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首页> 外文会议>Conference on Earth Observing Systems VII, Jul 7-10, 2002, Seattle, USA >Remote sensing of liquid characteristics using Time Domain Reflectometry
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Remote sensing of liquid characteristics using Time Domain Reflectometry

机译：使用时域反射仪遥感液体特性

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摘要

Time domain reflectometry (TDR) instrumentation is widely used in hydrology and soil science for accurate and flexible soil water content measurements. The most attractive advantages concerning the considered TDR measurement system are: good precision and accuracy, high reliability of the measuring head, an unique approach of pulsing a long coaxial probe and analysing the reflected voltage signature caused by changes in impedance, capability of multiplexing several probes, possibility of remotely acceding, controlling and electronically retrieving and transmitting data through existing telecommunications. A time domain reflectometer transmits the incident signal, an ultra short rise time (200 ps), step voltage pulse, along the transmission line and records the travel time and magnitude of all reflected signals (echo) returning from the controlled system. Changes in capacitance, impedance, inductance and resistance causing electromagnetic discontinuities that reflect voltage can be located, particularly, for liquid level and soil dielectric properties monitoring purposes, discontinuities result from impedance changes produced by changes in the dielectric constant. Moreover, different systems are currently used to measure liquid levels in stocking tanks or vessels. The time domain reflectometry method used in this research has the purpose to monitor the behavior of the different liquid interfaces, detecting their levels. One of the the goals of present paper is to enhance field measurement capabilities; miniature pulsing and sampling cards have been used to create a smaller and more rugged time domain reflectometer, associated to the special steel probes working like a closed circuit radar, detecting any mismatch along the measuring lines. Measurements can be performed in a wide range of environmental conditions, independently from the nature or properties of the involved substances, giving information about their characteristics, such as volumetric content, dielectric constant, emulsions, dispersions, etc.. Agreements with current TDR research data have been found. Furthermore, by characterizing several complex systems, the main objective of the present work is to develop an interpretation method based on the changes in the reflected TDR signal caused by the presence of hydrocarbons and their concentration in a soil.
机译：时域反射仪（TDR）仪器广泛用于水文学和土壤科学中，以进行准确而灵活的土壤含水量测量。所考虑的TDR测量系统最吸引人的优点是：精度高，精度高，测量头的可靠性高，对长同轴探针施加脉冲并分析由阻抗变化引起的反射电压信号的独特方法，多路复用多个探针的能力，可以通过现有电信远程访问，控制以及以电子方式检索和传输数据。时域反射计沿着传输线传输入射信号，超短上升时间（200 ps），阶跃电压脉冲，并记录传播时间和从受控系统返回的所有反射信号（回波）的幅度。可以找到引起反射电压的电磁不连续性的电容，阻抗，电感和电阻的变化，特别是对于液位和土壤介电特性监测而言，不连续性是由介电常数变化产生的阻抗变化引起的。此外，当前使用不同的系统来测量储存罐或容器中的液位。本研究中使用的时域反射仪方法旨在监视不同液体界面的行为，检测其液位。本文的目标之一是增强现场测量能力。微型脉冲和采样卡已用于创建更小巧，更坚固耐用的时域反射仪，与像闭路雷达一样工作的特殊钢探针相关联，可检测沿测量线的不匹配情况。可以在广泛的环境条件下进行测量，而与所涉及物质的性质或性质无关，可以给出有关其特性的信息，例如体积含量，介电常数，乳液，分散液等。与当前TDR研究数据的一致性被发现。此外，通过表征几个复杂的系统，本工作的主要目的是开发一种基于碳氢化合物的存在及其在土壤中的浓度引起的反射TDR信号变化的解释方法。

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