During the work on my thesis I participated in the European Space Agency’s (ESA) ESEO (European Student Earth Orbiter) project, the goal of which is to develop and launch an entire sattelite to Low Earth Orbit. The Space Research Group at BUTE takes part in this project, developing one of the experiments onboard and the sattelite’s Power Distribution Unit (PDU).
I got acquainted with the structure of the satellite, the functional subsystems and the payload. I got acquainted with the structure and operation of satellite’s power distribution unit and the communications protocol between the onboard data handling system and the PDU. During my work I participated in the testing of the communication lines.
Due to the physical conditions in space and the satellite’s different subsystems the communication lines are exposed to a large amount of interference. My task was to learn of the different methods used to prevent and detect errors caused by these.
I got acquainted with the highly effective error preventing low voltage differential signalling (LVDS) method. I got acquainted with different error detecting methods used in satellite applications, particularly with Cyclic Redundacy Check (CRC), it’s mathematical base, hardware and software implementations and the selection of generator polynomials, which is the most determinate factor of the efficiency of CRC based error detection. I got acquainted with the structure of the linear feedback shift regiszter (LFSR) and it’s application in CRC generating and verifying.
I got acquainted with the test setup created to test the PDU and with the PC software created to send and receive messages. Due to the change in the lauch date of the satellite the modification of the software to be able to use CRC error detecion was not done solely by me. After the completion of the software I took part in the testing of the PDU’s communication.