UHF Radio Frequency Modules for Satellite-Ground Communication

This thesis is devoted to the development of a bidirectional telecommunication system for
space applications. The module is going to be integrated in the AraMiS architecture, that is
an innovative philosophy of small satellites based on tile-modularity and the use of low-cost
commercial components.
The objective is to design the electronic board, the antenna apparatus and the control
software to handle both the communication protocol and the housekeeping functions. According
to the AraMiS specications, the main constraints are collected in Table I.
TABLE I: ARAMIS SPECIFICATIONS FOR THE UHF TELECOMMUNICATION SYSTEM
Frequency Rate PTXsatellite PTXground Interface On board supply Size
437 MHz 9:6 Kbps 33 dBm 47 dBm SPI [12 􀀀 18] V; 15 W 165×165 mm2
After an introduction referring to space-environment related issues and the state of the
art in university satellites, the hardware design is carried out. Technical choices related to
frequency selection, modulation and suitable equipment are taken and justied according to the
power budget, project constraints and the availability of specic products on market. A set
of devices is analyzed in terms of key-parameters in order to lter the most appropriate ones
for each goal, then main block-schematics are provided. By means of specic CAD tools, both
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SUMMARY (continued)
schematics and PCB implementation are performed and depicted in the following chapters, then
the C++ control software is designed to drive the communication system, the processing unit
and all the housekeeping sensors. Since only COTS components are going to be used due to
the low-cost goal and those are neither space dedicated nor radiation robust, both protection
circuits and specic software routines must be implemented in order to keep electronic boards
in safe operating region. Such a precaution is fundamental to prevent the mission failure in
case of SEUs. After that, the propagation environment is studied and the most common UHF
radiating systems for satellite-ground communications are described. Finally, a suitable AraMiS
antenna and specic microwave circuits are designed to ensure both impedance matching and
high radiation eciency in the band of interest.
In order to assure the system compatibility within the AraMiS framework and full technical
integration with the other subsystems, a UML description for the entire project documentation
is developed and steadily updated in the project library.