Soil Moisture Remote Monitoring System Research And Design

Soil moisture is an important part of the soil, which is the main supply source for the crop growth. It is also concerned with the important soil physical, chemical and biological processes. Therefore, collecting and monitoring the soil moisture content timely and accurately is vital for the growth of crops. The existing soil moisture measurement techniques have different features, but most of them only can achieve the designated time and data acquisition, and can not be combined with the remote control center, which therefore can not analyze and control the detected data in real-time. Based on the above background, and in order to achieve the purpose of measuring and monitoring the soil moisture content fast and accurately, the data collection and remote monitoring system based on TDR technology and GSM technology is designed and studied in this paper.With the use of Time Domain Reflectometry to collect the soil moisture content in real-time, it can get the fast, accurate and continuous measurement, which can get the range from 0 to 100%. Moreover, this method does not destroy the soil itself, and it can digitally display the soil moisture content. According to the principles of TDR technology, the TDR probe, TDR 100 time domain reflectometry, data collection device, coaxial cable and other equipments are used in the acquisition part of the experiment. The TDR probes are put into the soil samples, and then opening the TDR100 time domain reflectometry, which issue the waveform signal and collect the feedback signal. With the dielectric constant calculated by the TDR method, the soil moisture content data can be obtained. After the measurement, we carried the compared and calibration experiments with the drying weight method, and discussed the accuracy of TDR method. At the end of the experiment, in order to reduce the cost, the use of copper probe was explored to instead of the traditional TDR stainless steel probe. the results comparison and linear regression analysis were also made in the paper.In the transmission part of the system, the interface circuit is added with a GSM communication module, which can achieve the automatic monitoring, remote controlling, transmission and other intelligent operation based on its remote wireless transmission characteristics. With the short message service of the GSM module, the information data not only can be sent to monitoring center and stored or made analysis with the Delphi software platform and setting database, but also can be sent to user terminals to make them keep abreast of the soil moisture information. The user terminals and monitoring center can make the real-time information transmission to each other with the short message service.In order to facilitate the debugging and modification, module pattern design is used in the system. Hardware and software design are the two parts of the design project. The hardware system consists of several modules, including data collection circuit module, GSM interface circuit module, microcontroller and related peripheral circuits. The paper compares and analyses the advantages and disadvantages of used devices and other devices, and introduces the choice and connection of each module in detail. In software design, we use Delphi as the computer control system software. The system design not only can make the received data for storage, query and other functions, but also can monitor and delivery the change of the parameters. The lower computer software design includes the collection of soil moisture information and the wireless reception and transmission. The design can be divided into system initialization, real-time acquisition and processing of soil moisture parameters, wireless communications between MCU and GSM module, short message processing procedures, etc..The tests are conducted after the completion of the hardware and software design, and the final experimental results are analyzed. For the drying method, the TDR method regression curve is y=10.037x-15.191, and the correlation coefficient is R2=0.9838. Adjusted by the formula,98.38 percent of the data in TDR measurement can be close to the real soil moisture content, which has the possibility in the experiment. With the timely and accurate remote transmission, the system has a certain significance and application value.