Wireless system for soil water content measurements by TDR
We present a wireless TDR system to measure the soil volumetric water content and bulk electrical conductivity from a smart phone. The system consists of an M5Stack processing unit connected to a TDR device (Campbell TDR100 or Tektronix 1502C) through an RS232-ttl adapter. Software written in micropython runs on the M5Stack unit and allows the user to access a web-based graphical user interface (GUI) from a smartphone via M5Stack’s WiFi. The GUI facilitates controlling the TDR device, record waveforms and perform measurements in real time. Since waveforms and measurements can be stored on the smartphone, a separate data-logger is not needed. In addition, a webpage compatible with recorded data is available for subsequent TDR waveform analysis (Villoro et al., 2020).