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Inertial measurement units (IMUs) are key components of various applications including navigation, robotics, aerospace, and automotive systems. IMU sensor characteristics have a significant impact on the accuracy and reliability of these applications. In particular, noise characteristics and bias stability are critical for proper filter settings to perform a combined GNSS/IMU solution. This paper presents an analysis based on the Allan deviation of different IMU sensors that correspond to different grades of micro-electromechanical systems (MEMS)-type IMUs in order to evaluate their accuracy and stability over time. The study covers three IMU sensors of different grades (ascending order): Rokubun Argonaut navigator sensor (InvenSense TDK MPU9250), Samsung Galaxy Note10 phone sensor (STMicroelectronics LSM6DSR), and NovAtel PwrPak7 sensor (Epson EG320N). The noise components of the sensors are computed using overlapped Allan deviation analysis on data collected over the course of a week in a static position. The focus of the analysis is to characterize the random walk noise and bias stability, which are the most critical for combined GNSS/IMU navigation and may differ or may not be listed in manufacturers’ specifications. Noise characteristics are calculated for the studied sensors and examples of their use in loosely coupled GNSS/IMU processing are assessed. This work proposes a structured and reproducible approach for working with sensors for their use in navigation tasks in combination with GNSS, and can be used for sensors of different levels to supplement missing or incorrect sensor manufacturers’ data., This research was funded by Rokubun S.L. and Universitat Politècnica de Catalunya with industrial PhD grant number 2020 DI 108 from the Generalitat de Catalunya; This research was partially funded by the Spanish Ministry of Science and Innovation and European Union FEDER through projects CNS2022-135383 and PID2022-138485OB-I00., Peer Reviewed, Postprint (published version)

This final degree project focuses on the development of a GNSS (Global Navigation Satellite System) receiver block, based on a radiofrequency switching matrix. The main objective is to take the first step towards the operability of the satellite navigation system and the receiver for reflectometry and radio occultation experiments. This project is carried out in collaboration with UPC NanoSat Lab, a department of the Universitat Politècnica de Catalunya specialized in launching nanosatellites for earth observation. Specifically, within the framework of the 3CAT-8 mission, the phenomenon of ionospheric scintillation is being investigated, that is, how radiofrequency waves are affected when crossing the ionosphere. Additionally, it aims to monitor radio frequency interference (RFI) in the L and K frequency bands as a secondary objective. This project involves a deep theoretical study on GNSS concepts and their implications in reflectometry and radio occultation fields. Next, the different subsystems of the satellite are thoroughly explored for the generation of a comprehensive design that will integrate existing antennas with receivers, considering the scientific requirements of the mission and selecting components according to space standards. Furthermore, the necessary printed circuit boards are developed for efficient integration of the switching matrix with the rest of the satellite subsystems, always respecting the basic characteristics of GNSS signals and their fundamental properties. This project represents the first step towards the culmination of the satellite system responsible for conducting the scientific tests of the 3CAT-8 mission.

