Evaluation Method And Its Application Of EMC For Vehicle-mounted Communication Equipment

Inside the communication vehicles,there are a large number of electrical devices and equipment that make the electromagnetic environment of the vehicle more complex and hash,which would lead to the devices’ performance degradation and breakdown when multiple devices work together.In the complex electromagnetic environment,the sensitive components of vehicle-mounted communication equipment are easily affected by interference signals,and results in serious electromagnetic compatibility problems.Once the communication devices are interfered and the performance are degraded,the communication system will suffer great losses.Electromagnetic compatibility of vehicle-mounted communication equipment is the key to the quality of communications.It is of great theoretical and engineering value to evaluate the EMC of communication equipment accurately.In this thesis,the electromagnetic compatibility evaluation of the vehicle-mounted communication equipment is studied.The indicators affecting EMC of vehiclemounted communication equipment are discussed and analyzed.Meanwhile,the electromagnetic compatibility evaluation system is established and a comprehensive evaluation method is proposed to evaluate the EMC of vehicle-mounted communication equipment comprehensively.The main works in this thesis as follow:1.The EMC evaluation system of vehicle communication equipment is established.By analyzing the characteristics of the vehicle communication equipment and the electromagnetic coupling relationships inside the vehicle,the EMC evaluation indexes are extracted.And the hierarchical structure is chose as the index architecture model.According to the construction process of the indicator system,the contents of the target layer,criterion layer and subcriterion layer are determined respectively.Then,a complete evaluation index system for EMC of vehicle communication equipment is established.2.A comprehensive method can be used to evaluate EMC of vehicle communication equipment is proposed.By analyzing the characteristics of the evaluation method of TOPSIS,AHP and the fuzzy comprehensive evaluation method,a fuzzy comprehensive evaluation method based on TOPSIS-AHP combination weighting is proposed.TOPSIS-AHP weighting method take the advantage of quantitative analysis of TOPSIS and qualitative analysis of AHP to determine the index weights of the sub-criterion layer and the criterion layer respectively.With the index weight determined,the two-level model of the fuzzy integrated evaluation method is used to evaluate EMC of vehicle communication equipment.Then the fuzzy evaluation set and the evaluation results are obtained.3.The changes of the receiver sensitivity with interference are analyzed.The relation between the propagation loss and the communication distance in free space and the ground environment are discussed respectively.In addition,by the propagation loss model in free space and the ground environment,the influence range of desensitization on the communication distance is calculated.Finally,based on the comprehensive evaluation method proposed in this thesis,the influence of sensitivity and communication distance on the final evaluation results is analyzed.