The Research On Acquisition And Tracking Technologies Of ATP System In Optical Intersatellite Communications

Optical intersatellite communications will be an important element in the future satellite communication infrastructure. An optical intersatellite communication system must be capable of high accuracy line of sight under disturbance in satellite environment for reliable communications, as a consequence, the acquisition, tracking and pointing (ATP) are critical and difficult issues in optical intersatellite communications. Tracking system is the kernel of implementing ATP functions, and rapid acquisition is basic requirement in establishing the optical links. So, it is necessary for researching acquisition and tracking techniques in optical intersatellite communications.Based on the brief introduction of the concepts, key techniques, development trend, and subsystem of optical intersatellite communications and ATP techniques, the acquisition and tracking technique, fine tracking control algorithm and fine tracking demonstration system are studied in this dissertation.Firstly, after discussing the acquisition scenarios, acquisition method, and scan pattern in acquisition technique of optical intersatellite communication, the acquisition probability is studied. Through analyzing the scan area coverage probability, the overlap factor calculation method is proposed. By this method, the acquisition probability can be increased. Based on the analysis of detection probability, the acquisition optimum threshold current and detection probability are obtained under the condition of different threshold-to-noise ratio and signal-to-noise ratio. Then, acquisition link simulation is presented.Secondly, the tracking error and the control structure of tracking technique in optical intersatellite communications are studied with emphasis. On the basis of the statistic model of tracking error, that tracking error effects on system performance is studied. In which, the optimum relationship between beam width and tracking error is obtained with given the burst error of system. And that, the optimum relationship between beam width, tracking error and bit error rate in IM/DD communication is also proposed. Based on this optimum relationship, the minimum transmitter power which can satisfy the optical link budget requirement is calculated. In addition, the source of tracking error, such as, detector error, satellite platform vibration and vibration rejection methods are analyzed. In tracking system structure research, the...