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The integration of non-terrestrial networks into the 5G ecosystem is mainly driven by the possibility of provisioning service in remote areas. In this context, the advent of flying base stations at the low Earth orbit (LEO) will enable anywhere and anytime connectivity. To materialize this vision, it is of utmost importance to improve radio protocols with the aim of allowing direct satellite access. Bearing this aspect in mind, we present a new random access signal, which is based on the filter bank multicarrier (FBMC) waveform, and a computationally efficient detection scheme. The proposed solution outperforms the standardized access scheme based on single-carrier frequency division multiplexing (SC-FDM), by reducing out-of-band (OOB) emissions and reducing the missed detection probability in presence of very high carrier frequency offset (CFO), which is inherent to LEO satellite systems. The improvement is related to the fine frequency resolution of the detector and the use of pulse shaping techniques. Interestingly, the FBMC-based random access signal achieves a high level of commonality with 5G new radio, as the preamble generation method and the time-frequency allocation pattern can be kept unchanged. Concerning the practical implementation aspects, the complexity of the detector is similar in both SC-FDM and FBMC. This paper is part of the R+D+i project (PID2020-115323RB-C31) funded by MCIN/AEI/ 10.13039/501100011033. This work is supported by the grant from Spanish Ministry of Economic Affairs and Digital Transformation and the European union - NextGenerationEU (UNICO-5G I+D/AROMA3D-Space (TSI-063000-2021-70))

The objective of this bachelors thesis is to conduct a comprehensive analysis of the communication subsystems in the UHF, S, and X bands of the 3Cat-8 mission. This mission aims to develop a satellite under the CubeSat standard that allows the study of different physical phenomena, such as the effects of auroral emissions on wave propagation through the ionosphere. Furthermore, this project also includes the design of an S-band patch antenna, both to understand the design of a space application antenna and to implement it on the same satellite and compare it with other commercial options. In addition, the polar orbit described by the satellite results in limited opportunities for data downlink, making it necessary to design and dimension magnetic actuators to enable the satellite to point towards the ground station. This document addresses the study, design, and manufacturing of these elements in order to enable the satellite to aim its antennas at the ground station. Overall, this work represents a significant contribution to the 3Cat-8 mission. Throughout this project, various activities encompassing the fields of aerospace engineering and telecommunications have been carried out.

This Final Degree Project aims at developing a telecommunications link using LoRa technology to interconnect a PocketQube (pico-satellites with a form factor of 5 x 5 x 5 cm^3) with a ground station from the TinyGS network. This long-range low-bandwidth link can be used to download the telemetry, the payload or the configuration data, and to send telecommands from the ground station to the PocketQube, such as the execution of orders as activate the payload, do a soft reset, perform an ADCS calibration etc. In this Final Degre Project, the communication protocols will be implemented, using COTS LoRa TTGO T-Display ESP32 WiFi module (Arduino based), and a PocketQube developed at the UPC NanoSat Lab, which uses an STM 32 (to be programmed in C-language) as On-Board Computer. Objectius de Desenvolupament Sostenible::15 - Vida d'Ecosistemes Terrestres

Due to an increasing entry barrier to both universities and researchers in conventional small satellites initiatives, there has been an emergence of smaller and cheaper spacecrafts like PocketQubes, a much more affordable option for public entities. Considering all that, this thesis has been developed as part of a project undertaken by the UPC NanoSat Lab which started as an IEEE GRSS initiative named PoCat. The objective of the PoCat project is to design, develop and test three single unit picosatellites with each featuring the following different payloads, a Video Graphics Array (VGA) camera, a Radio Frequency Interference (RFI) monitoring system at L-band and an RFI monitoring system at K-Band. The three satellites, however, contain the same avionics core composed of the On-Board Computer (OBC), Communication System (COMMS), Attitude Determination and Control System (ADCS) and Electrical Power Supply System (EPS). Given this scenario, the purpose of this report is to give insights regarding the on-board software development for PocketQubes, which as of writing this report there is still room for debate concerning their standardization. Conceptually, the OBC system acts as the brain of the satellite. As for the technology, the OBC is build upon the STM32L476 microcontroller due to its memory storage, power efficiency and processing power. Performing the power management as well as giving response to events are the main objectives of the OBC. In order to do the latter, the flight software is based on a Real-Time Operating System (RTOS) called FreeRTOS which has been selected above other Operating System (OS) due to its predictability, compliance with the required deadlines, support, available documentation, compatibility with previous projects, licensing costs, and certifications. According to FreeRTOS, the program is structured into independent tasks where each one features a priority in line with their criticality. Then, the project is constituted by eight tasks, with five designed to operate the subsystems of the satellite, one for memory writing purposes and the remaining two are devoted to implement FreeRTOS software timers. Furthermore, tasks can communicate with each other by means of task notifications or event groups, both being software tools provided by the operating system.

Existing climatological ionosphere models, for example, GISM, SCIONAV, WBMOD, and STIPEE, have known limitations that prevent their wide use. In the framework of ESA study “Radio Climatology Models of the Ionosphere: Status and Way Forward” their performance was assessed using experimental observations of ionospheric scintillation collected over the past years to evaluate their ability to properly support future missions, and eventually indicate their weaknesses for future improvements. Model limitations are more important in terms of the intensity scintillation parameter (S4). To improve them, the COSMIC model has been fit (scaling factor and offset) to the measured data, and it became the one better predicting the intensity scintillation in a statistical sense. This research was funded by the project “Radio Climatology Models of the Ionosphere: Status and Way Forward,” ESA/ESTEC, grant number 4000120868/17/NL/AF [https://nebula.esa.int/content/radio-climatology-models-ionosphere-status-and-way-forward]. Article processing charges were funded by the project “GENESIS: GNSS Environmental and Societal Missions – Subproject UPC,” AEI Grant PID2021-126436OB-C21.

The ability to enhance the spatial resolution of measurements collected by a conical-scanning microwave radiometer (MWR) is discussed in terms of noise amplification and improvement of the spatial resolution. Simulated (and actual) brightness temperature profiles are analyzed at variance of different intrinsic spatial resolutions and adjacent beams overlapping modeling a simplified 1-D measurement configuration (MC). The actual measurements refer to Special Sensor Microwave Imager (SSM/I) data collected using the 19.35 and the 37.00 GHz channels that match the simulated configurations. The reconstruction of the brightness profile at enhanced spatial resolution is performed using an iterative gradient method which allows a fine tuning of the level of regularization. Objective metrics are introduced to quantify the enhancement of the spatial resolution and noise amplification. Numerical experiments, performed using the simplified 1-D MC, show that the regularized deconvolution results in negligible advantages when dealing with low-overlapping/fine-spatial-resolution configurations. Regularization is a mandatory step when addressing the high-overlapping/low-spatial-resolution case and the spatial resolution can be enhanced up to 2.34 with a noise amplification equal to 1.56. A more stringent requirement on the noise amplification (up to 0.6) results in an improvement of the spatial resolution up to 1.64.

This paper presents an integrated network architecture combining a cell-free massive multiple-input multiple-output (CF-M-MIMO) terrestrial layout with a low Earth orbit satellite segment where the scalability of the terrestrial segment is taken into account. The main purpose of such an integrated scheme is to transfer to the satellite segment those users that somehow limit the performance of the terrestrial network. Towards this end, a correspondingly scalable technique is proposed to govern the ground-to-satellite user diversion that can be tuned to different performance metrics. In particular, in this work the proposed technique is configured to result in an heuristic that improves the minimum per-user rate and the sum-rate of the overall network. Simulation results serve to identify under which conditions the satellite segment can become an attractive solution to enhance users’ performance. Generally speaking, although the availability of the satellite segment always leads to an improvement of users’ rates, it is in those cases where the terrestrial CF-M-MIMO network exhibits low densification traits that the satellite backup becomes crucial. This work was supported in part by the Agencia Estatal de Investigación, Ministerio de Ciencia e Innovación (MCIN/AEI/10.13039/501100011033) through the R+D+i Project under Grant PID2020-115323RB-C32 and Grant PID2020-115323RB-C31; and in part by the Centre Tecnológic de Telecomunicacions de Catalunya Researchers through the Grant from the Spanish Ministry of Economic Affairs and Digital Transformation and the European Union-NextGenerationEU under Grant UNICO-5G I+D/AROMA3D-Hybrid TSI-063000-2021-71.

Magnetic attitude control systems are suitable for very small satellites, and yet provide a simple and robust method to detumbling and attitude control. In this work we analyse the use of hard ferromagnetic materials and magnetorquers to control the attitude of a spherical femtosatellite. The model will propagate the orbit of the satellite (disregarding the effects of the atmosphere) by means of SGP4 or SGP8. Once the orbit is propagated, we will use a suitable model of the geomagnetic field (IGRF13 or WMM) to determine the magnetic field in the location of the satellite. Passive ADCS will be obtained by means of the use of hysteresis rods. In order to add some control, a set of magnetorquers will be designed. Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

This final degree thesis describes the development and implementation of an ADCS simulator for the 3Cat-8 mission of the UPC NanoSat Lab, which enables the calculation of the actuators and controller variables. Additionally, based on the ADCS simulator, specially focuses on the ATHENA ionic thruster control analysis ensuring the proper ADCS actuators sizing of the spacecraft. The control is solely achieved by magnetic actuators. It is shown that the satellite can maintain the desired orientation with low angular rates, required during the orbital raising maneuver. A new configuration of the control stability with linear attitude dynamics for satellite thruster, based on a control algorithm using attitude quaternion and angular velocity feedback is also described. To conclude, the presented numerical results prove the efficiency of the applied method based on initial theoretical considerations and the design measurements of the satellite and the thruster.

