The Research On Weak Signal Detection And Data Processing Technology Based On QD

Space optical communication is a cutting-edge and hot research topic in the field of communication.The ATP system is one of the core technologies that ensure the stability and reliability of satellite laser communication links.The detection accuracy of the detector for the angular position of the beam significantly affects the performance of the Acquisition,Tracking and Pointing(ATP)system and is crucial for achieving high-performance ATP technology.The long-distance space optical communication system without independent beacon has the characteristic of detecting weak signals,but the signals received by the detector are affected by background noise,scattering noise,thermal noise,and other factors.This seriously affects the detection accuracy of the system for the spot angle position,which is one of the problems that must be solved for high-performance long-distance space optical communication.To address this issue for high-precision spot angle position detection based on quadrant detector(QD)under low signal-to-noise ratio conditions,this thesis conducted research through theoretical analysis,simulation analysis,and experimental verification.Based on the analysis of the research dynamics of space optical communication and weak signal detection technology both domestically and abroad,and in light of the research goal of improving the transmission performance of wireless optical communication links,this thesis analyses a mathematical model for the position detection accuracy of a QD for the problem of detecting the angular position of a light spot under low signalto-noise ratio conditions.Under low signal-to-noise ratio conditions,the thesis carries out simulation analyses on the received signals modulated by intensity,using FFT spectral detection,time-reversed deconvolution spectral enhancement,cross-correlation spectral enhancement,and Kalman filtering,and designs a data processing scheme based on cross-correlation spectral enhancement and Kalman filtering.The thesis conducted simulation analysis of the spot position detection scheme based on cross-correlation and Kalman filtering using MATLAB simulation platform and VIVADO platform,thereby verifying the feasibility and effectiveness of the proposed scheme.The verification results demonstrated that performing cross-correlation and Kalman filtering on the input signal effectively suppressed noise and obtained more accurate detection amplitudes.Based on the above theoretical research,a testing and verification platform was designed and constructed to conduct experimental validation of a signal processing scheme based on cross-correlation spectral enhancement and Kalman filtering.The platform calculated the output optical intensity values before and after algorithm processing and compared them with the direct detection method.It achieved improved accuracy in spot position detection under low signal-to-noise ratio conditions,demonstrating the feasibility and effectiveness of the algorithm.