Implementation and verification of a real-time high-precision initial pointing algorithm for LEO satellite laser terminals

Abstract

The rapid advancement of Low Earth Orbit (LEO) satellite Internet constellations has positioned inter-satellite laser communication links as a critical technology for space information networks, owing to their high bandwidth capabilities, resistance to interference, and the absence of frequency allocation requirements. However, the high relative speeds of LEO satellites and the narrow divergence of laser beam present significant challenges for the initial acquisition of laser terminals. To overcome these issues, this paper introduces a high-precision, real-time initial pointing algorithm for LEO satellite laser terminals. The algorithm employs J2 model-based orbit extrapolation using real-time orbital elements to eliminate position prediction errors, applies attitude interpolation to generate high-frequency attitude data from sparse sensor samples, and constructs a refined pointing instruction interpolation model based on a second-level benchmark to reduce onboard computational load while ensuring real-time responsiveness. On-orbit test results demonstrate that the root-mean-square (RMS) pointing error of the laser terminal guided by the proposed algorithm achieves an overall accuracy better than 1 mrad. A 400 MHz onboard processor supports 50 Hz precision-maintaining pointing calculations, satisfying the system’s timing requirements.