The development of the project has been contextualized in LEO satellite constellations and the possibilities they offer as a communications network, with particular focus on ground-to-air communications (aircraft). The initial objective of this thesis has been the research of the A* shortest path routing algorithm, trying to find heuristic models that generate competitive performance versus the optimal path routing provided by the Dijkstra algorithm. At the same time, a graphical environment has been developed in order to show the algorithm's behaviour. Secondly, another algorithm (Yen) to provide alternatives to the shortest path without necessarily considering disjoint paths has been searched and developed. To conclude, a jump into spatiotemporal domain perspective has been made, developing a methodology to establish routings that are able to provide real-time voice signals, while the delay steps through time are minimised, offering a reliable communications system. The results offer a new research framework, analysing the feasibility of the offered solutions. El desarrollo del proyecto se ha contextualizado en las redes satelitales LEO y las posibilidades que ofrecen como red de comunicaciones, con un enfoque particular en las comunicaciones tierra-aire (aviación). El objetivo inicial de esta tesis ha sido investigar el algoritmo de búsqueda de caminos A*, tratando de hallar modelos heurísticos que generen un rendimiento competitivo frente al algoritmo óptimo (Dijkstra). Al mismo tiempo, se ha desarrollado una interfaz gráfica para mostrar el funcionamiento del algoritmo. Seguidamente, se ha desarrollado otro algoritmo (Yen) para tener otra opción a considerar caminos disjuntos al óptimo como alternativa. Como conclusión, se ha hecho un salto al dominio espacio-temporal, desplegando una metodología para establecer rutas capaces de ofrecer señal de voz en tiempo real, mientras se minimizan transiciones abruptas de retardo, ofreciendo un sistema de comunicaciones fiable. Los resultados ofrecen un nuevo marco de investigación, analizando la factibilidad de las soluciones ofrecidas. El desenvolupament del projecte s'ha contextualitzat a les xarxes de satèl·lits LEO i les possibilitats que ofereixen com a xarxa de comunicacions, amb un enfocament particular en les comunicacions terra-aire (aviació). L'objectiu inicial d'aquesta tesi ha sigut el d'investigar l'algoritme de cerca de camins A*, tractant de trobar models heurístics que generin un rendiment competitiu vers l'algoritme òptim (Dijkstra). Al mateix temps, s'ha desenvolupat una interfície gràfica per mostrar el funcionament de l'algoritme. Seguidament, s'ha desenvolupat un altre algoritme (Yen) per tindre un altra opció a considerar camins disjunts a l'òptim com a alternativa. Com a conclusió, s'ha fet un salt al domini espacial-temporal, desplegant una metodologia per establir rutes capaces d'oferir senyal de veu en temps real, alhora que minimitzant transicions abruptes de retard, oferint un sistema de comunicacions fiable. Els resultats ofereixen un nou camp d'investigació, analitzant la factibilitat de les solucions oferides.

The space segment of the Global Navigation Satellite System (GNSS) is equipped with highly stable atomic clocks. In order to use these clocks as references, their time offsets must be estimated from ground measurements as accurately as possible. This work presents a multi-frequency and multi-constellation method for estimating satellite and receiver clock corrections, starting from unambiguous, uncombined, and undifferenced carrier-phase measurements. A byproduct of the estimation process is phase biases (i.e., the hardware delays of the carrier-phase measurements occurring at receivers and satellites). The stability and predictability of our clock estimates for receivers and satellites (GPS and Galileo) are compared with those obtained by the International GNSS Service (IGS), whereas the phase biases are assessed against two independent determinations involving combinations of carrier-phase measurements. We conclude that the method reduces day boundary discontinuities in the clock corrections, and that the estimated phase biases reproduce variabilities already observed by other authors. The present work was supported in part by the Euro-pean Space Agency contract (REL-GAL) N.4000122402/17/NL/IB, by the project RTI2018-094295-B-I00 funded bytheMCIN/AEI10.13039/501100011033whichisco-foundedby the FEDER programme, and by the Horizon 2020 MarieSkłodowska-Curie Individual Global Fellowship 797461NAVSCIN. The authors acknowledge the use of data andproducts provided by the International GNSS Service

This paper investigates a dual satellite transmission scheme with coherent reception. The receiver has a single synchronization circuit and is locked to only one of the satellites. Beam-centric pre-compensation techniques are considered in the paper. The cooperation area in which coherent reception is feasible is characterized analytically. The application of precoding to the orthogonal time and frequency space (OTFS) waveform is considered to counteract the residual offsets, which result from the displacement of the receiver from the selected reference point. Numerical evaluations show that the dual satellite scheme improves the system spectral efficiency as well the link reliability in comparison with the single satellite transmission scheme. This paper is part of the R+D+i project (PID2020-115323RB-C31) funded by MCIN/AEI/ 10.13039/501100011033.

The Federated Satellite Systems/ 3 Cat-5 (FSSCat) mission was the winner of the European Space Agency (ESA) Sentinel Small Satellite (S 3 ) Challenge and overall winner of the 2017 Copernicus Masters competition. It consisted of two six-unit CubeSats. The Earth observation payloads were 1) the Flexible Microwave Payload 2 (FMPL-2) onboard 3 Cat-5/A, an L-band microwave radiometer and GNSS reflectometer (GNSS-R) implemented using a software-defined radio (SDR), and 2) the HyperScout-2 onboard 3 Cat-5/B, a hyperspectral camera, with the first experiment using artificial intelligence to discard cloudy images. FSSCat was launched on 3 September 2020 and injected into a 535-km synchronous orbit. 3 Cat-5/A was operated for three months until the payload was probably damaged by a solar flare and coronal mass ejection. During this time, all scientific requirements were met, including the generation of coarse-resolution and downscaled soil moisture (SM) maps, sea ice extent (SIE) maps, concentration and thickness maps, and even wind speed (WS) and sea surface salinity (SSS) maps, which were not originally foreseen. 3 Cat-5/B was operated a few more months until the number of images acquired met the requirements. This article briefly describes the FSSCat mission and the FMPL-2 payload and summarizes the main scientific results. This work was supported by the 2017 ESA S3 challenge and Copernicus Masters overall winner award (FSSCat project) and ESA project FSSCat Validation Experiment in MOSAIC; Spanish Ministry of Science, Innovation, and Universities Sensing With Pioneering Opportunistic Techniques grant RTI2018-099008-BC21/AEI/10.13039/501100011033; GNSS Environmental and Societal Missions grant PID2021- 126436OB-C21; and Unidad de Excelencia Maria de Maeztu grant MDM-2016-0600. Peer Reviewed Article signat per 30 autors/es: Adriano Camps, Universitat Politècnica de Catalunya, Barcelona, Spain, Institut d’Estudis Espacials de Catalunya, Barcelona, Spain, United Arab Emirates University, Abu Dhabi, United Arab Emirates; Joan Francesc Munoz-Martin, Universitat Politècnica de Catalunya, Barcelona, Spain, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA; Joan Adrià Ruiz-de-Azua, Universitat Politècnica de Catalunya, Barcelona, Spain, i2Cat, The Internet Research Center, Barcelona, Spain; Lara Fernandez, Universitat Politècnica de Catalunya, Barcelona, Spain; Adrian Perez-Portero, Universitat Politècnica de Catalunya, Barcelona, Spain; David Llavería, Universitat Politècnica de Catalunya, Barcelona, Spain; Christoph Herbert, Universitat Politècnica de Catalunya, Barcelona, Spain; Miriam Pablos, Institut de Ciències del Mar, Barcelona, Spain, Barcelona Expert Center on Remote Sensing, Barcelona, Spain; Alessandro Golkar, Universitat Politècnica de Catalunya, Barcelona, Spain, Department of Aerospace and Geodesy, Technical University of Munich, Munich, Germany; Antonio Gutiérrez, Deimos Engenharia, Lisbon, Portugal; Carlos António, Deimos Engenharia, Lisbon, Portugal; Jorge Bandeiras, Deimos Engenharia, Lisbon, Portugal; Jorge Andrade, Deimos Engenharia, Lisbon, Portugal; David Cordeiro, Deimos Engenharia, Lisbon, Portugal; Simone Briatore, Golbriak Space, Tallin, Estonia; Nicola Garzaniti, Golbriak Space, Tallin, Estonia, School of Aerospace, Transport, and Manufacturing, Cranfield University, Cranfield, Bedfordshire, U.K.; Fabio Nichele, Tyvak International, Torino, Italy; Raffaele Mozzillo, Tyvak International, Torino, Italy; Alessio Piumatti, Tyvak International, Torino, Italy; Margherita Cardi, Tyvak International, Torino, Italy; Marco Esposito, Cosine, Sassenheim, The Netherlands; Chris van Dijk, Cosine, Sassenheim, The Netherlands; Nathan Vercruyssen, Cosine, Sassenheim, The Netherlands; Joao Barbosa, Cosine, Sassenheim, The Netherlands; John Hefele, Cosine, Sassenheim, The Netherlands; Rick Koeleman, Cosine, Sassenheim, The Netherlands; Bernardo Carnicero Dominguez, European Space Research and Technology Center, European Space Agency, Noordwijk, The Netherlands; Massimiliano Pastena, European Space Research and Technology Center, European Space Agency, Noordwijk, The Netherlands; Giancarlo Filippazzo, European Space Research Institute, European Space Agency, Frascati (RM), Italy; Amanda Reagan, European Space Research Institute, European Space Agency, Frascati (RM), Italy.

Ionospheric disturbances induced by seismic activity have been studied in the last years by many authors, showing an impact both before and after the occurrence of earthquakes. In this study, the ionospheric scintillation produced by the 2021 La Palma volcano eruption is analyzed. The "Cumbre Vieja" volcano was active from September 19th to December 13th, 2021, and many magnitude 3–4 earthquakes were recorded, with some of them reaching magnitude 5. In this study the three methods: GNSS reference monitoring, GNSS Reflectometry (GNSS-R) from NASA CYGNSS, and GNSS Radio Occultation (GNSS-RO) from COSMIC and Spire constellations, are used, allowing us to compare and evaluate their performance in the same conditions. To compare the seismic activity with ionospheric scintillation, earthquakes’ generated energy, and percentile 95 % of the intensity scintillation parameter (S4), measurements have been computed every 6 h intervals for the whole duration of the volcanic eruption. GNSS-RO has shown the best correlation between earthquakes’ energy and S4, with values up to 0.09 when the perturbations occur around 18 h after the seismic activity. GNSS reference monitoring stations data also shows some correlation 18 h after and 7–8 days after. As expected, GNSS-R is the one that shows the smallest correlation, as the ionospheric signatures get masked by the signature of the surface where the reflection is taking place. Additionally, as expected as well, the three methods show a smaller correlation during the week before earthquakes. This work was supported in part by the grant PID2021-126436OB-C21 from the Programa Estatal para Impulsar la Investigación Científico-Técnica y su Transferencia, del Plan Estatal de Investigación Científica, Técnica y de Innovación 2021-2023 (Spain) and in part by the European Social Fund (ESF). GNSS-RO Spire data has been provided by the European Space Agency through the ESA TPM SPIRE project id 67176.

