An embedded wireless sensor network at 433MHz for agricultural applications

The use of environmental sensors in agriculture and precision agriculture applications is becoming more common, although implementation strategies and capital costs prohibit widespread adoption by many in the industry. Typical costs for agricultural monitoring systems can be in the tens of thousands of dollars per site. This paper presents low cost, wireless sensor nodes and a corresponding low power network. The nodes use biodegradable plastic to house die sensor, support electronics, RF transceiver and a 433 NMz antenna. In this paper the antenna design and network topology is discussed together with the propagation problems associated with a field environment in which the vegetation changes weekly. It is envisaged that such a platform could be ploughed in to the field at the end of its working life. The total cost of construction of the prototype platform is approximately $US 10 per sensor. A communication protocol was also developed to allow many of these devices to be installed simultaneously and for the transmission of collected data and dynamic configuration and reprogramming. A receiver system allows for the collation and presentation of collected data. Low cost soil moisture sensors were coupled to the platform and installed in a commercial nursery wholesaler. Field trials of the network were successfully conducted.