Direction Finding System using an N-Channel Software Defined Radio Implemented with a Phase Interferometry Algorithm

Providing portable and accurate radio frequency direction finding capability remains non-trivial, as estimating the direction of signals at a distance becomes very difficult when both systems are not stationary. Improvements in this area could provide significant advantages for both commercial and military systems. This paper presents a traditional radio signal direction finder implemented with a four-channel coherent receiver, GNU Radio software for the signal processing and a four-dipole antenna element array. The signals are received by the four-channel software defined radio (SDR) using a four-antenna dipole antenna array and processed through GNU Radio software. Within GNU radio software we are implementing an interferometry algorithm, through which we present the ability to determine the arrival direction of a signal based on a quadrant (45, 135, 225, 315). We further resolve the ability to visualize the signals by providing a compass which displays arrow directed to the quadrant of the signal. We will expand on our work by providing potential future improvements that would continuing to make the device more accurate and portable.