Photonic-Assisted Multi-Antenna Frequency-Spatial Compressed Sensing Array for Joint Frequency and DOA Estimation

A photonics-assisted compressive sensing (CS) array system based on uniform linear array (ULA) for wideband sparse radio frequency (RF) signals acquisition and direction of arrival (DOA) estimation is proposed. Each branch of the system consists of two cascaded Mach-Zehnder modulators (MZMs), an integrator, and a low-rate analog-to-digital converter (ADC). The modulated pseudo-random binary sequence (PRBS) is the same across each coherent branch so that the simultaneous orthogonal matching pursuit (SOMP) and the orthogonal matching pursuit (OMP) algorithm are used to estimate the frequency and DOA. Since the construction of measurement matrices for each of the estimated frequencies to independently estimate the DOA, which avoids the problem of matching between frequency and DOA. The introduction of multiple coherent branches not only enables the estimation of DOA but also improves the accuracy of the frequency recovery. The frequency estimation accuracy of multi-tone signals reaches 0.01 GHz, and the angle estimation accuracy reaches 1$^{\circ }$ at the signal-to-noise ratio (SNR) of 10 dB in the simulations and experiments, which demonstrate the feasibility of the proposed method in joint frequency and DOA estimation.