Home // International Journal On Advances in Systems and Measurements, volume 11, numbers 3 and 4, 2018 // View article
Authors:
Antonio Valente
Arata Saraiva
Nuno M. Fonseca Ferreira
Salviano Soares
Keywords: soil moisture sensor; soil thermal properties; dual-probe; heat-pulse sensor; thermal conductivity; thermal sensors.
Abstract:
There is a need for a multi-functional probe for small-scale measurements of different soil properties measured within identical soil volumes. Dual Probe Heat Pulse (DPHP) sensors are an economical solution for this since they measure simultaneously temperature, volumetric water content, and soil thermal properties: diffusivity and volumetric heat capacity. However, all DPHP sensors to date have very complex manufacturing processes. This paper aims to design and build a DPHP sensor based only on a Printed Circuit Board (PCB) board, which comprises the probes and all supporting electronics leading to a low cost and simple manufacturing process. The proposed system includes signal-processing circuits, a microcontroller, and communicates by a Serial Digital Interface at 1200 baud protocol (SDI-12). The sensor needs a one-time two calibrations: distance from heater to temperature sensor calibration using agar solution; and sensor calibration in soil using Tottori Dune sand. Both calibration processes showed a reasonably good agreement between measured and fitted data. In conclusion, results also show that it is possible to build the multi-functional DPHP sensor in a low cost process, and this was the first time that a multi-functional probe was build using a Printed Circuit Board (PCB) as support.
Pages: 259 to 268
Copyright: Copyright (c) to authors, 2018. Used with permission.
Publication date: December 30, 2018
Published in: journal
ISSN: 1942-261x