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Laser communication has become the main driving force for the development of modern wireless optical communication technology with the characteristics of large communication capacity, good concealment and good directivity. Acquisition, pointing and tracking system which is refer to as the APT system is the key technology to the laser communication, and the detection and processing technology is one of the key technologies of APT system. The effect of scintillation and laser spot drift caused by atmospheric turbulence seriously affects the laser spot positioning accuracy of laser communication APT system, which will affect the performance of laser communication system. It is very important to choose the appropriate spot pre-processing method and the best method to improve the positioning accuracy of laser communication system. An ideal spot image with known center coordinates was generated artificially and the MATLAB was used to simulate the atmospheric turbulence to make the laser spot close to the real atmosphere. Chosing median filtering and mean filtering method to the denoising pretreatment to get filtered image. Using iterative threshold method to obtain the binary image. Through 3 common spot positioning method like the gray centroid method, circle fitting method and the Gaussian fitting method to calculate the centroid of the binary image. After getting the central coordinates, the results were compared and analyzed. Experimental results showed that mean filtering is better than median filter to filter noise of the laser spot. Compared with other methods, the centroid accuracy obtained by the gray centroid method had larger deviation due to the process of filtering the noise was not completely suppressed. The laser spot center calculating by the Gaussian fitting method were with higher positioning accuracy. According to the calculation results, the applicable conditions of different spot location algorithms were given.
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