Direction Finding for Software Defined Radios with Switched Uniform Circular Arrays

Accurate Direction of Arrival (DoA) estimation is critical for robotics and communication, but high costs and complexity of coherent multi-channel receivers limit accessibility. This work proposes a cost-effective DoA estimation system for continuous wave (CW) signals in the 2.4 GHz ISM band. A two-channel software-defined radio (SDR) with time-division multiplexing (TDM) enables pseudo-coherent sampling of an eight-element uniform circular array (UCA) with low complexity. A central reference antenna mitigates phase jitter and sampling errors. An enhanced MUSIC algorithm with spatial smoothing addresses light multipath interference indoors and outdoors. Experiments in an anechoic chamber validate accuracy, while real-world tests confirm robustness in multipath environments. With 5 Hz DoA updates and post-processing to enhance tracking, the system provides an accessible and reliable solution for DoA estimation in real-world environments.