Study On The Prediction Of EMI Among Vehicular Wireless Devices

The space of vehicle platform was small, a number of and a variety of operating modes of radios in the same vehicle, it will bring serious problem of electromagnetic compatibility (EMC), which has affected the normal operation of communications systems, Therefore, the analysis and prediction of electromagnetic interference among the wireless equipments and putting forward the corresponding suppression is of great significance and value engineering.The prediction method of the co-site interference is respectively put forward for the three operating models: fixed-frequency, frequency-hopping (FH) and Direct Sequence Spread Spectrum (DS). In the fixed-frequency mode, using interference margin in model, and combined with existing laboratory simulation software, a co-site guard-band prediction model is established, and gave a briefing on how to use the method of test for transceiver's characteristic curve; in the frequency-hopping mode, for the random frequency hopping, through the introduction of instantaneous co-site guard-band, the prediction mode about frequency division network is established base on probability; in the Direct Sequence Spread Spectrum mode, through the analysis of interference tolerance, referencing the prediction method of co-site guard-band in the fixed-frequency mode, the prediction of equivalent guard-band base on frequency division Direct Sequence Spread Spectrum system is analyzed, Through the application in related projects, the accuracy of the above prediction models is validated.Based on the analysis of the desensitization of receivers caused by co-site interference, the impact between desensitization and communication distant is discussed in this paper. And the measures of reducing co-site interference are put forward, aim at characteristics of vehicular platform. So, it provides engineering guidance for the design of EMC in vehicular communication systems.