Low power CMOS sensor for detecting faults in aircraft wiring

Wiring problems in aging aircraft have been identified as the cause of several tragic mishaps and hundreds of thousands of lost mission hours. Intermittent wiring faults, which occur during flight, have been and continue to be difficult to resolve. This makes it necessary to monitor live aircraft wires continuously, without affecting the aircraft signals on live wires.;The research in this dissertation was to develop a stand-alone sensor system in an application specific integrated circuit (ASIC), which can sense the nature of a fault in aircraft wiring both on the ground and in flight. The desired sensor is required to run on a small battery and not to rely on the aircraft power supply. This places a severe power constraint on the chip, pressing the need for low power operation for longer battery life. Size and weight constraints as well as the need for low power operation require an integrated circuit implementation of such a system.;The current methods to locate faults on live aircraft wiring in their present implementation cannot be fabricated in a commercial CMOS process due to the large value of the passive elements used in the current implementation. A novel method called the time domain vernier (TDV) method was developed, and a novel architecture was developed for implementing the TDV method into a CMOS integrated circuit sensor. This is the first known integrated circuit solution for locating faults on live aircraft wires.;The TDV sensor chip has an accuracy of +/- 1.5 ft and consumes 18.6 mW power. It can scan a cable of 100 ft length in 0.33 ms.;The TDV sensor is the first known low power sensor for monitoring live wires that can be installed in an aircraft in locations that are not accessible to the aircraft power supply. Circuit-level to system-level optimizations have been considered in this dissertation to improve the accuracy of fault location without increasing the power consumption of the sensor. This dissertation also looks at new algorithms and techniques, which can be added to the existing system to further improve accuracy. This dissertation provides a complete system on chip (SOC) solution to the fault location problem in live aircraft wiring.