A piecewise analysis model for electrical conductivity calculation from time domain reflectometry waveforms

Electrical conductivity (EC) represents a material’s ability to conduct electric current. Soil EC has been used as soil quality attribute related pH, nutrient availability, crop suitability and microbial activity. Time domain reflectometry (TDR) estimates water content based on the propagation/reflection energy attenuation of voltage signals along waveguide. To maximize data use efficiency, waveform interpretations for simultaneous determination are needed. A tangent line/bounded mean oscillation (TL-BMO) model is available estimate from TDR waveforms, but an associated not yet available. The objectives this study (1) introduce piecewise analysis method interpretation, (2) develop computation waveguide under homogeneous content. proposed sequentially fits coaxial cable, connection, according transmission line equation. can be discretized into multiple successive pieces variations Simplifications fitting procedures via existing models, e.g., TL-BMO Topp et al. (1988) waveforms obtained controlled conditions, in distilled room temperature (~20 °C) air pressure (~101 kPa), also applied. Accuracy stability tested observed uniform conditions perturbated with range noise levels. values computed only one piece (i.e., no discretization waveguide) consistent theoretical values, results robust all As number levels increase, numerical oscillations increase. maximum relative errors <20%, occurring when power large (0 dB noise). Flexibility using simulated spatially varying EC, detected by model. In summary, provides reliable estimations, it evaluate or distributions moisture conditions. This imbedded integrated commonly measured (251-scanning point) waveforms.