9 May 2005 Noise reduction in RF cavity wireless strain sensors
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Abstract
In this paper we will be describing noise reduction techniques for new type of wireless sensor for use in monitoring strain in civil structures. This strain sensor is a passive sensor that can be embedded and then interrogated through an attached antenna and hence has the advantage that is requires no permanent electrical or optical connection. The sensor is a metal coaxial cylindrical cavity embedded or attached to the object in which strain is to be measured. As the structure changes dimension in response to applied forces the electromagnetic cavity also changes dimension and hence its resonant frequency also changes. The sensor can then be interrogated via the antenna and the resonant frequency of the electromagnetic cavity determined. Once the resonance frequency is determined it can be used to calculate the strain in the structure. We will present results on the use of time domain gating to reduce environmental and instrumental noise. We will also present results using peak fitting techniques that make optimum use of signals to locate the resonance. These noise reduction techniques make the use of this type of sensor applicable in a wider range of environments. We have demonstrated a strain resolution of 8 microstrain in a noisy environment by using peak fitting techniques. These techniques were much less sensitive to environmental sources of noise than FM modulation and phase sensitive detection.
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Jenny Chuang, Jenny Chuang, D. J. Thomson, D. J. Thomson, } "Noise reduction in RF cavity wireless strain sensors", Proc. SPIE 5768, Health Monitoring and Smart Nondestructive Evaluation of Structural and Biological Systems IV, (9 May 2005); doi: 10.1117/12.600041; https://doi.org/10.1117/12.600041
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