Vehicle Mounted Soil Conductivity Detection System Based on Digital Oscilloscope

Generally, there are two methods to detect soil electrical conductivity, which are contact and non-contact. Among them, the development of contact soil conductivity meter is generally based on the principle of current-voltage four-terminal method, using constant current source as excitation source and voltmeter as feedback signal detection equipment. Based on the principle of current voltage four terminal method, the signal generator instead of constant current source was used as excitation source to provide sine signal with larger amplitude and higher stability, and the digital oscilloscope was used to replace voltage source for feedback signal detection, so as to solve the problem of slow frequency of voltage RMS conversion and AD conversion. A soil conductivity detection system based on digital oscilloscope was developed. The field vehicular measurement experiment was divided into two parts: stability detection and fixed-point measurement. Under the stability test, the detection system can read the relevant data stably. Field fixed-point measurement experiment combined with soil sample collection and laboratory experiment, the measured value of soil conductivity and the true value of soil conductivity at each fixed point were obtained. Based on the field experiment data as the ordinate and the laboratory measurement as the abscissa, the data scatter diagram was drawn, and R2 was 0.753 1. In order to further explore the problem of poor correlation of experimental data, according to the situation of two kinds of measurement contact surface between electrode and soil to be measured caused by tractor traction plow disc shaking in the experiment. After analyzing and eliminating the influence of tractor shaking phenomenon on the data results, the determination coefficient R2 between the measured soil conductivity data and the experimental data can be increased to 0.855 2~0.906 6, which indicated that the equipment can achieve a high level of measurement accuracy without the influence of external factors such as measurement methods. According to the comparison of experimental data, the results showed that the vehicle mounted soil conductivity meter based on digital oscilloscope can stably measure in farmland, and had good performance and accuracy. © 2020, Chinese Society of Agricultural Machinery. All right reserved.