Accurate Real-Time Laser Spot Locating Based on Template Correlation in Intersatellite Laser Communications

In intersatellite laser communications, the centroiding accuracy of a laser spot is crucial for maintaining steady communication links. However, the systematic error introduced by discrete sampling restricts further improvement of centroiding accuracy when choosing algorithms that are widely used in engineering. Additionally, the ultrahigh computational complexity and multiple-step iterations of the Gaussian fitting (GF) algorithm are unsuitable for real-time implementation, even though the algorithm can achieve the highest centroiding accuracy. In this study, we propose a laser spot centroiding algorithm based on template correlation to simultaneously satisfy the requirements of real-time performance and accuracy. The proposed algorithm evaluates the central location of a laser spot by obtaining the index of the maximum Pearson correlation coefficient (PCC). Simulations performed under different conditions reveal that the proposed algorithm is robust against the interference of background noise and the bad pixels. Moreover, experimental verification is performed based on the implementation on a Field-Programmable Gate Array (FPGA) in real-time, meanwhile its accuracy is on the same level as that of the GF algorithm and better than those of other widely-used algorithms. Therefore, the proposed algorithm is suitable for accurate real-time locating of laser spots in engineering applications of the intersatellite laser communications.