El present treball de fi de grau avalua els diferents tipus sistemes GNSS, determinant els components essencials que han d'adquirir-se per a aconseguir un sistema funcional. S'analitzaran les diferents constel·lacions determinant si és millor utilitzar un únic sistema com podria ser el GPS o el Galileu o si seria més eficient utilitzar la combinació de diferents constel·lacions de satèl·lits. El projecte es realitza sota la supervisió i suport dels membres del CDEI-UPC amb els quals es treballarà conjuntament per a definir i aconseguir els reptes proposats. Una vegada determinat quals són els components necessaris, es formalitzaran reunions amb diferents proveïdors de sistemes GNSS per a triar el sistema que compleixi amb el major nombre d'especificacions i objectius que es proposen durant el treball i es testessin els sistemes triats per a així prendre decisions basats en les dades reals comprades amb teòrics proporcionats pels fabricants. Per últim, s'analitzarà la viabilitat de la integració del sistema triat en el robot mitjançant l'ús del llenguatge ROS per a així en les següents fases del projecte dur a terme la integració física del sistema, El presente trabajo de fin de grado evalúa los diferentes tipos sistemas GNSS determinando los componentes esenciales que deben adquirirse para conseguir un sistema funcional. Se analizarán las diferentes constelaciones determinando si es mejor utilizar un único sistema como podría ser el GPS o el Galileo o si sería más eficiente utilizar la combinación de diferentes constelaciones de satélites. El proyecto se realiza bajo la supervisión y soporte de los miembros del CDEI-UPC con los cuales se trabajará conjuntamente para definir y conseguir los retos propuestos. Una vez determinado cuales son los componentes necesarios, se formalizarán reuniones con diferentes proveedores de sistemas GNSS para escoger el sistema que cumpla con el mayor número de especificaciones y objetivos que se proponen durante el trabajo y se testearan los sistemas escogidos para así tomar decisiones basados en los datos reales comprados con los teóricos proporcionados por los fabricantes. Por último, se analizará la viabilidad de la integración del sistema escogido en el robot mediante el uso del sistema operativo ROS para así en las siguientes fases del proyecto llevar a cabo la integración física del sistema, This thesis evaluates the different types of GNSS systems by determining the essential components that must be acquired to achieve a functional system. The different constellations will be analysed to determine if it is better to use a single system such as GPS or Galileo or if it would be more efficient to use a combination of different satellite constellations. The project is carried out under the supervision and support of the members of the CDEI- UPC with whom I will work together to define and achieve the proposed challenges. Once the necessary components are determined, meetings will be formalized with different GNSS system providers to choose the system that meets the highest number of specifications and objectives proposed during the work, the chosen systems will be tested in order to make decisions based on the real data purchased with the theoretical data provided by the manufacturers. Finally, the feasibility of the integration of the chosen system in the robot will be analysed through the use of the ROS language to carry out the physical integration of the system in the following phases of the project.

This project combines GNSS-R technology and UAVs in the context of the aerial remote sensing field, from the design of the assembly of the UAVs and GNSS-R to the execution of the different tests, as well as the data collection and analysis. As it will be seen in the document, this analysis has allowed to improve the original design of the system. The remote sensing technology based on GNSS reflected signals is simply called GNSS-R, and the greatest advantage of UAV as a mounting platform is the low cost, high system availability, and fast installation. Thus the main task of this project is to experimentally verify the possibility of CTTC's own developed GNSS-R working with UAVs. In this report, first I explain some basic principles of GNSS and GNSS-R, as they are important technical backgrounds for the whole project. Secondly, I describe the application of the RTKPOST software, which is an important processing and analyzing tool in the entire project, mainly describing the positioning methods used in the different processing modes in RTKPOST, also the parameter needed for analysis. Then, the design of the UAV-GNSS-R assembly is discussed, with different options based on the characteristics of the UAV, such as weight, payload space, and so on. The whole experimental process is also explained, and all the test data are analyzed and processed by using the Static mode or Kinematic mode in RTKPOST, and the data results are analyzed and compared in terms of satellite visibility, signal-to-noise ratio, elevation angle, Standard Deviation and Root Mean Square. The experimental process is roughly divided into three parts. The initial verification test is used to collect signal data as a basis, through which it is found that drone interferes with GNSS-R to a greater extent, and that the reflector antenna cannot receive the signal if the drone is placed too close to the ground. The second part of the experiment is a stationary test, where the UAV is placed on a tripod, and it', Objectius de Desenvolupament Sostenible::11 - Ciutats i Comunitats Sostenibles

This paper proposes a proper compass adjustment method using only a GPS (or any other GNSS receiver) and a single visual reference to enhance the efficiency of compass adjustment. During compass adjustment, the ship proceeds on magnetic courses using a gyroscopic or satellite compass and considering magnetic declination. However, non-magnetic compasses are only compulsory for ships of 500 gross tonnage or upwards (SOLAS V/19.2.5.1). Many ships of less than 500 gross tonnage have only a magnetic compass to indicate heading. In these cases, a minimum of five leading lines or a minimum of five bearings of conspicuous and distant points or sun azimuths are necessary to adjust the compass. This makes compass adjustment more laborious and time consuming. To expedite this process, a reliable and practical method was developed to use the courses over ground given by a GNSS receiver and a single visual reference instead of the headings provided by a gyroscopic or satellite compass. The method is valid for all ships, but is primarily intended for those equipped with only a magnetic compass to indicate heading., Postprint (author's final draft)