Research Of Aircraft Cable Fault Detection Based On Spread Spectrum Time Domain Reflectometry

Aircraft cable, providing power and control signals for electrical system, is widely distributed in the aircraft, which is playing a more and more important role in flight safety.With the long-term flight, the aircraft may suffer the problems of cable aging. While the plane is in flight, the cable failure is likely to result in catastrophic destruction to the aircraft. Inside of aircraft structure, the majority of aircraft cables are usually connected in a way of multiple joints. As the airplane cable fault detection based on TDR(time domain reflectometry) is affected easily by attenuation and various noise signals, which makes the reflected signal attenuate and distort heavily, failing to locate the fault accurately. Thus, the detection and localization of faults, with high immunity of noise and attenuation, is required strongly for diagnosis and maintenance of wiring systems.In order to solve these problems, a method of spread spectrum time domain reflectometry(SSTDR) is introduced in this paper, taking the advantage of the sharp peak of correlation function. The test signal is generated from pseudo-random sequence modulated by sine wave in the same frequency. Theoretically, the test signal has the very high immunity of noise and attenuation, which can be applied to fault location on the aircraft cable, with outstanding performance.In this paper, the method of SSTDR is normally simulated in MATLAB. Then, an experimental setup, based on LabVIEW, is organized to detect and locate the fault on the aircraft cable. It has been demonstrated that SSTDR has the very high immunity of noise and attenuation, reducing some detection errors for multiple joints effectively.