Las comunicaciones han evolucionado de manera exponencial, gracias a los avances tecnológicos. Por este motivo, surgen nuevas formas de comunicaciones, una de ellas el IoT. Que consiste en una tecnología que facilita la recopilación de datos y da conectividad a todo tipo de elementos, como por ejemplo los utilizados en las viviendas domóticas. Este proyecto, se centrará en la utilización de un tipo de comunicación IoT, en concreto la comunicación satelital. El objetivo principal del proyecto es el diseño e implementación de la comunicación satelital utilizada en la transmisión de la información desde una boya, situada en la superficie del mar. Para conseguir está transmisión de datos se utilizará un módulo Kinéis, que estará controlado por el microcontrolador ESP32. Para la geolocalización de la boya se usará un GPS y se transmitirán otros datos, además de los obtenidos por el GPS y relacionados con características del medio marino. Estos últimos datos, se almacenarán en la tarjeta de memora para su transmisión. Todos los datos enviados al satélite se monitorizarán en una página web, de manera que pueden ser consultados en cualquier momento. Communications have evolved exponentially, thanks to technological advances. For this reason, new forms of communication are emerging, one of which is the IoT. This is a technology that easy data collection and provides connectivity to all types of elements, such as those used un automation homes. This project will focus on the use of one type of IoT communication, specifically satellite communication. The main purpose of the project is the design and implementation of the satellite communication and the transmission of information from a buoy. To archive this data transmission will be used Kinéis module, which will be controlled by the ESP32 microcontroller. A GPS will be used to geolocate the buoy. On the other hand, other data will be transmitted, apart from these obtained by the GPS, and are related to the characteristic of the marine environment. This last data will be stored on a memory card for transmission. All data sent to the satellite will be monitored on a website, so that this data can be consulted at any time.

As the title indicates, the project is divided in two parts: The first part of this document will explain the development of a LEO positioning system based on Iridium satellites. This system has been implemented in Matlab, and although different methods have been tried, the best results have been obtained with the Extended Kalman Filter. Despite this, there is still place for improvement. The second part explains the development process of a software tool for satellite observation in the form of a web app called "Satellite Tracker". Specifically it is used for orbit visualization, for LEO satellites just as the Iridium and Starlink constellations or the ISS, and also for GPS satellites. This software also allows for the observation of the Doppler effect, that is produced by the movement of the satellite, and other real-time parameters, just as the user area visibility. His goal is to be useful specially for the students of the subject of Air Navigation, Cartography and Cosmography at EETAC, and also for other students around the world. The used technologies, in the case of the frontend of the web app, are HTML, CSS, Bootstrap and Javascript, while for the backend, the framework Flask has been used which uses Python as a programming language. To store the necessary data, for the correct operation of the web app, a non-relational database such as MongoDB has been utilized. Although, some improvements have been presented on both parts of the project, good results have been obtained and the initial goals have been accomplished.

Space has been populated by a wide range of satellite systems from governmental and private space entities. Monolithic satellites have been ruling it by providing a custom design that accomplishes a specific mission. Nevertheless, novel user demands emerged have required global coverage, low revisit time, and ubiquitous service. The possibility to integrate in-orbit infrastructure to support current communications systems has been discussed persistently during the last years. Specifically, the concept of deploying networks composed of aircraft and spacecraft (creating the so-called Non-Terrestrial Networks), has emerged as a potential architecture to satisfy this new demand. This novel concept has enabled to investigate mobile technologies in space infrastructure. For example, this is the case of the Software-Defined Satellite, which aims at managing in-orbit infrastructure by using Software-Defined Network techniques. These novel concepts pose multiple challenges which dedicated developments shall address. Likewise, specific equipment and simulation environments shall support them. Currently, open source satellite network emulators have certain limitations or are not easily accessible. This project aims at presenting the Virtual Satellite Network Simulator, a novel simulation engine capable to represent satellites as well as ground nodes in virtual machines and deploy a virtual network that depicts the channel effects and dynamics. VSNeS has been generated from different modules, that thanks to the joint work is able to generate the virtualization. First of all, a Python3 program has been developed, which works as a manager and is responsible for running the rest of the modules according to the virtualized scenario. Furthermore, Kernel-based Virtual Machine has been implemented for the execution of the virtual machines. The channel management is done with the NetEm emulator. Finally, a graphical user interface is delivered by Cesium. This dissertation presents formally a preliminary design with the essential steps to select each technology. Then, the networking design is also discussed. Different tests are also shown in order to verify the correct functioning of the tool. In addition, tests about the performance of the final release have been performed. The program has been tested with the following protocols in different realistic scenarios: TCP, UDP, and ICMP. This allowed us to verify the correct operation of the program, checking the delays and channel losses. Moreover, it is empirically demonstrated that some protocols are not functional for geostationary satellites, due to the long latency caused by the large distances.

OPS-SAT is an ESA technology demonstration cubesat which includes a colour camera, a Software Defined Radio (SDR) receiver and a powerful ARM processor. One of the experiments executed there is FAPEC, a high-performance and versatile data compression software. Among others, it features image compression and linear prediction coding algorithms, suitable for multi-band and baseband radio-frequency (RF) samples, respectively. Since its deployment on-board OPS-SAT in late 2020, FAPEC has allowed for downloading a large set of Earth Observation images. Recently, thanks to ESA Open Space Innovation Platform funds, these two algorithms from FAPEC are being improved to get better compression ratios and speeds, add video compression capabilities, and higher quality levels in case of lossy compression. A smart lossy approach is being developed for radio-frequency data, identifying the time segments with signal presence and quantizing noise-only samples to further reduce the size. In order to identify the really useful files to be downloaded from the satellite, on-board data analysis capabilities are being developed as well. In this work we present in-orbit results, recent developments and preliminary results obtained with the new algorithms on real data.

Los altos costes que implica la ejecución de cualquier ensayo real relacionado con la investigación en nanosatélites, así como la gran cantidad que recursos tanto humanos como temporales que estos requieren imposibilitan que cualquier institución educativa pueda ofrecer a su alumnado de forma generalizada la posibilidad de formarse en este ámbito. Este hecho ha generado una tendencia por parte de estas instituciones educativas superiores a sustituir el enfoque de enseñanza práctica por uno más orientado a al estudio teórico o la práctica a través de simulaciones computacionales. En este proyecto se lleva a cabo el desarrollo, diseño y fabricación a nivel mecánico y electrónico de un prototipo de pruebas enfocado al estudio tanto de los sistemas de control de actitud de un U1 CubeSat como de nuevas tipologías de placas fotovoltaicas basadas en patrones de Origami. En este prototipo se incluye tanto el diseño de un mecanismo de despliegue de dichas tipologías de placas fotovoltaicas desplegables como el desarrollo e implementación del dispositivo de control de actitud en el cual se incorpora dicho mecanismo. El desarrollo de este dispositivo también engloba una notable mejora en los subsistemas de medición, así como en el algoritmo de control de posición. El diseño tanto del bastidor del prototipo del U1 CubeSat como de los sistemas de control de actitud y el mecanismo de despliegue de placas fotovoltaicas es modular. Esto implica que cada uno de estos subsistemas puede funcionar de forma independiente al resto, lo que facilita en gran medida el estudio independiente de cada uno ellos y encaja a la perfección con la ideología de los CubeSats modulares, los cuales pueden variar sus funcionalidades dependiendo de los elementos añadidos. The high costs involved in carrying out any real test related to nano-satellite research, as well as the large amount of human and temporary resources that these requires, make it impossible for any educational institution to offer its students the possibility to be formed in this area. This fact has generated a tendency for these educational institutions to replace the practical teaching on this field by a more theoretical approach only practiced through computational simulations. However, this project carries out the development, design, and manufacture, at both mechanical and electronic level, of a test prototype focused on the study of the attitude control systems of a U1 CubeSat, as well as the new typologies of photovoltaic panels based on Origami patterns. This prototype includes both the design of an unfolding mechanism for these types of deployable photovoltaic panels, and the development and implementation of the attitude control device in which the mechanism is incorporated. Moreover, this project also covers notable improvements of both the measurement subsystems and the position control algorithm. The proposed design of the U1 CubeSat prototype frame, the attitude control systems and the photovoltaic panel deployment mechanism is modular. This implies that each of these subsystems can be operated independently from the rest, which greatly eases the study of each one of them and fits perfectly with the ideology of modular CubeSats, which can improve their functionalities depending on the added elements. Considering so, this prototype incorporates an attitude control device with a single reaction wheel and its corresponding MPU position sensor, as well as a mechanism for deploying photovoltaic panels based on Origami patterns. It should be noted that each of these systems includes its corresponding power supply, all controlled by an STM32 BluePill microcontroller and communicated through an HC-06 Bluetooth module.

With Differential GNSS (DGNSS), Single Differentiation (SD) of GNSS pseudorange mea- surements is computed with the aim of correcting harmful errors such as ionospheric and tropospheric delays. These errors can be mitigated to up to very few centimeters, which denotes a performance improvement with respect to the Standard Point Positioning (SPP) solution, widely used in GNSS receivers. However, with DGNSS it is necessary to have a very precise knowledge of the coordinates of a reference station in order to experience this performance improvement. We propose the Massive User-Centric Single Differentiation (MUCSD) algorithm, which is proven to have a comparable performance to DGNSS with- out the need of a reference station. Instead, N cooperative receivers which provide noisy observations of their position and clock bias are introduced in the model. The MUCSD algorithm is mathematically derived with an Iterative Weighted Least Squares (WLS) Estimator. The estimator lower bound is calculated with the Cramér-Rao Bound (CRB). Several scenarios are simulated to test the MUCSD algorithm with the MassiveCoop-Sim simulator. Results show that if the observations provided by the cooperative users have a noise of up to 10 meters, DGNSS performance can be obtained with N = 10. When observations are very noisy, the MUCSD performance still approaches DGNSS for high values of N.

This thesis presents a design of the system for the first stage of a mission in the NanoSat Lab, the 3Cat-8. There is an special focus on the control algorithm and the sizing of the actuators.

This work contains the analysis and improvements regarding attitude nanosatellite testing procedures. An utterly new system for measuring angular velocities has been designed from scratch in order to be applied to Cubesat testing campaigns. This system will help to track the rotations of the nanosatellite in the different tests. Knowing the angular velocity of the nanosatellite while performing the tests is so important. It allows to calibrate the gyroscopes as well as set a perfect and knows conditions to the satellite. Also, the measurements can be compared with the gyroscope angular velocityes obtained in order to recalibrate the system if necesary. Furthermore, a new design for Helmholtz coils software has been proposed using a user Interface in C++. This new software allows the user to initialize the coils with the desired magnetic fields required for testing. Two main operating ways has been considered: Static and Dynamic orbit magnetic field generation. Both systems can work altogether in order to check the attitude determination and control of the nanosatellite during testing campaigns. Nanosatellite needs to perform testing before its launch. Thus, the whole project avoids expensive risks which could doom the mission. The results obtained in this work show that the angular tracking works as desired for the testing purposes and the Helmholtz coils GUI simplifies a lot the testing process from the user point of view. Aquest treball conté l’anàlisi i les millores pel que fa als procediments de prova de nano satèl·lits d’actitud. Un sistema completament nou per mesurar velocitats angulars ha sigut dissenyat des de zero per aplicar-lo a les campanyes de proves de Cubesat. Aquest sis- tema ajudarà a seguir les rotacions del nano satel·lit en les diferents proves. Con `eixer la velocitat angular del nano satel·lit mentre es realitzen les proves és molt important, ja que permet calibrar els giroscopis així com establir unes condicions perfectes i conegudes al satèl·lit.

