Analysis And Test Of The Influence Of Aircraft Cable Termination On Transmission Signals

At present,civil passenger aircraft are developing in the direction of more electric aircraft and even all electric aircraft,then the types and quantities of aircrafts' cables have increased dramatically.When the cable is in an external high-intensity radiation field or in a complex electromagnetic environment generated by airborne equipment,Electromagnetic interference may occur on the cable due to electromagnetic coupling,which affects the quality of the transmission signals of the aircraft and even threatens flight safety.The use of twisted pair or shielded wire can effectively suppress electromagnetic interference,but when the cable termination method is not properly selected,the cable's ability to suppress external electromagnetic interference becomes worse.Therefore,it is of practical significance and application value to study the termination method of twisted pair core and cable shielding layer.In this paper,a cross-talk prediction model is established based on the theory of multi-conductor transmission line.The cross-talk prediction model is verified by numerical simulation of CST software.By the prediction model,the influence of different termination methods of the twisted pair on the transmission signal quality is simulated and analyzed.And for the balanced grounding of the twisted pair,the influence of the transmission signal is analyzed when there is an offset of the grounding resistance;Secondly,based on the equivalent structure of the inner and outer loops of the shield layer,a mathematical model for the influence of cable shielding effectiveness is established.After verifying the validity of the mathematical model,research on the ability of the cable shielding layer to terminate the interference signal by different termination methods,and the grounding impedance in the double-ended grounding of the shielding layer is studied.Finally,in order to further verify the influence of different termination methods of twisted pair and cable shielding on the transmission signal quality,an aircraft cable experimental verification platform is built and relevant experiments are carried out.According to the experimental results,the effects of different termination methods of the twisted pair core and the cable shielding layer on the transmission signal quality are further analyzed.Theoretical analysis and experimental verification can be obtained that the signal transmission quality on the aircraft is affected by the termination of the twisted pair core and the shield.The balanced termination of the twisted pair better than the unbalanced termination in suppressing the crosstalk signal;when the cable is balanced grounding,the ground-resistance offset reduces the quality of the transmitted signal.The double-ended grounding of the shielded cable can better ensure the quality of the transmitted signal,and when the shielding layer and the reference ground have a grounding impedance,the interference suppression capability is reduced.