Ent N9912A (Agilent Technologies Inc., Santa Clara, CA, USA) handheld spectrum analyzer was employed to detect the signal intensity of WUSN nodes, plus a TJSD-750 soil compactness tester (Zhejiang Topu Yunnong Technologies Co., Ltd., Hangzhou, China) was utilised to detect soil compactness. A Tr-3001 soil multi-parameter tester (Jinan Renzhi Measurement and Handle Technology Co., Ltd., Jinan, China) was utilized to detect soil temperature, humidity, and acidity. two.two. WUSN Node Design and style and Soil Test Platform Construction Process The wireless underground sensor network node consists of a VSM-3000 soil moisture sensor (Shandong Weimengshi Technologies Co., Ltd., Qingzhou City, China), an STC89C52 single-chip microcomputer, and an HC-12 radio frequency 25-Hydroxycholesterol manufacturer module (Guangzhou Huicheng Facts Technology Co., Ltd., Guangzhou, China) that utilizes typical one-quarter wavelength unipole omnidirectional antenna and GFSK modulation [35,36]. In the design and style in the energy supply module, an external battery pack was employed to supply power. The WUSN nodes need to be waterproof since the deep soil moisture is high. In the experiment, the WUSN nodes were packaged in waterproof plastic boxes, as shown in Figure 2.Figure 2. WUSN nodes (a) prior to node encapsulation, and (b) immediately after node encapsulation.The composition of soil directly impacts the signal transmission good quality of WUSN nodes [37,38], however it is difficult to proficiently test WUSN node communication on account of the complexity and diversity of farmland soil parameters and also the interference of a lot of external components. In this study, a soil test platform was built in the laboratory, and modulated soil was made use of to test WUSN node communication. The size in the soil test platform is two.5 1 1.5 m, and the platform is produced of copper and nickel metal electromagnetic shielding material. Therefore, the reflection generated by WUSN node signals inside the platform may be ignored. Because the shielding material just isn’t waterproof, a layer of waterproof plastic covered the outside from the shielding material. The image on the soil test platform is shown in Figure 3. The soil employed inside the experiment was taken from the underground of farmland in Yangling District using a depth of 30 cm to 70 cm. Following natural air drying, the soil was sieved by means of a sieve with an aperture of two mm. As outlined by particle size, the soil was divided into sand, silt, and clay particles [39]. The DFHBI Autophagy physical properties from the soil employed for testing are listed in Table 1.Remote Sens. 2021, 13,4 ofFigure three. The soil test platform: (a) outside the platform, (b) inside the platform, (c) sieve soil, (d) inside the platform right after waterproof remedy, and (e) buried location of WUSN nodes. Table 1. Basic physical properties of your soil for test. Particle-Sized Fractions ( ) Soil Sort silt loam Sand (two.02 mm) 37.six Silt (0.02.002 mm) 41.six Clay (0.002 mm) 20.When the WUSN node communication test was carried out around the soil test platform, the soil variables below test had been adjusted according to the test scheme listed in Table A1. Among them, the soil moisture content was changed by adding pure water towards the soil inside the platform and stirring evenly; the soil compactness was changed by pressing the soil surface inside the platform with heavy objects; the soil acidity and alkalinity have been changed by adding ferrous sulfate or industrial soda for the soil inside the platform and stirring evenly; the soil temperature was changed by adding low temperature- or higher temperature-treated soil to the.