A New TDR Multiplexing System for Reliable Electrical Conductivity and Soil Water Content Measurements

摘要: Time domain reflectometry (TDR) is a standard method to estimate soil water content and bulk electrical conductivity. In many applications, several TDR probes are installed in columns or field setups, measurements acquired using multiplexing system. Commercially available multiplexers share common ground, which might lead inaccurate when close together at sites with high electromagnetic noise. Therefore, new eight-channel differential multiplexer (50C81-SDM) was developed that allows communication equipment. first step, the tested analyze channel noise variability for open reflection coefficients travel times. The results indicate there no significant difference between channels both coefficient Second, 50C81-SDM electrolyte solutions sand tank. contrast they showed interference of closely spaced (spacing ranging from 5 95 cm). On other hand, SDMX50 absolute differences conductivities >0.001 Sm −1 volumetric contents conductivities. Measurements test site applicability such environments, but only if entire setup disconnected permanent power supply.