Software Defined Radio

The below abstract is excerpted from the first chapter of Brandon Burgett's thesis. The thesis has not been published yet. For more information regarding the project, contact SSEP.

Proposed Project Description

The project proposed will be the beginning of a full CubeSat communication system. It will consist of a microcontroller to control the different modulation schemes and data rates, a FPGA to implement the different schemes and a stand in high frequency exciter that can be different frequencies if they are desired. The reason for making the system use these three different sections is to allow for maximum modularity and flexibility in the future for adding different features. This will ultimately be the starting point for software defined radio communications for the UAF Space Grant program. Figure 1 shows the basic structure for the proposed communications system and consists of a microcontroller, an FPGA and RF front end.

Reworking the architecture of the communication systems at UAF will serve multiple purposes. First off it will allow for higher data rate and longer range missions without compromising the link quality. Using the different modulation protocols enables the adjustment based on channel capacity and if set up correctly will allow close to the maximum data throughput. Second, a new design is desired to allow for the easy expansion into new modulation protocols and frequency bands as missions require. With a system that is flexible and powerful, the starting design for the new software defined communication board will enable a new era of space exploration at UAF.

The rest of this thesis will be devoted to describing each of the components of the systems that are designed. Chapter 2 will detail the LabView portion of the design and how to use and make changes to it in the future. The LabView code will reflect and be compatible with the system that is designed for insertion into the CubeSat. Chapter 3 will detail the design elements of the FPGA portion of the communications systems and what signal processing and other features are implemented. Chapter 4 is a detailed description of the RF front end that will generate and modulate the data onto the carrier. This section will mainly be design considerations and how the best performance was achieved. Chapter 5 covers what design the microcontroller portion underwent and will describe what it does in the system. Chapter 6 will detail the testing and any results from testing that is obtained. Testing will be carried out on breakout boards and on any designed boards that are manufactured throughout the thesis. Chapter 7 covers any complications that were noticed during the design and any future work that should be done to advance the project in the future.