S-Band communications design and implementation for 3Cat-6

The Nanosatellite and Payload Laboratory (UPC NanoSat Lab) is a cross-departmental initiative belonging to the Barcelona School of Telecommunications Engineering. Its main activity is the development and design of nano-satellite missions, with its focus on the exploration of innovative small spacecraft system concepts and developing and integrating subsystems and payloads for Earth Observation. The laboratory is currently developing the 'Remote Sensing and Interference Detector with Radiometry and Vegetation Analysis', also known as RITA Payload, which is one of the Remote Sensing payloads that was selected by the second GRSS Student Grand Challenge in 2019 to fly on board of the AlainSat-1. This Payload is being developed under the supervision of the IEEE GRSS. This thesis aims to contribute to the development of the RITA mission with the design and implementation of the payload's S-Band communications. It begins with a study of satellite communications and particularly S-Band, focusing on its usefulness in the downlink of scientific results. Moreover, it presents a study of the communications scenario containing orbital simulations as well as a link budget, providing crucial information for the system's design and decisive in establishing the necessary requirements. The standards used by the European Space Agency for its missions are evaluated for their viability in this mission, with the boundary conditions that apply to them. Thus, a variation of traditional communication schemes is developed for the RITA mission, and the design process is explained in detail. The main core of the thesis consists of the implementation and design of the system. This is been split into three main sections, the application layer, the channel coding and the physical layer. On the one hand, the application layer includes the necessary protocols, frame design and systems to transform files into packets to be sent, and on the other way around, to recover files from a number of packets. On the other hand, channel coding includes all the coding and decoding systems to ensure that the system is able to recover the initial data if errors occur in the physical channel of the transmission and reception. Finally, the physical layer includes the transmission of symbols and the reception of signals, together with the necessary signal processing techniques to ensure the initially transmitted frames can be recovered correctly even if deep fading¿s or Doppler shifts have affected the received system. The thesis also presents several tests that verify the correct functioning of the system using two ADALM-PLUTO SDR devices, representative of the hardware that will be used in the satellite, to work as transmitter and receiver. The thesis concludes with a verification of the system, commenting on the difficulties and problems that have arisen during its development, and the work that should be carried out before the launch

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

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