The Design And Implementation Of Automatic Measurement For Pointing Precision Of Deep Space Exploration Antenna

In deep space exploration,large-caliber antennas are indispensable radio transceiver equipments in communication system of deep space tracking telemetering&control system and ground application system.Pointing precision is one of the important performances to evaluation the directivity of deep space exploration antenna.This paper mainly investigates the design of computer-aided automatic measurement system to accurately measure the antenna pointing precision.Firstly,the pointing precision measurement principle and its corresponding arithmetic of deep space exploration antenna are analyzed in this paper.Afterwards,the computer-aided automatic measurement system is described according to the requirement of measurement method.Afterwards,computer automatic measurement system is described according to the requirement of measurement method.The principle and system composition of the system are described in detail.Then,the detailed design method of the key software module of the automatic measurement system is concentrated,including the coordinate conversion module,the measurement&control module,and the data collection module.The system has the characteristics of complex composition,multi-interface form and high measurement precision.To eliminate or minize the measurement errors as small as possible,in the hardware and interface we have taken several strategies,such as improving the hardware configuration and establishing private network for communication etc.In software design,firstly,we take a variety of ways to ensure data accuracy,precision and correctness.We use the lastest celestial motion theory and astronomical constants to enture the accuracy of the calculation model and parameters and use "Symmetry" to find the exact time and angle of the antenna alignment source to enture the correctness of the data.Secondly,using the antenna objective angle which is three seconds ago to eliminate the network transport delay,introducing feedforward technology to improve antenna's control precision;Third,applying multithreading technology which based on the Widows media flow control to enhance the timing precision.Finally,the error sources of the computer-aided automatic measurement system are analyzed,including the timing error,the sampling error,the theoretical calculation error,and the command delay error.All these errors are quantitatively analyzed.Meanwhile,the application of this system on the 50m antenna located in Beijing Miyun is introduced.It is found that the system could meet the requirements of the measurement application.The measurement system we discussed in this paper is based on practical engineering projects.This method has been implemented successfully in 50m and 40m antenna for lunar exploration project,and the two antennas have successfully completed the tasks of high precision orbit determination and data receiving for Chang'e satellites.