The objective of this project is the design of a Web App where the main characteristics of the orbiting Earth satellites can be intuitively, didactically and easily visualized. It has been sought to stablish a theoretic guide and brief explanations about how they operate, as well as a set of different maps where the basic information of the satellite can be available. The main source of information are the well-known Two-Lines-Elements (TLEs), a data format with a list of elements for a chosen object in a certain date, which, along with the propagator (Simplified General Perturbations, SGP4) provides every necessary data for the orbit characterization. The information of these TLEs is officially and publicly provided by Space-Track (project initially developed by the US Air Force) and the Celestrak Company (coworker of Space-Track). In addition, every component and library used in this project are for public use. Multiple functionalities were aimed to be integrated in the Web App: different views, information filtering, history, comparisons and calculations. But it is the 'families' section the one which has been developed extensively, since it can be the more attractive feature for the web users in the future. With this special feature, fields such as coverage, orbit description or the occupation of the space used are addressed. This project intends to clarify the outer space to the average user and bring the aerospace industry closer to those who have interest in the subject. That is why this web is listed as a disclosure project, given that, although it is a scientific project and deals with complex issues, it is created for all audiences and no deep prior knowledge is required to make use of it. For more sophisticated and complex studies, there are more appropriate tools than the project that is planned to be carried out. Incoming

Aquest treball ha rebut finançament del programa europeu DISCOVERER (Disruptive Technologies for Very Low Earth Orbit Platforms, EC-H2020-737183) This thesis studies the complementarity of VLEO satellite technologies with existing solutions in the telecommunications market, both in the space and terrestrial sectors. All the characteristics and particularities of VLEO orbits are defined and explained in detail, showing advantages and disadvantages compared to traditional higher orbits. Study of the deployment of the satellite constellation concept within the New Space framework. Next, the business opportunities that can be generated by the introduction of VLEO technologies in the telecommunications market are studied, analysing the possible reshaping of each vertical market and how can they be most benefited. Finally, a business opportunity is proposed and qualitatively analysed in detail using the Value Proposition Canvas methodology.

Modern satellites deployed in low Earth orbit (LEO) accommodate processing payloads that can be exploited for edge computing. Furthermore, by implementing inter-satellite links, the LEO satellites in a constellation can route the data end-to-end (E2E). These capabilities can be exploited to greatly improve the current store-and-forward approaches in Earth surveillance systems. However, they give rise to an NP-hard problem of joint communication and edge computing resource management (RM). In this paper, we propose an algorithm that allows the satellites to select between computing the tasks at the edge or at a cloud server and to allocate an adequate power for communication. The overall objective is to minimize the energy consumption at the satellites while fulfilling specific service E2E latency constraints for the computing tasks. Experimental results show that our algorithm achieves energy savings of up to 18% when compared to the selected benchmarks with either 1) fixed edge computing decisions or 2) maximum power allocation., Accepted in ICC Workshops 2022

During last years, space missions have evolved from monolithic spacecrafts architectures, to distributed ones, which are known as Distribute Satellite Systems (DSS). This spacecraft architecture has changed the space paradigm, as it has appeared the need of establishing communications between satellites to achieve the mission objectives. Despite this the need of simulating and emulating the communications between satellites, none of the available tools have complete inter-satellite communications capabilities. This final degree thesis presents contributions to the already existing simulator developed by NanoSat Lab. The contributions consist in the implementation of the Electric Power Supply (EPS) subsystem. Moreover, this thesis also contributes to the development of a Satellite Contact Emulator, developed by i2Cat, focusing on the development of the central PC that orchestrates the emulation. Recentment, les missions espacials han evolucionat d'una arquitectura basada en un sol satèl·lit, a una arquitectura distribuïda. Aquest tipus d'arquitectura és coneguda com a Distribute Satellite Systems" (DSS). L'aparició d'aquesta nova estructura ha provocat un canvi en el paradigma de l'espai, ja que ha sorgit la necessitat d'establir comunicació entre els satèl·lits per assolir els objectiu marcats de les missions. Tot i haver la necessitat d'emular i simular les comunicacions enter satèl·lits, cap de les eines actuals té suficients funcionalitats implementades per assolir aquesta emulació i simulació. Aquest treball de fi de grau presenta les contribucions fetes a un simulador ja existent, el qual ha estat desenvolupat pel NanoSat Lab de la UPC. La contribució feta consisteix en la implementació d'un subsistema que modeli una EPS. A més a més, aquest treball de fi de grau també contribueix en el desenvolupament d'un Satellite Contact Emulator, el qual ha estat desenvolupat per i2Cat. En aquesta contribució es farà menció especial en l'ordinador central que executa l'emulació. Recientemente, las misiones espaciales han evolucionado de una arquitectura basada en un solo satélite, a una arquitectura distribuida. Este tipo de arquitectura es conocida como Distribute Satellite Systems" (DSS). La aparición de esta nueva estructura ha provocado un cambio en el paradigma espacial, ya que ha surgido la necesidad de establecer comunicación entre los satélites para conseguir los objetivos de las misiones. Aunque exista la necesidad de emular y simular las comunicaciones entre satélites, ninguna de las actuales herramientas tiene las funcionalidades suficientes para conseguir dicha emulación y simulación. Este trabajo de fin de grado presenta las contribuciones hechas a un simulador ya existente, el cual ha sido desarrollado por el NanoSat Lab de la UPC. La contribución hecha consiste en la implementación de un subsistema que modela una EPS. Además, este trabajo de fin de grado también contribuye al desarrollo de un Satellite Contact Emulator, el cual ha sido desarrollado por i2Cat. Esta contribución pone un énfasis especial en el ordenador central que ejecuta la emulación.

Recently, there has been a paradigm shift in space missions. They no longer rely on a single satellite to achieve all the objectives of a mission. Responsibility is shared between devices that can communicate and share resources to achieve these objectives. This paradigm shift has increased the need to assess communication performance within FSS. Despite proposals for simulators and emulators to achieve this goal, none of them integrates the dynamics of satellites with their communications. This thesis presents two proposals and the implementation of one of them to extend the capabilities of the communication channel of the simulator developed by the NanoSat Lab of the UPC. Additionally, following the lines of the i2Cat Space Communications research group, a test bench is also presented to demonstrate the feasibility of a satellite contact emulator. As it will be demonstrated, developing such an emulator has not been possible. Finally, it is concluded that both parts of this thesis may converge. Thus, combining the possibilities offered by the current simulator with those available in the emulator under development. En el transcurso de los últimos años se ha observado un cambio en el paradigma en las misiones espaciales. Éstas ya no cuentan sólo con un único satélite que tenga que alcanzar todos los objetivos de una misión. Se reparte la responsabilidad entre diferentes dispositivos que son capaces de comunicarse y compartir recursos para alcanzar tales objetivos. De ese cambio de paradigma nace la necesidad de poder evaluar el comportamiento de las comunicaciones dentro de un FSS. A pesar de la existencia de simuladores y propuestas de emuladores para alcanzar tal objetivo, ninguno de ellos integra las dinámicas de los satélites con sus comunicaciones. En esta tesis, se presentan dos propuestas y la implementación de una de ellas para ampliar las capacidades del canal de comunicaciones del simulador desarrollado por NanoSat Lab de la UPC. Además, siguiendo las líneas del grupo de investigación de Comunicaciones Espaciales de i2Cat también se presenta un test-bed para demostrar la viabilidad de un emulador de contactos de satélites. Pues, como se va a demostrar, el desarrollador de uno como tal no ha sido posible. Por último, se concluirá que ambas partes de esta tesis puedan converger en algún momento combinando así las posibilidades que ofrece el actual simulador con las de un emulador que está en desarrollo. En el transcurs dels últims anys s’ha observat un canvi en el paradigma de les missions espacials. Aquestes ja no compten només d’un únic satèl·lit que hagi d’assolir tots els objectius d’una missió. Es reparteix la responsabilitat entre diferents dispositius els quals són capaços de comunicar-se i compartir recursos per tal d’assolir tals objectius. D’aquest canvi de paradigma neix la necessitat de poder avaluar el comportament de les comunicacions dins d’un FSS. Tot i l’existència de simuladors i propostes d’emuladors per assolir tal objectiu, cap d’ells integra les dinàmiques dels satèl·lits amb les seves comunicacions. En aquesta tesi, es presenten dues propostes i la implementació d’una d’elles per tal d’ampliar les capacitats del canal de comunicacions del simulador desenvolupat pel NanoSat Lab de la UPC. A més a més, seguint les línies del grup de recerca de Comunicacions Espacials d'i2Cat també es presenta un test-bed per tal de poder demostrar la viabilitat d’un emulador de contactes de satèl·lits. Doncs, com es demostrarà, el desenvolupant d’un com a tal no ha estat possible. Finalment, es conclourà que ambdues parts d'aquesta tesi puguin convergir en algun moment combinant així les possibilitat que ofereix l'actual simulador amb les d’un emulador que està en desenvolupament

La calidad del aire preocupa en muchas zonas urbanas y áreas industriales alrededor del mundo, y particularmente en la región europea, donde en 2019 casi 20 países superaron los valores de dióxido de nitrógeno NO2 límite impuestos por la Directiva de la Comisión Europea. Este estudio propone un análisis comparativo del impacto de los principales GEI entre 2019-2022. Los resultados destacarán sobre todo la dinámica de la contaminación por NO2 sobre la abrupta situación provocada por el brote de COVID-19, caracterizada por un disminución brusca de las intensidades del tráfico y las actividades industriales. Con ello surgen estas cuestiones: ¿Es la contaminación del aire exclusiva de zonas urbanas con grandes superficies industriales? ¿El confinamiento por COVID-19 ha propiciado cambios notables en las emisiones troposféricas? ¿Es el NO2 el gas más contribuyente al efecto invernadero? ¿Existe alguna relación entre las emisiones de NO2 y cambios en algún indicador de actividad económica? La qualitat de l'aire preocupa a moltes zones urbanes i àrees industrials al voltant del món, i en particular a la regió europea, on en 2019 casi 20 països superen els valors de diòxid de nitrógeno NO2 límits impostos per la Directiva de la Comissió Europea. Aquest estudi proposa un anàlisi comparatiu de l'impacte dels principals GEI entre 2019-2022. Els resultats destacaran sobre tota la dinámica de la contaminació per NO2 sobre la situació brusca provocada pel brot de COVID-19, caracteritzada per una disminució brusca de les intensitats del trànsit i les activitats industrials. Amb ell surgen aquestes preguntes: ¿És la contaminació de l'aire exclusiva de zones urbanes amb grans superfícies industrials? El confinament per COVID-19 ha propiciat canvis notables a les emissions troposfèriques? ¿És el NO2 el gas més contribuint a l'efecte hivernacle? ¿Existe alguna relació entre les emissions de NO2 i els canvis en algun indicador d'activitat econòmica? Air quality is a concern in many urban and industrial areas around the world, and particularly in the European region, where in 2019 almost 20 countries exceeded the NO2 nitrogen dioxide limit values imposed by the European Commission Directive. This study proposes a comparative analysis of the impact of the main GHGs between 2019-2022. The results will highlight in particular the dynamics of NO2 pollution on the abrupt situation caused by the COVID-19 outbreak, characterized by a sharp decrease in traffic intensities and industrial activities. This raises the following questions: Is air pollution exclusive to urban areas with large industrial areas? Has COVID-19 confinement led to significant changes in tropospheric emissions? Is NO2 the most greenhouse gas contributor? Is there a relationship between NO2 emissions and changes in any indicator of economic activity?

