SDR board design with high-speed IQ modulator and data interface

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Jánosi Gergely Péter
Department of Networked Systems and Services

My task for this thesis was to design an SDR-based, space compatible PCB (Printed Circuit Board) and circuit diagram. The system should be capable of receiving high-speed data and transmitting this data to earth. For the receiver I used a Wizardlink interface.

Signal processing systems are essential for SDRs. I implemented this with a Virtex-5QV FPGA (produced by Xilinx). Other important parts of the system are the DAC5670-SP DA converter and the ADL5386 IQ modulator. The DA converter converts the digital data arriving from the FPGA to an analog signals, and then the IQ modulator modulates these analog data.

Part of my task was to keep in mind that the finished product must be able to operate in space. I present the hardships of space operation that space-engineers have to face, highlighting challenges and harsh environmental conditions outside the Earth's atmosphere in Chapter 1. Then, I present the difficulties of launching space devices mentioning the Van Allen belt and power management issues.

In Chapter 2 I present the definition of software-defined radio (SDR) and then I explain the features and general architecture of it. Next I present the theoretical background of the two most important elements of SDR: the DA converter and the IQ modulator.

In Chapter 3 I present the finished system and hardware design. After that I go through the building blocks of the system explaining each part's inner architecture and how they fit into the whole system. Then I give an estimate of the current drain and power consumption of the finished product. Finally I describe the hardware designing software (Altium Designer) and I give advice of part placement on the PCB.


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