Research On Electromagnetic Interference Pre-test Technology Of Spectrum Monitoring Equipment

With the continuous expansion of the application fields of electronic and electrical products,the explosive growth of various types of products,the number and business of the products have brought about great convenience to people's lives,and it has also made the daily electromagnetic environment more and more complicated.In order to regulate and reduce the electromagnetic radiation effects that may be caused by electronic and electrical products,all countries require that products must pass relevant certification tests before they are listed.In order to ensure that the test is effective,economical,and practical,the study of electromagnetic compatibility test methods for the device under test is therefore very important and necessary.A certain type of spectrum monitoring equipment was discovered during the application process and the situation of external radiation emission of the whole machine was serious.In order to locate the radiation emission anomaly of this type of mass production equipment and reduce the cost of expensive third-party testing,the thesis conducts electromagnetic interference(EMI)pre-test method and its implementation technology for this equipment,and further through data processi ng and analysis.,gives possible radiation abnormalities.The main content of the thesis is as follows:First,the composition and working principle of the spectrum monitoring equipment to be tested are introduced.The structure,working mechanism,and pr inted circuit board(PCB)layout of the main circuit modules such as RF receiver circuits,digital signal IF processing,and frequency synthesizers of the Equipment Under Test(EUT)are studied.The transmission mode of electromagnetic interference in electrical equipment and the causes of electromagnetic interference inside and outside the equipment.It focuses on the analysis of passive signal intermodulation of EUT modules by listing the higher harmonics and the second-and third-order intermodulation products of EUT operating frequencies.The source of electromagnetic interference within the EUT is given.Second,the thesis studies several typical electromagnetic interference pre-test schemes.By comparing the technical features and applicable occasions of each scheme,it is determined that the electromagnetic interference pre-test scheme based on the virtual darkroom technology is used to complete the EMI pretest of the EUT.This sets up the test system hardware platform and software framework.Next,the thesis introduces the field test data processing method and database construction of EMI pretesting system for certain spectrum monitoring equipment.Detailed description of the radiation emission anomaly data extraction process based on the measured background signal template library,including: wavelet denoising algorithm,peak extraction algorithm,envelope extraction algorithm,matching algorithm design,and the correlation between various databases,data tables Content and other details.Finally,the EMI pre-test implementation process of the equipment to be tested using the above EMI pre-test scheme and data processing method is introduced.Based on the analysis of on-site measured data,the possible causes of radiation anomalies were compared with the analysis of the passive intermodulation combination of the aforementioned EUT.Based on the comparison of EMI pre-test results before and after the anomalous circuit was applied with shielding,the validity of the thesis' s research was illustrated.