We have recently been able to witness how large companies have set themselves the goal of launching fleets of hundreds or even thousands of satellites to offer different services. This new generation of satellites is marking a clear trend to reduce their size and cost. However, this also leads to increasingly demanding challenges and constraints that require innovative solutions in the design of small-size, high-capacity communications systems. The present work offers the complete process from the design, to the implementation and test of a communications system for PocketQube picosatellites. The proposed solution benefits from LoRa technology, and includes both the hardware part of the communications subsystem and software for its configuration and operation according to the defined protocol. Finally, this project has been designed and integrated, and its compatibility and cooperation with the rest of the subsystems has been tested, for the PoCAT picosatellites developed at the UPC NanoSat Lab. Recientemente hemos podido presenciar como grandes compañías se han marcado el objetivo de lanzar flotas de cientos o incluso miles de satélites para ofrecer diferentes servicios. Esta nueva generación de satelites está marcando una clara tendencia a reducir el tamaño y coste de éstos. Sin embargo, esto también conlleva retos y restricciones cada vez más exigentes que necesitan soluciones inovadoras en el diseño de sistemas de comunicaciones de tamaño reducido y alta capacidad. El presente trabajo ofrece el proceso completo desde el diseño, pasando por la implemetación y test, de un sistema de comunicaciones para picosatelites PocketQube. La solución propuesta se beneficia de la tecnología LoRa, y comprende tanto la parte de hardware del subsistema de comunicaciones, como el software para su configuración y funcionamiento según el protocolo definido. Finalmente, este proyecto ha sido diseñado e integrado, y se ha probado su compatibilidad y cooperación con el resto de subsistemas, para los picosatellites PoCAT desarrollados por el UPC NanoSat Lab. Recentment, hem pogut presenciar com grans companyies s'han marcat l'objectiu de llançar flotes de centenars o fins i tot milers de satèl·lits per oferir diferents serveis. Aquesta nova generació de satèl·lits està marcant una clara tendència a reduir-ne la mida i el cost. No obstant, això també comporta reptes i restriccions cada vegada més exigents que necessiten solucions innovadores en el disseny de sistemes de comunicacions de mida reduïda i alta capacitat. Aquest treball ofereix el procés complet des del disseny, passant per la implementació i test, d'un sistema de comunicacions per a picosatèl·lits PocketQube. La solució proposada es beneficia de la tecnologia LoRa, i comprèn tant la part de hardware del subsistema de comunicacions, com el software per a la seva configuració i funcionament segons el protocol definit. Finalment, aquest projecte ha estat dissenyat i integrat, i s’ha provat la seva compatibilitat i cooperació amb la resta de subsistemes, pels picosatèl·lits PoCAT desenvolupats per l'UPC NanoSat Lab.

With the arrival of 5G networks, higher frequencies need to be used at the mmWave bands in order to find available and broad enough spectral bands. At these high frequencies, with very short wavelengths, any obstacle between the transmitter and the receiver will block the transmission. Furthermore, multipath transmission is not feasible since reflections produce a high reduction in the signal level. For this reason, free line-of-sight (LOS) is needed to achieve successful transmission. This study will provide a complete performance analysis at the network level considering multiple base stations, based on a statistical model of the positions of the base stations, of the blocking objects, and the shapes and sizes of these objects. The aim of this project is to develop a complete analysis of the effect of blocking elements such as buildings, which create no-line-of-vision (nLOS) regions and, therefore, lack of coverage. Con la llegada de las redes 5G, es necesario utilizar frecuencias más altas en las bandas de ondas milimétricas para encontrar bandas espectrales disponibles y lo suficientemente amplias. A estas altas frecuencias, con longitudes de onda muy cortas, cualquier obstáculo entre el transmisor y el receptor bloqueará la transmisión. Además, la transmisión multicamino no es factible, ya que las reflexiones provocan una gran reducción en el nivel de la señal. Por esta razón, se necesita una línea de visión directa (LOS) para lograr una transmisión exitosa. Este estudio proporcionará un análisis completo a nivel de red considerando múltiples estaciones base, basado en un modelo estadístico de la posición de cada una de ellas, de los objetos de bloqueo y las formas y tamaños de éstos. El objetivo de este proyecto es desarrollar un análisis completo del efecto de los elementos de bloqueo, como edificios, que crean regiones sin línea de visión (nLOS) y, consecuentemente, sin cobertura. Amb l'arribada de les xarxes 5G, s'han d'utilitzar freqüències més altes a les bandes d'ones mil·limètriques per trobar bandes espectrals prou amples i disponibles. A aquestes freqüències tan altes, amb longituds d'ona molt curtes, qualsevol obstacle entre lemissor i el receptor bloquejarà la transmissió. A més, la transmissió multicamí no és factible, ja que les reflexions produeixen una gran reducció del nivell del senyal. Per aquest motiu, es necessita una línia de visió directa (LOS) per aconseguir una transmissió exitosa. Aquest estudi proporcionarà una anàlisi completa a nivell de xarxa considerant múltiples estacions base, a partir d'un model estadístic de la posició de cadascuna, dels objectes de bloqueig i de les formes i dimensions d'aquests objectes. L'objectiu d'aquest projecte és desenvolupar una anàlisi completa de l'efecte dels elements de bloqueig com els edificis, que creen regions sense línia de visió (nLOS) i, conseqüentment, sense cobertura.

UPC NanoSat Lab is a laboratory located in the Universitat Politècnica de Catalunya, which is focused on the design and development of nano and picosatellite spacecrafts. This type of platforms have significant limitations in dimensions and structure. Nevertheless, due to its reduced cost, there is a high momentum as many companies and universities are investing their resources in innovative applications for Earth observation and communications. This thesis is part of a UPC NanoSat Lab project for the IEEE Geoscience and Remote Sensing Society called "Open PocketQube Kit". It aims at developing different educational PocketQubes, a type of picosatellite with a 5 cm cube size, which will be integrated in the 3Cat-8 mission. Precisely, this final degree thesis is focused on the design and implementation of the electrical power supply for these spacecrafts as well as a thermal analysis study for the whole of the structure. El UPC NanoSat Lab es un laboratorio de la Universidad Politécnica de Cataluña, que se centra en el diseño y desarrollo de nano y picosatélites. Este tipo de plataformes tienen limitaciones significativas en dimensiones y potencia. Sin embargo, debido a su coste reducido, existe un impulso creciente por parte de muchas empresas y universidades que estan invirtiendo sus recursos en aplicaciones innovadoras de observación terrestre y comunicaciones. Este trabajo de final de grado forma parte de un proyecto del UPC NanoSat Lab para la IEEE Geoscience and Remote Sensing Society titulado "Open PocketQube Kit" que tiene como objectivo desarrollar diferentes PocketQubes educativos, un tipo de picosatélites con forma de cubo de 5 cm de tamaño, los cuales irán integrados dentro de la misión del 3Cat-8. Precisamente, este trabajo de final de grado está centrado en el diseño e implementación del subsistema de alimentación eléctrica de estas plataformas así como un análisis térmico del conjunto de toda la misión. L'UPC NanoSat Lab és un laboratori de la Universitat Politècnica de Catalunya, focalitzat en el disseny i desenvolupament de nano i picosatèl·lits. Aquest tipus de plataformes tenen limitacions significatives en dimensions i potència. Tanmateix, degut al seu reduït cost, existeix un impuls creixent per part de moltes empreses i universitats que estan invertint els seus recursos en aplicacions innovadores d'observació terrestre i comunicacions. Aquesta treball de fi de grau forma part d'un projecte de l'UPC NanoSat Lab per l'IEEE Geoscience and Remote Sensing Society titulat "Open PocketQube Kit". Aquest projecte té com a objectiu desenvolupar diferents PocketQubes educatius, un tipus de picosatèl·lits, amb forma de cub de 5 cm de mida, que aniran integrats dins de la missió del 3Cat-8. Precisament, aquest treball de fi de grau està centrat en el disseny i implementació del subsistema d'al·limentació elèctrica d'aquestes plataformes així com un anàlisi tèrmic pel conjunt de tota la missió.

The project developed in this thesis consists of creating a PocketQube payload in charge of monitoring the 24 to 25 GHz band to enforce that the emissions of the 5G communications band are within limit. In this thesis, the design of the main RF circuit has been carried out. It has been divided in different sub-systems, for each of which, a PCB has been created to be able to test and characterize them. From those tests, information has been taken and was used to design the low frequency circuit, which includes the power supply and the inputs and outputs interface of the main RF circuit. El proyecto desarrollado en este trabajo de fin de grado consiste en la creación de una carga útil de un PocketQube destinada a monitorizar la banda de los 24 a los 25 GHz con tal de controlar que las emisiones de la banda de comunicaciones de 5G se encuentran dentro de los límites. En este trabajo de fin de grado, se ha realizado el diseño del circuito principal de RF. Éste ha sido dividido en diferentes sub-sistemas, para cada uno de los cuales, una PCB ha sido creada para testearlos y caracterizarlos. De estos tests, información ha sido extraída y usada para diseñar el circuito de baja frecuencia, el cual incluye la alimentación y la interfaz de entradas y salidas del circuito de RF principal. El projecte desenvolupat en aquesta treball de fi de grau consisteix en crear una càrrega útil per a un PocketQube encarregada de monitorar la banda dels 24 als 25 GHz per a controlar que les emissions de la banda de comunicació de 5G es troben dins dels límits. En aquest treball de fi de grau, s’ha portat a terme el disseny del circuit principal de RF. Aquest ha estat dividit en diferents sub-sistemes, per a cadascun d’aquests, s’ha creat una PCB per a poder testejar-los i caracteritzar-los. D’aquests tests, s’ha extret informació que s’ha utilitzat per dissenyar el circuit de baixa freqüència, que inclou l’alimentació i la interfície de les entrades i sortides del circuit principal.

