Research Of Aircraft Cable Shield Grounding Reliability Testing Method

Today several electromagnetic interference and lightning threats exist for aerospace electronics. Electrical wiring shielding is used to reduce EMI/HIRF and lightning effects and to ensure that they do not cause hard failures in the electronics of the system and eventual system failure. In general the effectiveness of the shield in protecting the core wires is a function of the loop resistance; the lower the resistance,the better the shielding. Aerospace environments are detrimental to materials and bonds of the shielding. High levels of moisture, salt, and extreme temperatures are among conditions that create corrosion problems. If certainty of the shielding effectiveness is needed, it must be tested.First, an overview of the aircraft cable shield loop impedance test system is given in this paper, which introduces its hardware structure and auxiliary circuit. In order to ensure the reliability of power supply, a design of two power supply circuits are introduced, the amplification of the current not only can reduce the use of collection equipment so as to reduce costs but also can improve the signal to noise ratio, which makes it possible to analyze the subsequent signals.During the impedance measurement process, the signals collected need to be de-noised in order to obtain the accurate voltage and current signals. A method based on wavelet noise reduction and noise reduction method based on EMD together with their advantages and disadvantages are introduced in this paper, and a joint noise reduction method based on wavelet and EMD method is presented.Finally, the software design of the test system is described in this paper.Experimental results show that the test system has a good measurement performance,and the system can meet the basic needs of the design requirements.