Joint DOA and Frequency Estimation Method of Multiband Signals With Single Optical Frequency Comb

Traditional electromagnetic signal receiving techniques require high Nyquist sampling rates, making it difficult to achieve rapid frequency and direction of arrival (DOA) estimation for multiple non-cooperative signals over a wide bandwidth. Optical frequency comb (OFC) based sampling reception techniques can simultaneously down-convert multiband signals into the same low frequency region, thus addressing this challenge. However, due to the under-sampling process, the original frequency information is lost, further rendering the phase information unavailable. To overcome these limitations, this paper proposes a single OFC driven, optical delay controlled uniform linear array signal reception architecture. By introducing different lengths of optical fiber delay before each antenna channel, the proposed system enables joint carrier frequency and DOA estimation of multiband signals under sub-Nyquist sampling conditions. The method constructs a virtual array in the frequency domain using the autocorrelation matrix, and jointly solves for the down-converted frequency index and the DOA. It features high phase accuracy, low sampling complexity, and strong adaptability to wideband signals, while avoiding the increased system complexity and inter-channel matching difficulties associated with existing multi-comb sampling techniques. Simulation results show that within the 0–9.8GHz range, the proposed system achieves a frequency estimation error of 3 kHz and an angular error of 0.67°. Experimental measurements demonstrate an average frequency estimation accuracy of 50 kHz and an average DOA estimation accuracy of 0.7°.