A Distributed Coaxial Cable Strainmeter for Earth Monitoring

1442623 weii该资助支持分布式同轴电缆应变仪的开发和测试，该应变仪具有高精度（~ ppm）和高时间分辨率（~1秒）测量的潜力，具有前所未有的高空间（~ 10米）分辨率超过公里。该概念将依赖于同轴电缆的周期性电磁阻抗不连续（布拉格光栅）测试，该测试允许脉冲输入的电磁波通过同轴波导或同轴电缆内植入的反射器进行弱反射，从而实现基于Fabry-Perot干涉测量的同轴应变仪。然后使用矢量网络分析仪分析透射和反射光谱。PI还将探索新的信号放大技术，以减少沿电缆长度的多个传感器点返回的EM脉冲的损耗。基于同轴电缆的应变仪在大变形（5%）和强烈的横向碰撞/冲击中幸存的潜力，可能在某些基于光纤的应变技术可能失败的极端条件下（例如，滑坡，冰下变形，钢结构变形）提供有价值的和其他不可访问的信息。该开发将聘请一名研究生协助：1)开发用于设备设计和优化的新建模方法，2)探索混合软件-硬件信号处理技术；3)制作便携式同轴应变仪原型；4)描述原型？S在实验室和现场的性能

1442623WeiThis grant supports development and testing of a distributed coaxial cable strainmeter that has the potential to offer high accuracy (~ ppm) and high temporal resolution (~1 sec) measurements with unprecedented high spatial (~ 10 m) resolution over kilometers. The concept will rely on tests of coaxial cables that have been imparted with periodic electromagnetic impedance discontinuities (a Bragg grating) which allow for weak reflections of a pulsed input of an electromagnetic wave through the coaxial waveguide or implanted reflectors within the coaxial cable that will enable a coaxial strainmeter based on Fabry-Perot interferometry. A vector network analyzer then is then used to analyze transmission and reflection spectra. The PI would also explore novel signal amplification techniques to reduce losses from returned EM pulses along longer lengths of cable with multiple sensors points along the length of the cable. The potential of the coaxial cable based strainmeter to survive large deformations (5%) and strong lateral collision/impact, may provide valuable and otherwise inaccessible information under certain extreme conditions where fiber optic based strain technologies may fail (e.g., landslides, subglacial deformation, steel structure deformation). The development will engage a graduate student to assist with: 1) development of new modelling methodology for device design and optimization, 2) explore hybrid software-hardware signal processing technology; and 3) build a portable prototype coaxial strainmeter; and 4) characterize the prototype?s performance in the laboratory and in the field.***