Bidirectional communication and control system of intelligent water-saving irrigation in litchi orchard based on wireless sensor network

In order to improve the utilization of water resources and satisfy the needs of intelligent irrigation management, an intelligent irrigation system combined with wireless sensor network technology as the core in litchi orchard was designed.The system used CC2530 as wireless communication module, combined with DHT22 air temperature and humidity sensors, GY-30 light intensity sensor, TDR-3 soil moisture sensor and peripheral circuit as a sensor module to collect a number of environmental information and data such as temperature humidity, light and soil moisture content.To achieve a real-time monitoring of litchi orchard environment, it ensured the transmission of real-time and remoted via wireless sensor networks, GPRS and the Internet transmission.In the mean time, litchi orchard soil moisture water content threshold had been set on remote servers and websites, when the value of the soil moisture content exceeds the threshold, the servers or websites would automatically send the relevant commands to control the corresponding solenoid valve to realize two-way control.The maximum bidirectional effective communication distance of the designed nodes reached 1 205 m in open field and 81.5m in litchi orchard.With a working cycle of 30 min, it could be estimated that two series lithium batteries with a rated capacity of 3 000 mA·h allows sensor nodes operating time up to 500 days and the solenoid valve control node can work more than 5 years.Experimental results showed that the system is stable with the average network packet loss rate of 3.87%, which can monitor the collection of information and control the solenoid valves accurately to achieve a bidirectional communication and control system of intelligent water-saving irrigation in litchi orchard.