The Simulation Of ATP Alignment Features In Atellite-to-ground Laser Communication

Quantum communication combined the traditional communication science and the quantum mechanics, compared with the classical communication with high confidentiality and security. Free space especially satellite-based quantum communication gets rid of the distance constraints of the fiber also provided an effective way to build world coverage quantum communication network. Since quantum beam divergence is only dozens of micro-radians of the quantum communication system between the satellite and the ground, the establishment and keeping of the communication link is the important and difficulty point of the system.The achievement of the quantum communication link between satellite and the ground is based on the high accuracy acquisition pointing tracking system. In this paper starting from the main factor which influenced the ATP alignment accuracy, researched and emulated the algorithm about the azimuth elevation feature, advanced targeting feature, the base lost correction features and atmospheric refraction feature during ATP alignment.The main research work and innovation of this dissertation are as follows:(1) Modeled the coordinate system of the quantum communication systems between the satellite and ground station, derived a set of algorithms about conversions between coordinates of quantum communication system. Based on these works, calculated the azimuth and elevation angles using related orbit prediction data. Discussed the satellite and ground alignment problem. Also handled the alignment problem of single payload and double payload separately. Finished the numerical simulation about the algorithms derived. Using the simulation software STK (satellite tool kit) completed the validation of the algorithms.(2) Researched the advanced targeting issues which caused by too high relative speed between satellite and ground. Derived the algorithm of calculating the advanced targeting angle, and analyzed the feasible methods to solve advanced targeting issue in engineering. Also analyzed the transmission problem of the polarized base vector, started from the transmission channel of the quantum communication. Analyzed the factors which caused polarized base-vector change. Calculated the change in direction about the polarized base vector among the process of the quantum communication between satellite and ground. Also ran the related software emulation. (3) Studied the air deflection phenomenon which caused by the change of the refractive index. Combined the relationship of refractivity and communication wavelength and altitude, emulated the deflection angle of the atmosphere. Simulation results can provide some suggestions for the ATP design.