This paper is about designing and realizing a radio transmitter and receiver module, which can be used to transmit the data from a high definition camera (or possibly other signal source eg. thermocamera) on board of an unmanned aerial vehicle to the ground control station. The whole task is highly complex: receiving the data from the source, processing, channel coding, and finally modulation and transmission, at the ground control station the aforementioned tasks in reverse order, amended by antenna positioning, switching operations. From all these tasks I chose to design the air station and ground station RF stages, the analog-digital and digital analog interfaces.
In the first part I discuss the principles of the direct conversion radio, operation modes, advantages and disadvantages, the practical difficoulties that are faced, and the usually applied modulation methods. I compare to the superheterodyne radio, I also pan about why it is advantageous in such an UAV to use this method.
The second part is about the constuction of the radio modules, I describe the demanded physical and electrical properties, I outline the system to be designed. Then I describe the specific hardware elements to be used, and the design flow itself.
Finally, I outline the structure of the hardware to be implemented in the FPGA, panning about the role and theory of operation of each subpart.