Research On Precise Positioning Algorithm Of Satellite Laser Communication Four Quadrant

Satellite laser communication is a kind of wireless communication mode which takes the optical signal as the carrier of transmitting information and directly transmits in free space or atmosphere.Basically,all satellite laser communication terminals are captured and tracked using alignment,capture,tracking?PAT:Pointing Acquisition Tracking?techniques.PAT technology is one of the key technologies for establishing reliable laser communication link in satellite optical communication system,and the unit of location detection of incident light spot is an indispensable part of PAT system.When detecting and locating the incident laser spot position,it is especially important to select the best suitable photoelectric position detector.Because the four quadrant photodetector compared with PSD and CCD,it has high detection sensitivity and spatial resolution,spectral and wide dynamic range,fast response to make it more and more is applied to light spot position detection system.In the satellite laser communication system,the beacon light source is changed from the 800 nm wavelength to the 1550 nm wavelength.The detection using the four-quadrant detector can combine the signal light and the beacon photo into one,thereby realizing the non-beacon?narrow beacon?capture tracking.The structure is light,and the positioning accuracy of the QD directly determines the capturing performance of the system,and eliminating the Angle between them and improving the coaxial consistency of the system.In this paper,the application and development of QD in laser spot location detection system at home and abroad are investigated,and the research status of QD spot center positioning algorithm and factors affecting the accuracy of QD detection and positioning are introduced in detail.The problem that the positioning accuracy of the existing algorithm is not high or has high positioning accuracy but the sampling speed is slow and the noise channel has a great influence on the positioning accuracy of QD is studied.This topic mainly studies the working principle,position detection principle and performance evaluation parameters of QD;focuses on the influencing factors of QD positioning accuracy,and introduces several positioning calculation methods for obtaining spot position coordinate information by QD.In order to improve the sampling speed and spot position detection accuracy and compensate the errors caused by noise,channel and other influencing factors,the polynomial fitting and localization algorithm is deeply studied.Based on this,a piecewise orthogonal polynomial fitting algorithm and cubic spline are proposed.A hybrid localization algorithm based on interpolation and orthogonal polynomial fitting,and numerical simulation analysis using MATLAB software,The simulation results show that the maximum position detection error of the new algorithm near the center of the detector target surface is of the order of 10^-5 mm.The experimental results of displacement test show that the maximum detection error of the new algorithm is reduced by 80.84%compared with the traditional direct localization algorithm,which verifies the rationality and feasibility of the piecewise orthogonal polynomial fitting method and cubic spline interpolation fitting method.