every space mission, the ability to contact the satellite to transmit or receive telecommands and data is one of the critical parts, so having a good ground segment is fundamental. In support to 3Cat-2 operations a ground station was first developed by the UPC NanoSat Lab at UPC Campus Nord premises. However, due to increasing radio frequency interference it was moved to the Institute Space Studies of Catalonia (IEEC) - Observatori del Montsec (OdM), located in Sant Esteve de la Sarga, Lleida. This location has outstanding reception conditions in terms of very weak interference levels, and excellent elevation mask (i.e. satellites can be tracked even below the horizon). The ground station is equipped with a TX/RX Yagi antenna for amateur bands VHF (144-146 MHz) and UHF (435-438 MHz), and it also includes an S-band 3-meter dish in the commercial band (2025-2110 MHz, 2200-2290 MHz) for reception that will be upgraded for transmission in 2022. The antenna rotors, receivers etc. are remotely controlled to the operation-center in Barcelona and operations can be automated. Nowadays, the ground station is jointly operated by the UPC NanoSat Lab and the IEEC in support to the Catalan New Space strategy, in addition to the upcoming UPC missions

Analysis on the feasability of airborne GNSS-R receivers for weather nowcasting and target detection

Weather forecast relies to a large extent on data acquired by satellite. LEO polar satellites provide global coverage, but poor spatial resolution. GEO satellites provide a better coverage and revisit time, at expenses of poorer spatial resolution. LEO constellations of small satellites offer the promise of global coverage with good spatial resolution and revisit time. However, hosted payloads on aircrafts offer the potential of very high resolution and very low revisit time for regional applications. In this work, the idea of equipping commercial airliners with low-cost Global Navigation Satellite System - Reflectometer (GNSS-R) receivers is explored, with emphasis on real-world data and the implications the expected scientific yield would offer.This work has received funding from project Spanish Ministerio de Ciencia, Innovacion y Universidades and EU ERDF project ref. RTI2018-099008-B-C21 ”SENSING WITH PIONEERING OPPORTUNISTIC TECHNIQUES,“ , and support grant MDM-2016-0600 to “María de Maeztu Excellence Units” CommSensLab, from Spanish Ministerio de Economía y Competitividad (MINECO/FEDER).Peer ReviewedPostprint (published version

FSSCat Mission description and first scientific results of the FMPL-2 onboard 3CAT-5/A

FSSCat, the “Federated Satellite Systems/ 3 Cat-5” mission was the winner of the 2017 ESA S^3 (Sentinel Small Satellite) Challenge and overall winner of the Copernicus Masters competition. FSSCat consists of two 6 unit cubesats carrying on board UPC's Flexible Microwave Payload - 2 (FMPL-2), an L-band microwave radiometer and GNSS-Reflectometer implemented in a software defined radio, and Cosine's HyperScout-2 visible and near infrared + thermal infrared hyperspectral imager, enhanced with PhiSat-1, a on board Artificial intelligence experiment for cloud detection. Both spacecrafts include optical and UHF inter-satellite links technology demonstrators, provided by Golbriak Space and UPC, respectively. This paper describes the mission, and the main scientific results of the FMPL-2 obtained during the first three months of the mission, notably the sea ice concentration and thickness, and the downscaled soil moisture products over the Northern hemisphere.This work was supported by 2017 ESA S 3 challenge and Copernicus Masters overall winner award (“FSSCat” project) and ESA project “FSSCat Validation Experiment in MOSAIC”, by the Spanish Ministry of Science, Innovation and Universities, "Sensing with Pioneering Opportunistic Techniques" SPOT, grant RTI2018-099008- BC21/AEI/10.13039/501100011033, and by the Unidad de Excelencia Maria de Maeztu MDM-2016-0600.Peer ReviewedArticle signat per 25 autors/es: A. Camps 1,2; J.F. Munoz‐Martin 1; J.A. Ruiz‐de‐Azua 1,2; L. Fernandez 1; A. Perez-Portero 1; D. Llavería 1; C. Herbert 1; M. Pablos 3; A. Golkar 4,1; A. Gutiérrrez 5; C. António 5; J. Bandeiras 5; J. Andrade 5; D. Cordeiro 5; S. Briatore 4,6; N. Garzaniti 4,6; F. Nichele 7; R. Mozzillo 7; A. Piumatti 7; M. Cardi 7; M. Esposito 8; B. Carnicero Dominguez 9; M. Pastena 9; G. Filippazzo 10; A. Reagan 10 // 1. Universitat Politècnica de Catalunya, Barcelona, Spain; 2. Institut d’Estudis Espacials de Catalunya, Barcelona, Spain; 3. Institut de Ciències del Mar (ICM-CSIC) & Barcelona Expert Center (BEC) on Remote Sensing, Barcelona, Spain; 4. Skolkovo Institute of Science and Technology, Moscow, Russia; 5. Deimos Eng., Lisbon, Portugal; 6. Golbriak Space, Tallin, Estonia; 7. Tyvak International, Torino, Italy; 8. Cosine, Oosteinde, The Netherlands; 9. ESA ESTEC, Noordwijk, The Netherlands; 10. ESA ESRIN, Frascati, ItalyPostprint (author's final draft

