Telecommunication Subsystem Design for Small Satellites

Satellite design has always been considered as an extremely expensive and high risk business which not only requires vast knowledge and expertise but also extensive budget. Primarily, this concept was based on initial development and launching cost. Secondly, it was impossible to repair and substitute parts in space (this was true up to 1993: the first Hubble Space Telescope servicing mission), which made the design more tough because it required advanced fault tolerance solutions and extreme reliability. With the passage of time academic entities and small companies have also entered this market. Low cost design techniques have played an important role in the aerospace market growth over the recent years, but they can still play an important role in future developments. At present, several private companies are also providing an affordable launch services which lowers the accumulative cost. Many universities and Small and Medium Enterprises (SMEs) worldwide are trying to further reduce the satellite costs. One recent example of these efforts is the CubeSat concept: a really small satellite, built using commercial components. This thesis work also proceeds in the same direction: the novel AraMiS (Italian acronym for Modular Architecture for Satellites) architecture and its different tiles (main subsystem) will be described. The goal of AraMiS is to progress beyond the concept of CubeSats and create a true modular architecture. The main idea of the AraMiS is modularity at mechanical, electronic and testing levels. These modules can then be assembled together to get desired requirements for the targeted mission, which allows for an effective cost sharing between multiple missions. This thesis deals with the design and development of telecommunication subsystems for AraMiS Project and in particular for AraMiS-C1 satellite on a single CubeSat standard module called tile. The implementation of S-band transceiver over the half of telecommunication tile is not a trivial task. Several techniques were employed to make possible such a reduction interms of size, weight and power consumption while still achieving desirable performance for communication link. COTS components have been used for 1B9_CubeTCT sub modules implementation. COTS particularly for RF Front End design were selected on the basis of performance in harsh LEO environment, power losses, dimension and space occupied onboard 1B9_CubeTCT. In order to cope with such anomalies on the 1B9_CubeTCT Subsystem; different housekeeping sensors have been employed at various point of the tile. This thesis work also elaborates on the S-band antennas design for both versions of AraMiS satellites with uses innovative technique to enhance performance while keep the size, weight and cost within acceptable margins. The first couple of chapter presents an introduction to AraMiS project and AraMiS-C1 satellite. In chapter 3 there is a discussion of different satellite design flow configurations. The chapter 4 comprehensively discusses the 1B9_CubeTCT, which is the CubeSat standard telecommunication tile developed for AraMiS-C1 and other CubeSat standard nano-satellites. It consists of S-band and UHF OBRF modules which provide radio communication link between satellite and the earth. It also gives an indepth explanation on the design and development of each sub-module onboard 1B9_CubeTCT that includes CubeTCT S-band transceiver, RF front end, Housekeeping Sensors, Tile Regulators, anti-latchup protection circuit and RF matching network. Chapter 5 deals with the S-band antenna design, fabrication and testing for conventional AraMiS architecture and AraMiS C-1 satellite. It explains in detail, the design, implementation and testing of single patch antenna and AraMiS patch array that are used for AraMiS C-1 and Conventional AraMiS satellites respectively. The chapter 6 provides link budget estimation for different scenarios, ranging for worst to the best possible case. A brief description on the Polito ground station and its key attributes is also provided. The Link budget estimates for other ground stations (GENSO members) are also performed and feasibility of developed 1B9CubeTCT hardware is verified. Chapter 7 introduces the AraMiS protocol, developed in compliance with GENSO project which aims for providing an extended communication link for a satellite (remotely via internet), by using a GENSO member ground station around the World. A new frame format is defined which makes AraMiS satellite compatible with GENSO. Later in the chapter are presented different possible scenarios of AraMiS Protocol mechanism during normal operation case and also in case of packet loss (in both uplink and downlink communication.)