| China Seismo-Electromagnetic Satellite (CSES) is the first satellite in China which aims to research ionospheric characteristic and seismoelectromagnetic effects in ionosphere, and will be launched in 5 years. The satellite ground application system (GAS) is necessary part in satellite project developing. In order to ensure satellite trouble-free operation, some researches on ground application system have to be carried out. Based on the urgent need of the project approval for China Seismo-Electromagnetic Satellite (CSES), this paper has made some researches on the key technology of the ground application system (GAS) under the conditions that there is no ripe experience to learn at home and the critical information is hard to obtain abroad.If interference is produced when data are transferred to ground receiving stations, the detection data will be influenced and the layout of ground receiving stations will be restricted. Therefore, firstly, the doubt that the data is disturbed by the downlink is excluded from the perspective of data application, ionospheric characteristic, analog simulation and test. After eliminating the doubt of interference caused by downlink, the layout of ground receiving stations is designed and put forward. The data-processing and result analysis are carried out in above courses. The outcome and conclusion of above researches are important reference for development of CSES and its ground application system.The main work of this paper is as follows:(1) The exiguous and required data and information are collected and analyzed.The data which can be used in the paper is less. Some vital data and related information about electromagnetic satellite and its ground application system are collected, and then analyzed comprehensively. It lays the foundation for research in this paper, and accumulates experience for the development of CSES in the future.(2) The problem that whether the data is disturbed by the downlink is studied thoroughly. And some advices to avoid the downlink disturbance are presented.In this paper, the data of"Double Star"are applied to the study of that whether the data is disturbed by the downlink for the first time. Combine with the analysis of DEMETER data, the doubt that the data is disturbed by the downlink is excluded from the perspective of data application. And then the characteristics of the radio propagation in ionosphere are analyzed and the impacts on X band propagation link caused by ionized layer are estimated, and the results show that the ionized layer does not disturb the data downlink each other. According to the preliminary index of the CSES, the EMC simulation is calculated between digital transmitters and sensors on satellite, and the conclusion is drawn that the EMC is satisfied between digital transmitters and sensors when the IMSC is at least 1.2m away from the digital transmitter's power line. Moreover, the ongoing X band digital transmitter is used to test the EMC, and which show that the digital transmitter's power line probably causes conducted interference to sensors and harmonic component probably disturb the GPS occultation dual frequency receiver if the frequency flow is improperly designed. However, all the problems above can be avoided by taking some measures in the process of designing the digital transmitter. Based on the analysis of all above results, some related solutions to avoid the data downlink disturbance are presented as follows: scientific layout of the payloads on satellite, the EMC and indicator design of the transmitter, compatibility experiment between transmitter and sensors and the operational control command adjustment etc.According to the problem that whether the data is disturbed by the downlink, some methods are used to process the study such as exploration data analysis, electromagnetic waves propagation analysis, and the EMC simulation test. This is one of the most effective methods to solve the problem. Moreover, it is helpful to select ground receiving stations optimally, and the solutions to avoid the data downlink disturbance provide important references to the research and development of the CSES practically.(3) The layout solutions of ground receiving stations are presented according to the industry needs of CSES.First, the constraints of the ground receiving stations layout are analyzed, and the priority level is work out statistically based on the questionnaire. The related data are collected and stored in database. The relationships among constraints are cleared. Based on the relationship and constraints, the mathematical model of optimal location is built. Using GIS spatial analysis and orbit simulation, the model of optimal location is analysis calculated. The specific layout solutions are as follows:①single station model: Beijing is the first choice in single station model, constructing new ground station or using already existing ground are adopted to receiving data;②symmetrical model: building a new station in area A with the extent between 91°20′34″E～94°36′27″E and 33°17′20″N～34°29′21″N and the other area B in YuChen;③V-type model: building three stations in Kuerle, SuiHua, ZhaoQing;④four stations model: The best layout group is LaSa, SuiHua, XinFengjiang, Ku'erle. Then according to the calculation procedure of the solutions, a general station selection flow for the CSES is put forward. In light of current situation, there is no such systematic research about the ground receiving station selection. The research work in this paper is carried out for the first time in China and provides important references to the decision makers. (4) The plasma observation models in ionosphere are built and analyzed.A global observation data statistic model of Ne, NH+, NHe+, NO+ is built and its characteristic is analyzed. The spatial and temporal statistics is done by calculus of interpolation on the different plasma parameter derived from DEMETER for three consecutive years. The global distribution character of the different ion is further comprehended. The revisited orbits in an area for one year is processed and analyzed by different geomagnetic seasons. The analysis results are well complementary for current research which mainly focused on the research of TEC in ionosphere. This paper enriches the former study to some extent.(5) The abnormal phenomena in ionosphere before earthquakes are explored and analyzed.Using the methods of spatial-temporal evolution analysis, long time series analysis and orbit comparison of multi-parameter, the related abnormal phenomena in ionosphere are studied before earthquakes in WenChuan, Chile and Haiti. The law is summarized, such as: The anomalies are appeared frequently in 1~3 days and 8~10 days before earthquakes; The anomalies are appeared frequently in parameter of NO+,Ne and Ti; The time and location which NO+ and Ti appear are bound up with each other; and the plasma parameters have strong locality. All the research above accumulate experience and lessons for observing abnormal phenomena in ionosphere before earthquakes and lay the preliminary foundation for the application of the CSES data in future.The research findings and conclusions in this paper have been adopted in the development of ground application system of CSES, and have practical significance. |
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