测试土壤含水率和电导率的时域反射仪系

研究了用于土壤参数测试的时域反射仪(TDR)系统原理与电路实现方法.根据系统设计要求设计出时域反射仪样机,该样机脉冲发生电路产生140 ps上升沿的时域脉冲,接收电路等效采样精度为8.69 ps,并设计了时域反射仪系统控制程序,给出了程序的系统控制和数据处理流程图.利用研制的TDR样机对两种土壤样本的相对介电常数进行了测试,反演了土壤样品的体积含水率,同时利用采集波形反演计算出不同湿度土壤样品的体积含水率和体积电导率,反演体积含水率与称量法测的结果接近,测试误差均小于4%.

of Time Domain Reflectometry for Application of Soil Moisture and Bulk Electrical Conductivity Measurements

A time domain reflectometry(TDR) used in soil measurements was developed.Based on the measurement requirements of soil parameters,the TDR prototype was designed and manufactured.The pulse generator of TDR can produce a pulse with 140 ps rising-edge.The equivalent sampling precision of the TDR receiver was 8.69 ps.TDR control software was also programmed and the flow chart of the program was illustrated.The relative permittivities of sand and soil were measured.The volumetric moisture content and electrical ...