Mission Design for the CubeSat OUFTI-1

CHAPTER 1010.1 Communication hardwareThe hardware for satellite D-STAR communication has never been built untilnow: it’s the main grey area of the project. In fact, a traditional D-STARground repeater is composed by a series of boxes with dimension and massdefinitely incompatible with a CubeSat: everything has to be reduced at mostand some functionalities will be cut out.We are not going to give detailed information on the subject as it’s part of another thesis on OUFTI-1 [RD5]. Anyway a brief introduction of the hardwareis almost compulsory.The system is shown in block diagram in figure 10.1Figure 10.1: Communication system block diagramThe signal at 145 MHz frequency is received, amplified and demodulated.Voice and data stream are then separated. The low rate stream is then searchedfor command packages and, if any, they are analyzed, verified as originating fromthe Reference Control Station and then processed if suitable. In this case, downlinkdata are fitted with requested telemetry information. Otherwise, receivedlow rate user’s data are recombined without additional delay with the receivedvoice stream, modulated, amplified and sent back immediately via the downlinkpath at 435 MHz frequency.The mode of operation is a voice based system called DV mode: it runs at4800 bds, 0.5 GMSK modulated. It is made by 3600 bds AMBE encoded voicestream (2400 bds voice + 1200 bds FEC) and a low speed uncorrected dataGalli Stefania 98 University of Liège