La humedad del suelo es una variable muy importante en el sistema climático y en el medio ambiente, ya que es clave en el intercambio de agua y energia entre la superfície de la Tierra y la atmósfera. Actualmente, la misión Soil Moisture and Ocean Salinity (SMOS), la misión de la Agencia Espacial Europea (ESA), utiliza un radiómetro que trabaja en banda L para obtener mapas de la humedad del suelo en todo el mundo. Desde que el satélite está en òrbita, se ha intentado mejorar la resolución espacial de los mapes para obtener aplicaciones a nivel regional y local, como la detección de zonas inundables y el riesgo de incendio. Este proyecto consiste en el desarrollo de un algoritmo para mejorar la resolución espacial de los mapas de humedad del suelo hasta 20 metros utilizando cuatro variables: la humedad del suelo a 25 km (baja resolución), las temperaturas de brillo en las dos polarizaciones (horitzontal y vertical) a 25 km, la temperatura superficial terrestre (LST) y el índice de vegetación de diferencia normalizada (NDVI). Este último se ha obtenido de las medidas de Sentinel 2 a 20m de resolución espacial. Una vez obtenidos los mapas, se ha realizado un estudio de las medidas obtenidas y se han comparado con datos in-situ de una zona concreta de la Península Ibérica que incorpora sensores que miden la humedad del suelo diariamente, llamada zona REMEDHUS (Red de Estaciones de Medición de Humedad del Suelo de la Universidad de Salamanca), con el fin de analitzar la validez de los resultados. La humitat del sòl és una variable molt important tant en el sistema climàtic com en el medi ambient ja que és clau en l'intercanvi d'aigua i energia entre la superfície de la Terra i l'atmosfera. Actualment, la missió Soil Moisture and Ocean Salinity (SMOS), de l'Agència Espacial Europea (ESA), utilitza un radiòmetre que treballa en banda L per tal d'obtenir mapes de la humitat del sòl arreu del món. Des de que el satèl·lit està en òrbita, s'ha intentat millorar la resolució espacial dels mapes per tal d'obtenir aplicacions a escala regional i local, com la detecció de zones inundables i el risc d'incendi. Aquest projecte consisteix en el desenvolupament dun algoritme per tal de millorar la resolució dels mapes d'humitat del sòl fins a 20 metres tenint en compte quatre variables: la humitat del sòl a 25 km (baixa resolució), les temperatures de brillantor en les dues polaritzacions (horitzontal i vertical) a 25 km, la temperatura superficial terrestre (LST) i l'índex de vegetació de diferència normalitzada (NDVI). Aquest últim paràmetre s'ha obtingut de les mesures Sentinel 2 a 20 metres de resolució espacial. Un cop obtinguts els mapes, s'ha realitzat un estudi de les mesures obtingudes i s'han comparat amb dades in-situ d'una zona concreta de la Península Ibèrica que presenta sensors que mesuren la humitat del sòl de forma diària, anomenada zona REMEDHUS (Red de Estaciones de Medición de Humedad del Suelo de la Universidad de Salamanca), per tal d'analitzar la validesa dels resultats. Soil moisture is an important variable in both the climate system and the environment as it is based on the exchange of water and energy between the Earth's surface and the atmosphere. Currently, the European Space Agency (ESA)'s Soil Moisture and Ocean Salinity (SMOS) is a mission which uses a L-band radiometer to obtain soil moisture and ocean salinity globally and with a revisit time on the Equator of three days. Since the satellite is in orbit, many studies have been done to increase the spatial resolution of the soil moisture maps to obtain regional-scale applications, such as detection of flood zones and fire risk. This project consists on the development of an algorithm to increase the resolution of soil moisture maps up to 20 meters taking into account four variables: soil moisture at 25 km (low resolution), horizontal and vertical brightness temperatures at 25 km, land surface temperature (LST) and the normalized difference vegetation index (NDVI). This last parameter is obtained from the Sentinel 2 measurements at 20m of spatial resolution. Once the maps were obtained, a study of the measurements have been carried out and compared with in-situ data from a specific area of the Iberian Peninsula which has sensors that measure soil moisture daily, called REMEDHUS (Red de Estaciones de Medición de Humedad del Suelo de la Universidad de Salamanca), in order to analyse the validity of the results.

Traditional satellite communications missions are based on artificial satellites that can communicate with ground stations. This type of network provides wide-area coverage as well as resilient communications. Satellite systems are expected to be merged with the introduction of 5G/6G mobile systems to offer seamless connection and ubiquitous coverage for users worldwide. SDN/NFV are two of the most important enabling technologies for deploying new 5G/6G mobile network architectures, and they are widely used in telecommunications to deliver different services. Its method is based on network softwarization, which abstracts the physical infrastructure by separating the functionality of the hardware. Furthermore, using SDN, it is possible to reconfigure the network in flexible topologies that adapt to the performance necessary at any given time, thereby maximizing resources and lowering costs. SDN/NFV, on the other hand, relies on a strong and continuous network layer to construct a control plane and deploy VNF. However, establishing a stable link is difficult in constellations of several LEO/MEO satellites. TALENT is a software platform created with the purpose of supplying satellite and ground connection by coordinating satellite and terrestrial systems from a single location, developed under the SaTG5 project that defined the integration of satellite solutions for 5G. Regardless of these solutions, a robust testbed is required to help in the discovery of novel protocols for delivering and orchestrating network services over satellite networks that take dynamic network architecture on satellite constellations into account. This thesis addresses the lack of a testbed for deploying VNF via a satellite network, as well as the orchestration and deployment of VNF across various satellite constellations. Its main contribution is an update to TALENT to allow it to work with newer Open Source MANO versions, and a testbed for deploying a VNF across a simulated satellite network based on the OpenSand satellite simulation tool. Objectius de Desenvolupament Sostenible::9 - Indústria, Innovació i Infraestructura

In this report, we will explore the way to measure the angular position of a satellite, more precisely of a CubeSat, expressed with the Euler angles. We therefore consider all the rotations that are possible in a three-dimensional space. The measurements will be made via an image processing algorithm, using MatLab. The CubeSat is a relatively new technology, it is a small satellite, most of the time cubic and about 10 cm on each side. The CubeSats, as in our case, are used in the framework of educational projects, because of their convenient size. There are already internal devices that allow to know the attitude of the CubeSat. Thus, the final goal of these measurements is an external control, in order to verify the correct measurement of the CubeSat instruments. Dans ce rapport, nous allons explorer la manière de mesurer la position angulaire d’un satellite, plus précisément d’un CubeSat, exprimé avec les angles d’Euler. Nous considérons ainsi toutes les rotations réalisables dans un espace tridimensionnel. Les mesures seront réalisés via un algorithme de traitement d’images, sous MatLab. Les CubeSat sont une technologie récente, il s’agit d’un petit satellite, souvent de forme cubique, généralement de 10 cm de côté. Les CubeSat, comme dans notre cas, sont utilisés dans le cadre de projets pédagogiques, au vu de leur taille pratique. Il existe déjà des dispositifs internes qui permettent de connaître l’orientation d’un satellite. Ainsi, le but final de ces mesures est un contrôle externe, afin de vérifier la bonne mesure des instruments du CubeSat. Incoming

With the entry barrier for conventional small satellites continuously increasing for uni- versities and researches, this thesis means to promote a more accessible option in the form of a single unit picosatellite (1P). In this report, the design, implementation and testing procedures, alongside with the general mode of operation of these otherwise called PocketQubes will be presented. Three different configurations will be defined by means of three payloads: a VGA camera and two RFI Monitoring Receivers, at L-band and K-band. The avionics, constituting of an EPS, OBC, COMMS and an ADCS will remain mostly unchanged between the three variants. An IEEE GRSS initiative, the project has taken place, from designing to implementation and testing, within UPC?s NanoSat Lab, and is scheduled to be delivered in the shape of a kit, containing the Flight Models fully equipped with a set of manuals and tutorials for assembly, testing and operation, at the end of 2022. Additionally, a flight opportunity is envisioned for two of these PocketQubes aboard the NanoSat Lab?s future 3Cat-8 mission. Con la barrera de entrada de los pequeños satélites convencionales en continuo aumento para las universidades e investigadores, esta tesis pretende promover una opción más accesible en forma de un picosatélite de una sola unidad (1P). En este informe, el diseño, la implementación y los procedimientos de prueba, junto con el modo general de funcionamiento de estos, también llamados PocketQubes, serán presentados. Se definirán tres configuraciones diferentes mediante tres cargas útiles: una cámara VGA y dos receptores de monitorización RFI, uno en banda L y otro en banda K. La aviónica, constituida por los subsistemas EPS, OBC, COMMS y ADCS, permanecer a prácticamente sin cambios entre las tres variantes. El proyecto, una iniciativa del GRSS del IEEE, se ha llevado a cabo desde el diseño hasta la implementación y las pruebas en el NanoSat Lab de la UPC, y está previsto que se entregue en forma de kit, conformado por los modelos de vuelo Amb la barrera d’entrada als petits satèl·lits convencionals en augment continu per a les universitats i investigadors, aquesta tesi tracta de facilitar l’accés a una opció més assequible, en forma d’un picosatèl·lit d’1P. En aquest treball es presenten els procediments de disseny, implementació i proves realitzades, conjuntament amb els modes generals de funcionament d’aquests satèl·lits, anomenats PocketQubes. Es definiran tres configuracions diferents, segons la carrega útil a bord: una càmera VGA i dos sensors de RFI, un en banda L i l’altre en banda K. L’aviònica, constituïda per una EPS, una OBC, un sistema COMMS i el mòdul ADCS, romandrà pràcticament sense alteracions entre els tres models. Aquest projecte és una iniciativa del GRSS de l’IEE, i s’ha executat, des del disseny fins a la implementació i verificació, a les instal·lacions del NanoSat Lab de la UPC, i està pendent de ser entregat com a kit complet, incloent-hi els models de vol i el conjunt de manuals i tutorials de muntatge, proves i la operació, a finals de 2022. A més, es preveu una oportunitat de vol per a dos d’aquests PocketQubes a bord de la futura missió 3Cat-8 del NanoSat Lab.

