AoA Estimation Using Hybrid Phase-Amplitude Interferometry for LEO Spaceborne SDR Systems

This paper presents a two-dimensional Angle of Arrival (AoA) estimation system for compact Low Earth Orbit (LEO) platforms operating in the X-band. Severe size, weight, and power (SWaP) constraints restrict antenna dimensions, inducing phase-wrapping ambiguities. To overcome this, a Hybrid Ambiguity Processor (HAP) is applied, which deterministically fuses phase interferometry with amplitude comparison using a compact 2x2 orthogonal baseline array. Experimental validation using a software-defined radio (SDR) testbed under emulated orbital dynamics demonstrates the system's capability to successfully resolve ambiguities, accurately characterizing the spatial incident wavefront across the system's operational field of view.