Development Of Cable Fault-Locating Module

Fault location for plane cable is an important element of plane maintenance. The types of plane cables are complex, there are all kinds of radio frequency cable, data cable, low voltage power calbe. Plane cables are all over the plane like human's arteries, and they are often tied by category are placed into a folder in the plane wall. Therefore, it's difficult to locate the fault cable by human. At present, the maintenance equipments are mainly by time-domain reflectors which imported from abroad, but this kind of equipment has great limitations. Only a few large national maintenance bases have such measuring equipments and the rest of the maintenance bases locate the fault calbe by human. Therefore the development of cable fault location unit has important application values.Combined with actual conditions of plane cable, this paper compared a variety of cable fault location methods and finally adopted the low-pressure pulse reflection method. With the studying on the avalanche transistors in the avalanche work area and improving the Marx circuit, this paper designed and developed a pulse transmitter which can launch high amplitude narrow pulses. This paper also designed a signal modulate circuit which can meet the data collection requirements. Meanwhile, a data acquisition system with 5GHz equivalent sampling rate and a eCan communication interface which can implement CAN bus communication have been designed. By using DSP TMS320F2812 as the master controler, it can pre-process the sampling data and calculate the cable fault location.In the aspect of the softwares, this paper designed the algorithm which can calculate the time difference accurately through studying literatures of measuring the time difference and the pulse waveform. Visual C++ is used to develope a good PC program interface, and ADO technology is used to design the database to store the velocity and the historical data.In the laboratory condition, the test results show that the low-pressure pulse reflection method can locate cable fault accurately.