Design and implementation of a soil moisture wireless sensor network

This paper presents the design of a shortest path tree based data collection wireless sensor network to sense soil moisture, soil temperature and relative humidity. Each node in the network follows a synchronized, periodic sleep - wake up schedule in order to maximize the lifetime of the network. The paper also demonstrates the implementation of a cluster based sensor network consisting of 10 nodes grouped as 3 clusters which collects and sends sensed data to a base station (here laptop) through a sink node. Data processing and presentation on the laptop is achieved using custom designed graphical user interface (GUI) in MATLAB. Nodes are kept approximately 8m apart covering an area of 400 m². The implemented sensor network features using in house developed, low cost dual probe heat pulse (DPHP) soil moisture sensor, soil temperature sensor and energy efficient wireless transmission using clustering architecture for agricultural application. Field testing for 20% moisture level is demonstrated while feasibility of measuring the moisture levels from 0% to 40% is established from lab experiments.