Denoising approach for the beacon light spot in satellite-to-ground laser communication

In satellite-to-ground laser communication, beacon beam transmission faces challenges such as signal attenuation, atmospheric turbulence-induced distortion, and detector thermal noise, all of which degrade alignment and tracking accuracy. To address these issues, this paper proposes a wavelet transform-based denoising method that incorporates a novel threshold function, to our knowledge. This approach enhances noise suppression while preserving the edge details and energy distribution of the light spot image, thereby minimizing distortion. Experimental validation employed a three-layer atmospheric turbulence phase screen model to simulate Gaussian beam propagation over a 20 km distance at an 800 nm wavelength. Evaluations based on the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM) demonstrate that the improved algorithm achieves superior denoising performance compared to conventional methods, offering a robust and real-time solution for enhanced beam alignment in satellite-to-ground links.