Performance evaluation of two types of heated cables for distributed temperature sensing-based measurement of soil moisture content

Distributed temperature sensing (DTS) using heated cables has been recently developed for distributed monitoring of in-situ soil moisture content. In this method, the thermal and electrical properties of heated cables have a significant influence on the measurement accuracy of soil moisture content. In this paper, the performances of two heated cables, i.e. the carbon-fiber heated cable (CFHC) and the metal-net heated cable (MNHC), are studied in the laboratory. Their structures, uniformity in the axial direction, measurement accuracy and suitability are evaluated. The test results indicate that the MNHC has a better uniformity in the axial direction than CFHC. Both CFHC and MNHC have high measurement accuracy. The CFHC is more suitable for short-distance measurement (≤500 m), while the MNHC can be used for long-distance measurement (>500 m).