A pre-correlation RFI mitigation algorithm for L-band interferometric radiometers

Radio Frequency Interference (RFI) is a major concern for both real and synthetic aperture radiometers. After the lessons learnt from SMOS, ESA is preparing the next generation of L-band interferometric radiometers with RFI mitigation integrated into the cross-correlators. This work presents a preliminary design and results of a pre-correlation RFI mitigation algorithm tailored for interferometric radiometers. The results show that the correlation error introduced by the RFI is reduced on average to the half, with peaks of 20 dB of mitigation.Peer ReviewedPostprint (author's final draft

RFI detection and mitigation for advanced correlators in interferometric radiometers

This work presents the first RFI detection and mitigation algorithm for the interferometric radiometers that will be implemented in its correlator unit. The algorithm operates in the time and frequency domains, applying polarimetric and statistical tests in both domains, and exhibiting a tunable and arbitrary low probability of false alarm. It is scalable to a configurable number of receivers, and it is optimized in terms of quantization bits and the implementation of the cross-correlations in the time or frequency domains for hardware resource saving. New features of this algorithm are the computation of the Stokes parameters per frequency bin in the Short-Time Fourier Transform and a new parameter called Polarimetric Kurtosis. If RFI is detected in one domain or in both, it is removed using the calculated blanking masks. The optimum algorithm parameters are computed, such as length of the FFTs, the threshold selection for a given probability of false alarm, and the selection of the blanking masks. Last, an important result refers to the application of Parseval’s theorem for the computation of the cross-correlations in the frequency domain, instead of in the time domain, which is more efficient and leads to smaller errors even when using moderate quantization levels. The algorithm has been developed in the framework of the ESA’s technology preparation for a potential L-band radiometer mission beyond SMOS. However, it is also applicable to (polarimetric) real aperture radiometers, and its performance would improve if more than one bit is used in the signal quantization.This research was funded by ESA, grant number ITT AO9359, by project SPOT: Sensing with Pioneering Opportunistic Techniques grant RTI2018-099008-B-C21/AEI/10.13039/501100011033, and the grant for recruitment of early stage research staff of the Agència de Gestió d’Ajuts Universitaris i de Recerca (AGAUR) Generalitat de Catalunya, Spain (FISDUR2020/105).Peer ReviewedPostprint (published version

RITA: a 1U multi-sensor Earth observation payload for the AlainSat-1

The Remote sensing and Interference detector with radiomeTry and vegetation Analysis (RITA) is one of the Remote Sensing payloads selected as winners of the 2nd GRSS Student Grand Challenge in 2019, to fly on board of the 3U AlainSat-1. This CubeSat is being developed by the National Space Science and Technology Center (NSSTC), United Arab Emirates University. RITA has been designed as an academic mission, which brings together students from different backgrounds in a joint effort to apply very distinct sensors in an Earth Observation mission, fusing their results to obtain higher-accuracy measurements. The main payload used in RITA is a Total Power Radiometer such as the one on board the FSSCat mission. With these radiometric measurements, soil moisture and ice thickness will be obtained. To better characterize the extensive Radio-Frequency Interferences received by EO satellites in protected bands, several RFI Detection and Classification algorithms will be included to generate a worldwide map of RFI. As a novel addition to the 3Cat family of satellites and payloads, a hyper-spectral camera with 25 bands ranging from 600 to 975 nm will be used to obtain several indexes related to vegetation. By linking these measurements with the soil moisture obtained from the MWR, pixel downscaling can be attempted. Finally, a custom- developed LoRa transceiver will be included to provide a multi-level approach to in-situ sensors: On-demand executions of the other payloads will be able to be triggered from ground sensors if necessary, as well as simple reception of other measurements that will complement the ones obtained on the satellite. The antennas for both the MWR and the LoRa experiments have been developed in-house, and will span the entirety of one of the 3U sides of the satellite. In this work, the latest development advances will be presented, together with an updated system overview and information about the operations that will be conducted. Results obtained from the test campaign are also presented in the conference