This work presents an overview of the activity developed in the frame of a project funded by the European Space Agency (ESA). The research was focused on the study of the potential applications of GNSS Reflectometry (GNSS- R) over land, with an emphasis on soil moisture (SM) and biomass. A study about the sensitivity with respect to the freeze–thaw dynamics was considered as well. The work started with an analysis of the sensitivity of GNSS-R reflec- tivity collected by the TechDemoSat-1 (TDS-1) experimental satellite, although, to a limited extent, the Cyclone GNSS (CyGNSS) constellation was considered as well. The en - couraging sensitivity outcomes led to the development of retrieval algorithms: three different approaches for SM and one for biomass based on neural networks. A more theoretical investigation was carried out to better understand and predict the signal from a satellite platform which required the updating of two different models. To - pography effects and sensitivity to moisture and roughness of a rough soil were included as well as the effect of vegeta- tion cover. The project was carried out by a large team involving different research groups in Europe. It has led to main con- clusions and recommendations derived from a beneficial collaboration and fertilization of ideas. The primary ap - proaches and outcomes are summarized here, including comparisons to the recent literature. This study has been conducted in the framework of the ESA contract 4000120299/17/NL/AF/hh, “Potential of Spaceborne GNSS-R for Land Applications.” The TDS-1 data have been freely collected from the MERRBYS portal at merrbys.co.uk. The CyGNSS and SMAP data were downloaded from the NASA Earthdata portal at podaac.jpl.nasa.gov and nsidc.org/data/smap, respectively. The SMOS data are made available from the ESA through the smos-diss.eo.esa.int website. This work has also been partially supported by the project of the Ministerio de Ciencia, Innovación y Universidades and EU ERDF ref. RTI2018-099008-B-C21/AEI/10.13089/E01100011083, “Sensing with Pioneering Opportunistic Techniques,” and grant MDM-2016-0600 to the CommSensLab-UPC “María de Maeztu” Excellent Research Unit. We thank the ISMN for the availability of soil moisture data.

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes,creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. We address the evaluation of dynamic (estimation-based) user-decoding order in successive interference cancellation (SIC) in a proof-of-concept multiple access satellite setting in which many code-division multiple access users employ non-orthogonal spreading codes and the same encoder. We consider the practical setting where user symbol energies, unknown to the receiver, are estimated by preamble cross-correlations. Thereafter, SIC proceeds in non-increasing order of the former estimates. In contrast with small networks evaluated in the literature, we analyze the large-user regime and derive a simple system model to analyze the asymptotic network performance. Monte Carlo simulations validate our infinite-user analysis for hundreds of users and report the benefits of their application. Work supported in part by Agencia Estatal de Investigación (AEI, Spain) and by European Regional Development Fund (ERDF) through project WIN-TER (TEC2016-76409-C2-1-R) and project RODIN (PID2019-105717RB-C22), and in part by the Catalan administration (AGAUR) under Grant 2017SGR 578 and predoctoral Fellowship 2019FIB1 00085

Satellite simulators, such as STK, implement accurate models of the spacecrafts astrodynamics, which is crucial for some analyses. However, these simulators are insufficient simulating the networking aspects of satellites. For that reason the Distributed Satellite Systems (DSS) simulator has been implemented. The DSS is based on Network Simulator-3 (NS-3),and it is used to simulate communications of spacecrafts and constellations. The simulator allows to obtain metrics of contacts between the ground station and the satellite, and also of communications between satellites. I Distributed Satellite Systems (DSS), composed of multiple spacecraft units orbiting around the Earth, are becoming increasingly popular due to their ability to satisfy short revisit times and responsiveness. Furthermore, these DSS may be equipped with inter satellite communications and networking capabilities. Simulation techniques and computational support are required to develop and optimize such satellite structures. As a result, the major goal of the "DSS-Sim" (Distributed Satellite Systems Simulator), a project currently under development at the UPC NanoSat Lab, is to replicate all parts of this type of in-orbit architecture and analyse a variety of system-level properties. In this regard, this thesis describes the design and implementation in the DSS-Sim of two additional MAC protocols: an Aloha and a CSMA/CA MAC protocol. This thesis presents the design and implementation of the MAC protocols mentioned above, and a test section that describes the validation procedures for these protocols implemented on the DSS-Sim. Los Sistemas de Satélites Distribuidos (DSS), están compuestos por múltiples unidades de satélites que orbitan alrededor de la Tierra. Estos DSS se están volviendo cada vez más populares debido a su capacidad para satisfacer tiempos de revisita cortos y su capacidad de respuesta. Además, estos DSS pueden estar equipados con comunicaciones internas por satélite y disponer de sistemas con capacidades de red. Sin embargo, se requieren técnicas de simulación y soporte computacional para desarrollar y optimizar dichas estructuras de satélites. Por ello, el gran objetivo del "DSS-Sim" (del inglés ‘Distributed Satellite Systems Simulator’), proyecto actualmente en desarrollo en el NanoSat Lab de la UPC, es replicar todas las partes de este tipo de arquitectura en órbita y analizar una variedad de propiedades a nivel del sistema. En este sentido, esta tesis describe el diseño e implementación en el DSS-Sim de dos protocolos MAC adicionales: el Aloha y un protocolo MAC CSMA/CA. Esta tesis presenta el diseño e implementación de los protocolos MAC mencionados anteriormente, y una sección de pruebas que describe los procedimientos de validación para estos protocolos implementados en el DSS-Sim. Els Sistemes de Satèl·lits Distribuïts (DSS), estan formats per múltiples satèl·lits que orbiten al voltant de la Terra. Aquests DSS s’estan tornant cada cop més populars a causa de la seva capacitat per satisfer temps de revisita curts i la seva gran capacitat de resposta. A més, aquests DSS poden estar equipats amb comunicacions per satèl·lit internes i sistemes amb capacitats de xarxa. Tanmateix es requereixen tècniques de simulació i suport computacional per desenvolupar i optimitzar aquestes estructures de satèl·lits. Com a resultat, el principal objectiu del ‘DSS-Sim’ (de l’anglès ‘Distributed Satellite Systems Simulator’), un projecte que actualment està en desenvolupament al NanoSat Lab de la UPC, és replicar les parts d’aquest tipus d’arquitectura en òrbita i analitzar una varietat de propietats a nivell del sistema. En aquest sentit, aquesta tesi descriu el disseny i la implementació en el DSS-Sim de dos protocols MAC addicionals: l’Aloha i un protocol MAC CSMA/CA. Aquesta tesi presenta el disseny i implementació dels protocols MAC esmentats anteriorment, i una secció de proves que descriu els procediments de validació d’aquests protocols implementats al DSS-Sim.

Aquest ítem conté el treball original, defensat públicament, així com una versió millorada del mateix amb modificacions menors, autoritzada per l'escola The Earth observation industry has undergone a substantial transformation in the last decade. Until recently, Earth observation systems for the most critical commercial and institutional needs were mainly dedicated assets owned and operated by governments or big corporations, often at national level. Recent evolutions like the emergence of private investment and the development of appreciably cheaper instrumentation, systems and technologies in the field, such as the rise of CubeSats and SpaceX reusable launch rocket systems have disrupted the status quo into a new paradigm, labelled New Space. A possible further disruption into this new paradigm is the advent of High-Altitude Platform Systems (HAPS), also called Pseudo-Satellites. These systems feature unbeatable performance advantages in resolution and persistence at local observation against satellites. Nevertheless, no pseudo-satellite has yet been fully implemented, with a history of test failures and program funding terminations. This thesis explores the reasons for the technical lack of success of these initiatives (particularly an aeroelastic phenomenon called flutter) as well as reviews the necessary technologies needed for these systems to work, with a compilation of the past attempts through the scientific literature available. Finally, with a thorough examination of the economic and technological state of the art of the Earth observation industry and its applications, the study discusses the conditions under which the implementation of HAPS by an Earth observation company could be beneficial, making use of Alex Osterwalder's business model canvas methodology. Analysis demonstrates that HAPS companies could have the potential to disrupt the Earth observation industry through the implementation of videographic recording and real-time change monitoring, posing an attractive business case opportunity either for existing Earth observation companies or new entrants. So far, the constructors that have developed this technology the farthest are Thales Alenia Space with their aerostat system StratobusT'-1, as well as Airbus with their Zephyrnr UAV. Further research such a .. c.; financial budgeting and experimental results to prove client adoption should be carried out for companies interested in implementing these solutions.

Earth Observation (EO) is key for climate and environmental monitoring at global level, and in specific regions where the effects of global warming are more noticeable, such as in polar regions, where ice melt is also opening new commercial maritime routes. Soil moisture is also useful for agriculture and monitoring the advance of desertification, as well as biomass and carbon storage. Global Navigation Satellite System - Reflectometry (GNSS-R) and L-band microwave Radiometry are passive microwave remote sensing techniques that can be used to perform these types of measurements regardless of the illumination and cloud conditions, and -since they are passive- they are well suited for small satellites, where power availability is a limiting factor. GNSS-R was tested from space onboard the UK-DMC and the UK TechDemoSat-1, and several missions have been launched using GNSS-R as main instrument, as CyGNSS, BuFeng-1, or the FSSCAT [1] mission. These missions aim at providing soil moisture [2], ocean wind speed [3], and flooding mapping of the Earth. L-band microwave radiometry data has also been retrieved from space with SMOS and SMAP missions, obtaining sea ice thickness, soil moisture, and ocean salinity data [4]. The 3Cat-4 mission was selected by the ESA Academy "Fly your Satellite" program in 2017. It aims at combining both GNSS-R and L-band Microwave Radiometry at in a low-power and cost-effective 1-Unit (1U) satellite. Moreover, the 3Cat-4 can also detect Automatic Identification System (AIS) signals from vessels. The single payload is the Flexible Microwave Payload 1 (FMPL-1) [5] that performs the signal conditioning and signal processing for GNSS-R, L-Band microwave radiometry and AIS experiments. The spacecraft has three payload antennas: (1) a VHF monopole for AIS signals; (2) an uplooking antenna for the direct GPS signals; (3) a downlooking antenna that captures reflected GPS signals, and for the Microwave Radiometer. The downlooking antenna is a deployable helix antenna called the Nadir Antenna and Deployment Subsystem (NADS) which has a volume of less than 0,3U when stowed, achieving an axial length of more than 500 mm when deployed. As part of this mission, the design of the NADS antenna, its RF performance, as well as the environmental tests performed in terms of structural and thermal space conditions will be presented.

