Study On APT Technology Of Space Optical Communication Based On The Internet Of Things

As one of the strategic commanding points of technology and economic development in the world,the Internet of things has become an important tool for the construction of information society in all developed countries.With the spread of its applications in intelligent transportation,smart grid and video surveillance,the demand for the terminal access rate of the Internet of things is increasing.The traditional radio mode has been unable to meet the needs of the reality.The network transmission technology based on space optical communication is flexible,and its communication rate is greatly improved.It is a new technology to realize self organizing communication network based on the high speed Internet of things,and the study of it is very meaningful.The APT(Acquisition,Pointing,Tracking)system is one of the key issues that need to be solved for space optical communication.Due to the failure of positioning in traditional GPS/INS system when it is shielded and in view of the feature of the Internet of things,this paper proposes the use of WiFi positioning system instead of GPS/INS positioning system to complete the acquisition of position information of both sides in the APT capture process,and two key technologies(initial acquisition and spot detection)of the APT system were studied.First,the overall scheme of APT initial capture under WiFi positioning is proposed.The principle of WiFi positioning,three-dimensional location algorithm and the coordinate conversion process in initial acquisition are introduced,and the uncertainty region obtained by initial acquisition testing within 200 m is 13 mrad,At the same time,the average acquisition time corresponding to different scanning modes is calculated.Besides,Matlab software is used to simulate and analyze the positioning errors that affect the initial acquisition of APT.In view of the spot image captured by the APT system in different background,the floating threshold method combined with the circular fitting method is used to detect light spot.Multi group of spot detection tests are carried out under three representative conditions of clear day,cloudy day and night.The results show that the location and contour of spot can be quickly and accurately extracted by the spot detection method.