A New Linear Non-Contact Position Sensor for Harsh Environments

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This paper is a description of the DIST (Distributed Impedance Sensor Technology) sensor, a new patented non-contact linear position sensor. We will only be discussing the linear applications of this technology; in future papers we will cover other uses such as rotary, gap sensing and liquid level. This sensor is economical and is also capable of operating in harsh environments such as at temperatures in excess of 225°C, high radiation, vibration and high-shock. It requires only one wire for both power and output signal and can transmit the signal over lengths in excess of 10 meters. It is an absolute linear encoder which can measure lengths from a few millimeters up to one meter while maintaining accuracies in the micron region. The output of the sensor is frequency, a digital signal, and is not sensitive to noise and attenuations in the signal path. The sensor requires only a standard frequency meter to interpret the position. It requires no magnets or magnetic material and is insensitive to external magnetic fields. The DIST sensor can be manufactured with redundancy in the same physical package with only a small increase in diameter (but not length) and can be made triple redundant allowing majority logic.