WUSAT-3 is a 3U CubeSat being designed to carry an experimental RF signal direction finding payload in Low Earth Orbit (LEO). Successful outcome of this experiment could lead to significant benefits for the field of wildlife monitoring from Space. Commercial adoption of this process would enable the development and use of much smaller, lighter RF tracking tags, which in turn would considerably increase the potential range of species that could be tracked by Satellites. The effect of the Covid-19 pandemic lockdowns has limited physical progress over the past 18 months, but the team continues to gain enormous experience and motivation from pursuing this exciting project with a very real-world mission. A recent return to near-normal working patterns has enabled the team to fully engage with the practicalities of progressing the previously produced WUSAT-3 Configuration Model, towards a testable Engineering Model. This paper outlines the development of both the initial chassis prototype (including mechanisms) and a subsystem FlatSat as a first stage towards building the complete Engineering Model. The chassis prototype was required to meet all the requirements of the FYS Design Specification [1], the NanoRacks CubeSat ICD [2], the CubeSat Design Specification [3] and those features identified by the outcomes of the WUSAT-3 Configuration Model. The FlatSat was required to include all subsystems capable of being constructed and tested without the availability of certain proprietary items that will be purchased later. The function and interface of these items, where it was necessary for the purpose of testing the assembled subsystem units that were available, was met by the design and inclusion of temporary substitute arrangements that provided similar performance. Systems Engineering methodologies were employed throughout as a means of ensuring that the design features of both chassis and FlatSat met all necessary requirements

Two universities joined forces to develop a shared ground segment (Ground Stations and Mission Operation Centers) for satellite signals reception, capable of working together autonomously in a network to receive telemetry data and decode information. The main objective of this cooperation and network is to, firstly, give both universities an infrastructure capable of receiving signals in VHF and UHF. Secondly, and most importantly, it aims to create an exchange of experiences between students from these universities while also contributing to the regional development of each country in nanosatellite data reception technology. The ground segment itself provides mutual data collection on a private server, using two ground stations located in different hemispheres to expand global coverage and minimize revisit time, which also contributes to supplying the nanosatellite telemetries database, which is being built in Portugal. The server architecture allows both universities to schedule future passes of their chosen satellites, recording them in a log file that can be used in future studies, enabling research groups to gain experience in signal processing analysis. The modular system is developed entirely using Commercial Of-The-Shelf (COTS) components and 3D printed parts, including Antennas, Amplifiers, Filters and also SDRs (Software Defined Radio), leaving the door open to new integrations that can expand frequency coverage, or system performance improvements. The design supports a wide variety of missions, operating on amateur radio frequency in VHF (2 m band of 144-146 MHz) and UHF (70 cm band of 430-440 MHz), enabling remote access and remote control of the antennas and their recorded data. All the ground segment architecture, hardware, and software, as well as its operational procedures, are discussed in this paper and can be found in detail on our public repository in GitLab. As of March 21st, it has completed several observations for verification. The results are being processed on a low-cost computer (Raspberry Pi4) connected to an SDR which in turn connects to the antennas. The assembly of this interface intends to give a friendly user experience and, if desirable, an easy expansion of this system. The project developed can be easily replicated in other locations around the world, mainly because of its low price and ease of use.

Cohesive Distributed Satellite Systems (CDSSs) is a key enabling technology for the future of remote sensing and communication missions. However, they have to meet strict synchronization requirements before their use is generalized. When clock or local oscillator signals are generated locally at each of the distributed nodes, achieving exact synchronization in absolute phase, frequency, and time is a complex problem. In addition, satellite systems have significant resource constraints, especially for small satellites, which are envisioned to be part of the future CDSSs. Thus, the development of precise, robust, and resource-efficient synchronization techniques is essential for the advancement of future CDSSs. In this context, this survey aims to summarize and categorize the most relevant results on synchronization techniques for Distributed Satellite Systems (DSSs). First, some important architecture and system concepts are defined. Then, the synchronization methods reported in the literature are reviewed and categorized. This article also provides an extensive list of applications and examples of synchronization techniques for DSSs in addition to the most significant advances in other operations closely related to synchronization, such as inter-satellite ranging and relative position. The survey also provides a discussion on emerging data-driven synchronization techniques based on Machine Learning (ML). Finally, a compilation of current research activities and potential research topics is proposed, identifying problems and open challenges that can be useful for researchers in the field.

The scientific mission objectives of the Stuttgart Operated University Research CubeSat for Evaluation and Education are meteor observation, measurement of the lower Earth's atmosphere during re-entry as well as technology demonstrations. The meteor observation is done by pointing a camera towards Earth and continuously taking images during Eclipse. Since it is not possible to downlink all images, an on-board detection algorithm is necessary and mission critical. Therefore, this algorithm needs to be tested thoroughly. Realistic test data showing meteors from orbit is needed to properly develop and test the algorithm. Existing videos, provided by the Planetary Exploration Research Center, captured from the ISS are used as a baseline but are not sufficient to test the algorithm. The videos do not have the diversity of meteors needed and the meteor properties are not settable which makes it difficult to test the detection algorithm in as many scenarios as possible. Therefore, an artificial meteor program was developed to simulate meteors with given properties as perceived from a meteor observation system in a low Earth orbit. Here, we present the details of the artificial meteor program, its working principle and how we tested an algorithm for meteor detection. The user can choose between different background videos, the existing ISS videos from PERC or the self-generated videos. Each different background is used to test a different aspect of the meteor detection algorithm. The ISS videos from PERC provide more diverse backgrounds than the self-generated videos with e.g., clouds and lightning. For these self-generated videos, a program is developed to take image sections of NASA’s Black Marble and putting them frame by frame together into a video. These videos are more suitable for simulating satellite rotation and camera properties. Independent of the background video, settable meteor properties contain important characteristics of a meteor like the light curve, brightness, speed, direction and shape. Additionally, the user can choose the meteor position in the video frame, in which frame it appears and which distance it covers. Furthermore, distortion settings can be applied which contain airplanes with adjustable parameters and scalable noise. Only a properly working meteor detection algorithm leads to a success of a mission critical part of the SOURCE CubeSat. Therefore, the development of this artificial meteor generation program is crucial. Furthermore, this technology demonstration of developing and especially testing a meteor detection algorithm will enable future space-based missions for meteor observations

The Educational Irish Research Satellite (EIRSAT-1) is a 2U CubeSat being designed, built and tested at University College Dublin. A FlatSat platform known as EIRFLAT-1 has been constructed to enable the testing and development of the CubeSat. EIRFLAT-1 facilitates the electrical connections between CubeSat components while leaving key interfaces accessible for test equipment and allowing for the hot swapping of components. Commercial Off The Shelf and in-house developed hardware has been tested using EIRFLAT-1 at component, subsystem and full system level. In addition, the FlatSat has been used for flight software development. This paper describes the design of EIRFLAT-1 including electrical and mechanical components and additional ground support equipment developed to assist in the testing and development activities. EIRFLAT-1 has proven to be an invaluable tool for testing and has led to the discovery of issues and unexpected behaviour with flight hardware which would have contributed to schedule delays if undiscovered until after the satellite was assembled. Moreover, EIRFLAT-1 facilitated early and incremental testing of both software and operations procedures. The schematics for the electrical design of EIRFLAT-1, which is compatible with all CubeSat Kit PC/104 components, has been made publicly available for use by other educational CubeSat teams

Student Satellite program at TalTech, Tallinn University of Technology, Tallinn, Estonia was initiated in 2014 with an aim to impart space technology knowledge to the Estonian students as well as assist towards development of new Space Technologies in Estonia. Two 1-Unit CubeSat named Koit and Hämarik that translates respectively as Dawn and Twilight in Estonian are part of the TalTech Satellite Program. The main scientific mission of the CubeSats was to demonstrate Earth observation and Optical Communication technology. Satellites had two types of cameras, an RGB Camera and an NIR Camera to carry out Earth Observation over Estonia. Testing High Speed Optical communication technology from LEO (Low Earth Orbit) was the second major scientific goal and for this purpose the CubeSats had LED (Light Emitting Diode). Koit CubeSat was successfully launched to space on-board Soyuz rocket on July 5, 2019 and Hämarik CubeSat was launched to Space on September 3, 2020 on-board Arianespace Vega Rocket. Koit CubeSat did not contact the Ground station for more than a year since its launch and it was assumed to be lost but on November 21, 2020 it made the first contact with the Ground Station. Hämarik CubeSat was first contacted on November 15, 2020. The team has been successful in updating software of Hämarik and further work is being done on the software with broader functions. Optical communication has not been tested yet because ground station for optical communication has not been developed yet but a good achievement in the path to optical communication was to see the satellites with small hobby telescope and one of the satellite team member was successful to detect the Hämarik CubeSat on 17 August 2021 which was at a distance of about 792 Kilometres. Satellite team is in contact with the Hämarik and has been successful to download a few thumbnails and is working to establish a quick data connection with it and determine its exact position so that the cameras can be focused towards the Earth in order to get the whole images captured by the CubeSat.

Faculty members, undergraduate and graduate students of the School of Communication and Aerospace Engineering (Polytechnical University of Catalonia) are participating in a series of studies to determine the thermospheric density. These studies involve planning a space mission, designing and constructing small satellites, and performing related data analysis. This article presents a method for determining the thermospheric density and summarises the academic context in which we develop our work. Several studies have reported the existence of a downtrend in thermospheric density, with relative values ranging from –2% to –7% per decade. Although it is well known that solar and geomagnetic activity are the main drivers of the variations of the thermospheric density, this downtrend was reported to be caused by the rise of greenhouse gases. We present an update of this progression, considering the last solar cycle (2009-2021) and using Two-Line Elements sets (TLE) of 1U CubeSats and the spherical satellites ANDE-2. TLEs were used to propagate the orbits numerically using SGP4 (Simplified General Perturbations), and then compute the average density between two consecutive TLEs by integrating the appropriate differential equation. Then, using the NRLMSISE-00 (Picone 2002) and JB2008 (Bowman 2008) atmospheric models, we calculated an average density deviation per year. We built a comprehensive time series of the thermospheric density values, ranging from 1967 to the present. We merged Emmert (2015) thermospheric density data and our results computed both with NRLMSISE-00 and with JB2008. A linear regression on the combined dataset yields a decreasing trend of –5.1% per decade. We also studied the geomagnetic and solar activity to isolate the possible greenhouse gasses effect during the considered period. Our results show a strong correlation between geomagnetic activity and density deviation near the solar minima, and we propose that the cause of the previously reported long-term density deviation could be a poor adjustment of the effects of geomagnetic activity. Finally, we proved that orbital information from small satellites could be efficiently used to assess the evolution of thermospheric density variations. Additional data obtained from future missions (as the one proposed by our group) will eventually allow a better characterisation of the atmospheric density and help disentangle the possible greenhouse gasses effects on its variations

The Earth Observation Satellite System Design training course was first offered in 2018 at ESA Academy’s Training and Learning Facility at ESA’s ESEC Galaxia site in Belgium, and again in 2021 in an online format under the Covid-19 pandemic situation. The course covers the end-to-end design and development process of satellite Earth observation systems. Two major challenges were faced by the teaching experts, consisting of the active and retired ESA staff, as well as ESA Academy’s instructional designers for its development: (1) Condensing such a vast subject domain, associated with a complex, multi-disciplinary engineering undertaking, into a compact format (e.g. 4.5 days in 2018) without sacrificing the quality of the essential technical knowledge, engineering practices and logic as taught; (2) Presenting the course materials in a comprehensive form to a group of 30 M.S. and Ph.D. students with their backgrounds generally not covering all of the technical disciplines associated with the course subject domain. The 2021 online edition of the training course, which drew on lessons learnt from 2018, consisted of 18 lectures, plus 5 group project sessions where the students put their acquired knowledge into practice and learned to work in a project team environment. This paper concentrates on the approach and logic adopted by the instructional team to address the above 2 challenges. Difficulties encountered in some of the areas, e.g. remote sensing instrumentation designs, are discussed