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    25 April 1996, Volume 16 Issue 02 Previous Issue    Next Issue
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    RESEARCH OF ARRAY SYNTHESIS WITH PREDETERMINED BEAM SHAPES BASED ON IDFT ALGORITHM
    Jiang Yongquan(Electronic Department and AI&PR Open Lab, Shantou University, Shantou 515063)
    1996, 16 (02):  . 
    Abstract ( 2022 )   Save
    he array antennas with predetermined beam shapes have applications in the fields of satellite communication, remote sensing and synthetic aperture radar (SAR), etc. A new algorithm for array synthesis based on inverse Discrete Fourier Transform (IDFT) is proposed in the paper. This algorithm has the advantages of minor calculation and best calculating stability. It can make a flexible trade--off between the shaping accuracy in the main-lobe and the magnitude of the minor-lobes if a window function is used.
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    CALCULATION METHODS FOR ATMOSPHERIC DRAG PERTURBATION AND ERROR ANALYSIS
    Liu Yaying(Purple Mountain Observatory, Academia Sinica, Nanjing 210008)Rong Pengzhi(Shanghai Institute of Satellite Engineering, Shanghai 200240)
    1996, 16 (02):  . 
    Abstract ( 2068 )   Save
    n order to improve the accuracy of the prediction of satellite's orbit, the calculation methods of atmospheric drag perturbation are studied. On the basis of the principle of atmospheric drag perturbation this paper describes two methods: numerical method and combining both of analytical and numerical method. The error δp of the satellite's position in orbit due to various level (F10.7 of 150, 200 and 250) of solar activity and the model's error of 10%- 20% are analyzed for three kinds of upper atmosphere models: CIRA-1986, CIRA-1972 and DTM. The results show that: ① The effect of the solar activity level on the error δp is obvious. The error δp increases fast with F10.7 in case of given atmosephere model error. ② The error δp increases proportionally as the difference between the model and the reality increases. ③ The error a, due to the variety of atmosphere model is not noticeable in general, but when F10.7 is greater than 200 the difference between DTM model and CIRA model is very noticeable.
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    DISCUSSION ON RELATED TECHNIQUES OF SPACECRAFT ANTENNAS
    Wang Jueqi(Beijing Institute of Spacecraft System Engineering, Beijing 100086)
    1996, 16 (02):  . 
    Abstract ( 1741 )   Save
    This paper discusses the characteristics of spacecraft antennas and the relations between antennas and spacecraft system along with the related topics about antenna pattern and gain, the electromagnetic compatibility (EMC) and the computer aided design (CAD) of antennas.
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    STATISTICAL ANALYSIS OF VERTICAL SHEAR OF WIND
    Dong Shuanglin (Beijing Institute of Applied Meteorology, Beijing 100029)Li Linfan(Beijing Institute of Space Machine and Electricity, Beijing 100076)
    1996, 16 (02):  . 
    Abstract ( 2739 )   Save
    wing to the limitation of vertical resolution of observation data and different practical requirements, there are several different schemes and results for statistical analysis of vertical shears of wind. Therefore, how to analyze and use these schemes and results correctly become a very important problem to be solved urgently. This paper analyzed differential shear, mean shear for a layer with determined thickness, difference shear-the vertical shear of mean wind for a layer with determined thickness, and their differences for different functions as altitude. In this paper, effects of layer thickness, measuring mean time of wind, techniques of vertical interpolations of wind on the shears were discussed. The layer thickness depends on practical requirements, so vertical shear of wind is not a pure meteorological element.Besides, extremes of vertical shears of wind were estimated.
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    ELECTROMAGNETIC COMPATIBILITY PROBLEMS IN SPACECRAFT SYSTEM DESIGN
    Liu Jianxin; Tang Zequn(Beijing University of Posts and Telecommunications, Beijing 100088)(Beijing Institute of Spacecraft System Engineering, Beijing 100086)
    1996, 16 (02):  . 
    Abstract ( 2042 )   Save
    n this article, under the features of spacecraft system design, the EMC concept and its development are introduced. The electromagnetic environment of spacecraft is analyzed, and several EMC problems in spacecraft system design are pointed out. The content of EMC work during each phase of spacecraft development is put forward and it is emphasized that we must pay high attention to EMC of every sort of spacecraft.
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    CONCEPTUAL RESEARCH OF TELESCIENCE COMMUNICATION LINKS BASED ON CCSDS
    Cui Long; Zhang Eryang(National University of Defense Technology, Changsha 410073)
    1996, 16 (02):  . 
    Abstract ( 1727 )   Save
    o make effective use of the limited resources in space stations, the concept of telescience is presented. The various scientific experiments under microgravity environment in space stations need to communicate with ground interactively. The Consultative Committee for Space Data Systems (CCSDS) developed a series of standards for such communication links. This paper emphasizes the discussion on the requirement of communication links by telescience, the model of space data systems suited for telescience experiment, the framework of onboard and ground communication systems.
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    LOOK INTO COMPUTER VISION DEVELOPMENT FROM ACCV'95
    Ye Peijian(Chinese Acadmy of Space Technology, Beijing 100081)
    1996, 16 (02):  . 
    Abstract ( 1557 )   Save
    In this paper, the author gives an overview of the Second Asian Conference on Computer Vision (ACCV' 95), presents the research results on computer vision and related subjects, discusses the theoretical problems and practical applications. Also, the author put forward his point of view and proposal concerning how to develop computer vision in CAST.
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    INVESTIGATION AND APPLICATION OF TWO THERMAL CONTROL COATINGS ON THE THERMAL BARRIER OF COMMUNICATION SATELLITES
    Weng Ruqin; Wang Zhenhong;Chen Xinbiao(Shanghai Institute of Ceramic, Chinese Academy of Science, Shanghai 200050)
    1996, 16 (02):  . 
    Abstract ( 1827 )   Save
    n this paper the composition, technique and properties of two coatings GD2 and GD2A were described and the factors which influence the properties were also discussed. Experimental results showed that the properties of two coatings were stable and they reached the requirements of the thermal control design. Two coatings were used successfully on thermal barrier of the communication satellites.
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    80C31 SEU SENSITIVITY EVALUATION
    Tang Min; Zhao Dapeng; Meng Qingru; Wu Zhiyu; Yu Qingkui (Beijing Institute of Satellite Environment Engineering, Beijing 100029)Lan Zengrui(Shanghai Institute of Spacecraft Engineering, Shanghai 200240)Cheng Ertong;Luan Binghui(Shanghai Institute of Tech
    1996, 16 (02):  . 
    Abstract ( 1667 )   Save
    Microcontroller 80C31 single event upset (SEU) sensitivity evaluation test is performed by using heavy ions from Tandem Van-de Graff accelerator.According to the error cross section versus LET curve, bit upset rate of 80C31 on geosynchronous orbit is estimated.
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    PARALLEL CORRELATIVE FRAME SYNCHRONIZER BASED ON MICROPROCESSOR
    Yu Yucai(Beijing Institute of Satellite Information Engineering, Beijing 100080)
    1996, 16 (02):  . 
    Abstract ( 1627 )   Save
    frame synchronizer of variable rate and variable frame length using parallel correlative technique is introduced in this paper. Major frame and subframe are synchronized by using the combining method of hardware and software based on 8031 microprocessor. According to theoretical calculation, error threshold, check frame number a and protection frame number 5 are obtained. The frame synchronizer was used successfully in receiving communication satellite PCM telemetry data.
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