Labour and social security law in Spain in 2015

El informe ha sido elaborado por la Sección Juvenil de la Asociación Española de Derecho del Trabajo y Seguridad SocialEste Informe deja constancia de los cambios normativos más relevantes y de las tendencias judiciales más paradigmáticas del ordenamiento laboral en 2015. En él se observa el imparable dinamismo del Derecho del Trabajo y de la Seguridad Social en España. El documento, consciente de tal mutabilidad, recoge una minuciosa selección de cuestiones esenciales, a juicio de las personas que abordan cada una de las materias, de las que son especialistas; los autores y las autoras, que forman parte de la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social, se adscriben a los grupos temáticos por afinidad con sus principales líneas de investigación y su labor docente universitaria. En síntesis, en el Informe “El Derecho del Trabajo y de la Seguridad Social en España en 2015” se puede encontrar información muy útil para los profesionales del iuslaboralismo en materia de derechos fundamentales inespecíficos, contratación laboral y empleo, vicisitudes del contrato de trabajo, derechos colectivos, igualdad y corresponsabilidad, Seguridad Social o prevención de riesgos laborales.This report has as aim leaving a record of the most relevant normative changes and the most paradigmatic judicial trends in Labour Law in 2015. One can easily observe the unstoppable dynamismof Labour and Social Security Law in Spain. The document, conscious of that mutability, collects a thorough selection of key issues, according to the judgement of the authors, all of them specialists and all of them members of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. They are part of thematic groups, linked to their main research lines and their teaching task. Summing up, in this report “Labour and Social Security Law in Spain in 2015”, one can easily find useful information for labour lawyers in subjects such as unspecific fundamental rights, work contracts and employment, issues of the labour relationship, collective rights, equality and co-responsibility, Social Security or occupational risk prevention

El Derecho del Trabajo y de la Seguridad Social en España en 2015. Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social.

Este Informe deja constancia de los cambios normativos más relevantes y de las tendencias judiciales más paradigmáticas del ordenamiento laboral en 2015. En él se observa el imparable dinamismo del Derecho del Trabajo y de la Seguridad Social en España. El documento, consciente de tal mutabilidad, recoge una minuciosa selección de cuestiones esenciales, a juicio de las personas que abordan cada una de las materias, de las que son especialistas; los autores y las autoras, que forman parte de la Sección Juvenil de la Asociación Española de Derecho del Trabajo y de la Seguridad Social, se adscriben a los grupos temáticos por afinidad con sus principales líneas de investigación y su labor docente universitaria. En síntesis, en el Informe “El Derecho del Trabajo y de la Seguridad Social en España en 2015” se puede encontrar información muy útil para los profesionales del iuslaboralismo en materia de derechos fundamentales inespecíficos, contratación laboral y empleo, vicisitudes del contrato de trabajo, derechos colectivos, igualdad y corresponsabilidad, Seguridad Social o prevención de riesgos laborales. This report has as aim leaving a record of the most relevant normative changes and the most paradigmatic judicial trends in Labour Law in 2015. One can easily observe the unstoppable dynamismof Labour and Social Security Law in Spain. The document, conscious of that mutability, collects a thorough selection of key issues, according to the judgement of the authors, all of them specialists and all of them members of the Young Scholars’ Section of the Spanish Association for Labour and Social Security Law. They are part of thematic groups, linked to their main research lines and their teaching task. Summing up, in this report “Labour and Social Security Law in Spain in 2015”, one can easily find useful information for labour lawyers in subjects such as unspecific fundamental rights, work contracts and employment, issues of the labour relationship, collective rights, equality and co-responsibility, Social Security or occupational risk prevention