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Wireless Sensor Network to Monitor Spatio- Temporal Thermal Comfort of Polyhouse Environment

A.M. Pawar, S. N. Patil, A. S. Powar and B. P. Ladgaonkar

Precision agriculture is an innovative technology, wherein the crops are cultivated in controlled environment. Emphasizing the need of precision agriculture, an electronic system is designed to provide thermal comfort to the crops of polyhouse environment, wherein an ubiquitous technology, Wireless Sensor Network (WSN) is deployed. To realize the establishment of wireless sensor network, a wireless sensor node is designed using embedded philosophy and presented in this paper. Availing promising features of AVR ATmega 8L microcontroller, the wireless sensor node is designed to monitor the thermal status of the polyhouse environment in spatio-temporal domain. The precision temperature sensor LM35 is employed to read the thermal status. Moreover, the signal conditioning circuit is wired about TLC 271, which operates on one power supply only and exhibiting very high input impedance with rail to rail input. An analog signal is digitized with on chip analog to digital converter with 10 bit resolution. The controlling unit is also designed to activate the heater as well as ventilators. To ensure wireless communication, the Zigbee model from Digi corporation is deployed as RF module. The sensor nodes are calibrated to the real unit and its performance is confirmed by comparing the results with standard digital thermometer. Each sensor node is assigned with network ID and it communicates the data with the respective ID in star topology. The present wireless sensor network is deployed in the polyhouse to monitor thermal status. It works continuously and precisely to hold control on temperature of the domain with great reliability.