Design of wireless sensor network node for data transmission in tea plantations

A wireless sensor network (WSN) node was developed for information collection in a tea plantation, aimed at boosting wireless penetrating power through communication barriers. The node uses the ATmega128 as the core, a nRF905 RF chip and its periphery circuits as the wireless communication module, SHT11 temperature and humidity sensors and TDR-3 soil moisture sensor as its sensor module. Communication protocol, application program and background management software were compiled and embedded into the node. Communication distance and energy consumption of the node were tested and analyzed. The effective communication distance was measured up to 150m in broad smooth areas. By comparison with Micaz node of Crossbow, the indoor and outdoor distances of the node increase by 200% and 150% respectively. A WSN of 7 nodes was established for measuring temperature, humidity and soil water content in a tea plantation. Experimental results show that the average packet loss rate is 0.84% and the measurement precision is not less than 98.2%. The node is suitable for and could meet the needs of data acquisition in a tea plantation.