Unambiguous AOA estimation using SODA interferometry for electronic surveillance

Computationally fast AOA estimation using sparse large aperture arrays for electronic surveillance

“…Since the measured phase delays are ambiguous, an ambiguity resolution method is required to perform unambiguous AOA estimation [2].…”

“…The steering vector contains the spatial phase delays corresponding to the chosen steering angle, θ s , and may be written as v (θ s ) = e jψ11(θs) e jψ21(θs) · · · e jψ K1 (θs) T , (15) where the phase delays are given by (2). The cross spectral matrix, or covariance matrix, is a K × K matrix defined as…”

“…Large apertures are required for high accuracy AOA estimation, but since there are a limited number of independent receiver channels, practical interferometers are often implemented using sparse, non-uniform array geometries, or "long-baseline interferometers". In [1,2], it was shown that a secondorder difference array (SODA) can be used by the SODA interferometer to perform unambiguous AOA estimation in a computationally efficient manner. Higher accuracy AOA estimation can also be obtained by refining the SODA AOA estimate using the SODA-Based Inference (SBI) interferometer.…”

“…This paper considers the speed and accuracy of the SODA and SBI interferometers [1,2] in the context of sparse large aperture arrays and compares their performance to the conventional phaseshift beamformer and MUSIC algorithm. The performance of the algorithms will be compared through simulation and verified using experimental data.…”

Ultrawideband Discharge Source DOA Estimation Method Using Multiple Baseline Wideband Time-Domain Interferometry with Hilbert Transform

“…Over the past decades, narrowband interferometry has been developed and implemented in radiation source locating, especially in lightning locating field [8][9][10][11]. Nevertheless, angle ambiguity is an inevitable problem in narrowband interferometry, and many algorithms have been proposed to eliminate the ambiguity [12][13][14]. However, the radiated EMPs of lightning and other discharge sources is a wideband signal, the frequency of which ranges from a few kHz to several GHz [1,6].…”