Probability Descent-Based Equivalent Spot Scanning for Satellite Laser Acquisition in Elliptical Field of Uncertainty

Intersatellite laser communication has emerged as a critical technology in modern satellite networks due to its high data rate, low-power consumption, and robust antijamming capabilities—attributes that are particularly important in the era of Big Data. The establishment of reliable communication links depends on precise pointing, acquisition, and tracking (PAT) technology. PAT serves as the core of the electronic control loop in laser terminals, acting as the optical feedback input for the system; by correcting the elliptical FOU, it enhances the effectiveness of the control loop algorithms in intersatellite laser communication. However, existing research into the field of uncertainty (FOU) in PAT systems has significant limitations. Traditional PAT models typically assume a circular FOU that deviates from on-orbit conditions, conventional spiral scan (CSS) method has defects when dealing with anisotropic FOU, suboptimal scan path planning and suffer from inefficiencies such as low spot energy utilization. To address these challenges, this article proposes the equivalent spot region truncated spiral scan (ERTSS) method, which partitions the elliptical FOU into weighted scan regions and integrates a composite truncated spiral scan strategy to enable efficient path correction. Monte Carlo simulation shows that under typical actual on-orbit working conditions, the ERTSS method can effectively shorten the acquisition time by up to 78.88% compared with CSS, providing an effective solution for optimizing PAT systems in satellite laser communications.