Studies On Key Techniques Of In-situ Test For System Level Electromagnetic Compatibility

Electromagnetic Compatibility is a functional ability, with which Electronic Equipment and System can use Electromagnetic Spectrum under the same electromagnetic environment to avoid the unacceptable degradation caused by electromagnetic radiation and sensitivity, implementing its function in turn. Consequently, it is crucial for any electronic device and system to be equipped with good electromagnetism compatibility.On the one hand, the modern information system is increasingly complicated as we are involved into the fast development of science and technology. Meanwhile, the number of electronic equipments loaded on the same platform is soaring, which also raised the requirement on electromagnetism compatibility. On the other hand, with electromagnetic environment becoming worse, electric products is confronted with increased Electromagnetic Interference, which leads to the significant increase of risk of performance degradation or defuctionalization of the product itself.With large-scale military weaponry in service time increases, and the impact of retrofit equipments, systems suffer from electromagneticmutual interference problems are becoming increasingly prominent. For warships, aircraft, satellites and other large platforms, measurement and analysis of electromagnetic compatibility can only be carried out in-situ. The reasons are as follows: Firstly, we have no standard test site can accommodate so large test objects and it is impossible to transport these large systems to standards open test site for testing; Secondly, the overall electromagnetic compatibility testing and analysis for large-scale platform needs the high-power transmitters to work at full capacity, wihich is clearly inappropriate; for indoor test; Thirdly, when there is electromagnetic compatibility problems arise, in order to ensure timely completion of technical and tactical tasks, the in-situ measuring means for investigation and analysis are needed. Finally, the in-situ environment closer to the actual working environment of the test object, the test results can reflect the actual situation well. At present, the researches and facilities development for electromagnetic compatibility standards testing have been more perfect in domestic. But for in-situ testing research is still in its infancy, few academic monographs and papers, relevant standards and the corresponding test technique lacks, so carry the study of electromagnetic compatibility in-situ test is important and urgent.This paper focuses on the key technology of in-situ EMC on system level, making breakthroughs in a wide range of technologies including rapid measurement for electromagnetic emission, environmental interference suppression, equivalent sensitivity analysis, nonlinear sensitivity analysis and modeling for receiver, and non-standard test data analysis,which provides an important technical means. for military equipment in electromagnetic compatibility in-situ test.The first part is presented with the research status of in-site EMC on system level at home and abroad, the research background, the main research content and framework of the paper.The second part introduces the research on the method of Environmental interference suppression, focuses on a new method of Environmental interference suppression based on spatial filter. The complete theoretical derivation is given in this part, along with the detailed calculation about the influence brought by the relevant factors to testing performance. This method is tested effectiveness by means of In-sute test.The third part carries out the measurement method of Electromagnetic Susceptibility tests for receiver system. The dual-frequency test method for sensitivity test of receiver has been improved. The channel frequency constraints of the super heterodyne receiver are used to calculate all combinations of frequencies which fall into IF band of the receiver. The narrowband measurement is carried out according to the IF output frequency based on the calculated, and the measurement time is reduced greatly. Based on dual-frequency tests, the modeling method of sensitivity for the receiver is proposed. The method fits a mathematical of receiver’s input and outpu based on limited test datat. Whether the signals will be able to interference the receiver can according to the theoretical criteria of this model. the introduction of the antenna pattern characterization simplified method and terminal response level division, so that the test method is suitable for large-scale systems and modeling of field measurements, has a high value in engineering. The method to simplify for antenna pattern and classificate the terminal characterization of the response is suitable for in-situ test for large-scale systems.The forth part studied the extraction and analysis methods for non-standard in-situ test data. The paper proposed a non-standard data processing method of on-site measurements. The concept of the integral interference margin and a quick calculation way for broadband interference margin based on the number of frequency extracted is proposed. Under the premise of ensuring, the accuracy greatly reduces the amount of computation and enhances the speed of data analysis.Finally, the application of the results of this study is introduced. National University of Defense Technology, with leading domestic level, developed a system-level EMC in-situ test system. The overall design, system architecture, sub-systems and functions are elaborated. The general methods and procedures of the test system in the in-situ test are researched. The representative implementation process of system electromagnetic interference test and analysis effectively illustrate the important value of this study.