Direction-of-arrival estimator using array switching on software defined radio platform

In this work, a 360 degrees direction-of-arrival (DOA) estimator using array switching technique is implemented on a software defined radio (SDR) platform. The estimator includes a square antenna array comprising 16 dipole antennas, which is segmented as four 4-element uniform linear arrays (ULA). All 16 antenna elements are connected to RF switches and then connected to four RF receivers. By configuring the switch status via software defined radio, one of the ULA is activated for DOA estimation using multiple signal classification algorithm. The well-known inaccurate DOA estimation near the end-fire of a ULA is avoided in this design. Each ULA only estimate signal source within its broadside ±45 degree azimuth. By switching the four ULA, 360-degree azimuth is covered. Because the four receivers are phase incoherent, this design includes a phase calibration function. Outdoor measurements show that the implemented system can estimate the DOA of impinging signals with high accuracy even with some multipath reflections. The system is very flexible and can easily reconfigure the shape or element-number of antenna array by modifying the corresponding code on SDR platform.