Study Of Bidirectional Acquisition Technology In Intersatellite Optical Communication

Intersatellite optical communications (IOC) holds a potential performance edge over microwave (RF) communications in terms of higher data rates, smaller terminals and low probability of intercept. Pointing, acquisition and tracking (PAT) of IOC is a desiderated key technology. is used to establish laser links and recovery interrupts, and run out as soon as possible. The choice of acquisition methods is a key point of study. In fact, in despite of control precision of the satellite platform is incessant improving in the IOC process, due to the limit of effective load and terminal components, augmenting angle field of the acquisition beacon beam and the detector directly can't compensate the errors of the satellite gesture and orbit. Therefore we must adopt bidirectional acquisition technology under the most of instances.On the base of acquisition study with single terminal, this paper brings forward two bidirectional acquisition methods. At the beginning, the process of two methods was particular introduced, and theory models were established, respectively mathematics of acquisition probability and average time were given. Then the optimal scan fields of two methods were given. Under the request of the general platform capability and the certain acquisition probability, the scan field of two terminal need be equal for method, the detector field of terminal A need be as small as possible and the scan field of terminal B need be as large as possible for method 2. At one time parameters of the satellite influencing the bidirectional acquisition were analyzed, The influence of fixed offsets(errors of terminal gesture and satellite orbit and so on ) is main factor in the acquisition, while that of random offsets(errors of the vibration on the satellite) is accidental and can be compensated by increasing the scan overlaps.On the foregoing analyses, bidirectional scan acquisition simulation model was built by the soft Matlab/Simulink, the computer simulation experiments of the acquisition with different parameter was operated using Monte Carlo method. On the basis of analyzing simulation result, method 1 was improved on multi scan. The optimal single scan field and optimal scan times of the multi scan were given, and the capability of the improved method advanced largely. As the result of experiments, the request of the acquisition probability being more than98%,for the improved method 1 the average acquisition time is less than 3min when the platform control error is less than 5.7mrad, and the method is the optimum when the error is less than 3.3mrad; for method 2 the average time is less than 3min when the platform control error is less than 7.5mrad, and the method is the optimum when the error is more than 3.3mrad.While simulation experiments also proved the correctness of theory model and analysis.The study of the paper holds actual meaning for the choice of IOC acquisition methods and the design of acquisition system parameters. It can be consulted and used for reference for the design and develop of IOC acquisition system in the future.