Optical Undersampling-Based Estimation of Frequency and DOA for Multi-Band Signals

This paper presents a joint frequency and direction-of-arrival estimation method based on an optical frequency comb combined with a uniform circular array. By leveraging optical undersampling, the system captures high-frequency signals using low-speed ADCs while preserving essential spectral features. A novel dictionary construction strategy is introduced, combining frequency-folding indices and azimuth angles to significantly reduce computational complexity. Furthermore, a frequencydomain covariance model and eigen-decomposition approach are employed to enhance estimation robustness under low signal-tonoise ratio conditions. Simulation results demonstrate that the proposed method achieves high estimation accuracy and strong noise resilience across a broad range of frequency, validating its effectiveness for signal processing applications.