I. Overview
The TDR-3A soil temperature and humidity sensor has the characteristics of high stability, easy installation, maintenance, and operation. In order to ensure strength and lifespan, ABS engineering plastic is selected as the supporting material. The TDR-3A soil temperature and humidity sensor has good sealing performance and can be buried in soil for a long time without corrosion. The output signal of the soil moisture sensor adopts standard current loop transmission technology, which makes it have strong anti-interference ability, long transmission distance, high measurement accuracy, and fast response speed.

2、 Basic principles
The TDR-3A soil temperature and humidity sensor uses a crystal oscillator to generate high-frequency signals, which are transmitted to parallel metal probes. The generated signals are superimposed with the returned signals, and the temperature and humidity of the soil are measured by measuring the amplitude of the signals. The characteristics of TDR-3A soil temperature and humidity sensor are high accuracy, wide range, multiple measurable material varieties, and fast response speed. It can be applied to online monitoring to achieve automation

3、 Typical applications
Soil temperature and humidity sensors are mainly used in agricultural irrigation systems, soil moisture monitoring, hydrological and water conservancy monitoring, etc. It can form a telemetry system with data acquisition and remote transmission equipment. For example, when the soil is dry, the telemetry system automatically alarms, while the control system automatically controls the opening and closing of water pumps and valves to achieve automation of irrigation. If combined with some additional sensors, the soil moisture evaporation and the required moisture parameters for crops can also be calculated.

4、 Technical parameters