Azimuth and Elevation Estimation With Rotating Long-Baseline Interferometers

The performance of most multi-channel 2-D direction-of-arrival (DOA) estimation array systems are very sensitive to various model imperfections, while static single-channel interferometers can only realize 1-D direction estimation, and they have to trade off between the DOA estimation precision and the non-ambiguity scope. This paper establishes a system framework for 2-D DOA estimation with a phase-only rotating long-baseline interferometer (RLBI), whose baseline is much longer than the signal wavelength. The RLBI collects interleaved pulse phase-difference measurements of multiple emitters when it is rotating with a uniform angular speed, and the measurements are then exploited to estimate the number and 2-D directions of these emitters. Deep insights are given into the DOA estimation properties of the RLBI system, and the spatial sparsity of the emitters is exploited to propose a source number and 2-D DOA estimation method, named Direction estimation via Spectral orthogonal Matching Pursuit and DeSoMP for short. DeSoMP is implemented based on a spectral data vector obtained via particular transformations from the original phase measurements and do not need to de-interleave the phase measurements of different emitters beforehand. The feasibility of the established RLBI system framework and the performance of the proposed method are demonstrated with simulations.