Investigation On Key Techniques Of Electromagnetic Compatibility Maintenance For Electronic Information Systems

State of Electromagnetic Compatibility(EMC) of electronics equipments and systems is achieved via scientific and appropriate EMC design and fabrication, and is kept by timely and effective EMC maintenance. In recent years, as the quickly increasing of military outfits using frequencies and civil radio equipments, the electromagnetic environment takes on the situation of more and more complex, and incompatibility problems including electromagnetic self interference as well as mutual interference increase as time goes on. On the other hand, diagnosing of the electromagnetic interference is difficult and tools for on-site EMC testing and analyzing are not adequate, when the compositive application on measured data is deficient. Consequently, the thesis studies techniques and methods of EMC maintenance and seeks after scheme of design and realization for the system, which aims to keeping or renovating EMC state of electronics and informatics systems.The work carried out and completed during the research of this thesis can be divided into theoretics, methods and techniques, which is expatiated as follows.I. Concepts and theoretics of EMC maintenanceBasic problems in the field of EMC maintenance are studied firstly according to the focus task of maintenance. Concepts of EMC maintenance, EMC predictive maintenance, EMC reliability, EMC model synthesis, EMC physical check-up and EMC replenishment are put forward. Definitions of them are presented or clarified and the meanings are explained. The academic and technical framework of EMC maintenance for outfits has been built and some theoretic problems in the area of EMC maintenance have been solved.The thesis discusses main ideas of maintenance, replenishment and health management based on the above. Diagnosing methods for EMC failures together with analysis of the reasons are analyzed. Methods of data preprocessing for EMC model synthesis are provided. Description parameters of EMC reliability are defined and the EMC life-span of outfits is analyzed. Evaluation methods of effect of EMC maintenance are brought forward. Operating contents of EMC enhancement and revision as well as the intention, principle and implementation methods are described.II.EMC prediction methods based on measured dataHow to carry out thorough analysis and data mining on EMC measurement data and results of the analyzing and how to predict EMC performance of the system based on it are studied in the thesis. Statistical annlysis methods of EMC prediction for informatics systems are put forward. Practical designs are discussed according to engineering complexions, includes rules and methods of segment division as well as application of curvature, tangent and grads. Algorithm of Artificial Neural Network(ANN) and its application in EMC is studied. Features and selection of the training algorithms together II. EMC prediction methods based on measured data with the determination of the learning rate are analyzed. The method of EMC model synthesis based on ANN is brought forward. Algorithms of Artificial Bee Colony(ABC) and Artificial Fish Swarm(AFS) are studied, which are Swarm Intellgence(SI) bionics algorithms. Ideas and means of fuzzy mathematics are studied and EMC model synthesis based on fuzzy techniques is discussed. An EMC prediction method combining fuzzy and ANN is put forward. The algorithm of AFS optimized by Particle Swarm(PS) is analyzed. Algorithms studied in the thesis are elucidated or validated with electromagnetic sensitivity or radiation and conductive characteristics of radars or communications equipments separately.III. Research on key techniques of the EMC maintenance system and its developmentEMC testing and analysis are important techniques in the area of EMC maintenance. Testing methods, environments and systems of EMC are analyzed. Difficulties of on-site testing are studied and the comparison with the standard testing is presented. The signal processing methods of on-site testing are discussed. General methods for EMC analysis and forecasting are described. The analysis method based on electromagnetic topology for propagation of interference signals is studied with emphasis.The requirement of the EMC maintenance system is analyzed first. Then the functions and constitution of the system that we developed are explained. The idea for the design is provided and the important and the difficult points when developing subsystems of measurement, simulation, model synthesis and database as well as the mobile platform are expatiated, especially the optimization and revision measures to improve the testing and analyzing abilities of the system. The integration of the subsystems is studied too. The design method and the realization techniques of the subsystem of model synthesis are focused. The statistical and intellgence algorithms are used in it. Receiving techniques for electromagnetic signals are investigated, especially the wideband compensating technique. Design methods of the wideband switch, filter, local oscillator with low phase noise and the moudule of microwave frequency converter are presented. The description of testing and analysis and experiment results of some typical outfits and platforms for their electromagnetic environment, emission and sensitivity characteristics are displayed.The achievements of this thesis will benefit special measurement, active management and predictive maintenance and replenishment in the area of EMC. And they can support the change form passive EMC maintenance to active. Methods and models put forward in the thesis have been used in the EMC maintenance system and experiments on informatics systems of key platforms including ships, submarines and airplanes have been carried out with fairly good effects.