RF-based triangulation system utilized as a tracking system on a model helicopter

This project was created on base of a need to replace a model helicopter's GPS system, with a solution that didn't rely on any type of GPS signal. A helicopter competition amongst international universities dictated some regulations on use of a model helicopter and prohibited the use of GPS or GPS-assisted location finding systems. As an important subsystem to the helicopter's avionics system and flight computer, this project was started right away to develop a solution that could replace the GPS unit onboard of the helicopter. Part of the initial extensive research was to come up with a quick and implementable design which could be tested prior to vehicle integration. Limitations were enforced by the helicopter which had already been purchased, limiting the amount of electrical power available to such solution, and the weight of this subsystem, allowing for proper liftoff. Three different RF solutions were considered, including a RF phase measurement, Received Signal Strength Indicator (RSSI), and RF signal roundtrip travel time. These methods were studied in detail, keeping in mind the project budget and short schedule allotted for this development. The decision was made to construct a system using a SoftCore microprocessor in an FPGA to control the modems and perform calculations necessary for triangulations. Various RF modems were also studied and researched for a technology suitable for this effort. This paper discusses all the phases of the design, its capabilities as well as the limitations. Recommendations are also made for improving the system as future work. The mathematical Methods are discussed as well, demonstrating the triangulation method which was used