To implement reliable wireless sensor networks suitable for use in “smart agriculture”, it is important to understand the radio propagation characteristics in the farm environment. In a farm field, crops and structures such as glasshouses or vinyl houses that lie between transmitter and receiver nodes affect radio wave propagation. Owing to multipath effects that arise from reflections of radio waves from crops, the ground, and other obstacles, slight differences among the node positions can affect the received signal strength indicator (RSSI). In addition, crops that are shaken by the wind introduce temporal variation into RSSI. In this paper, we measured RSSI based on radio propagation characteristics in the 920 MHz band, which is used in the Wi-SUN standard for smart agriculture, in a farm field, inside a vinyl house, and between the base station and farm fields, and evaluated signal attenuation as a function of distance and the variability of RSSI by analyzing signal data. We measured the decay characteristics of the signal in a farm where crops and other obstacles exist along the radio wave’s propagation path. In addition, we characterized the variation of RSSI in a farm, where obstacles exist near the transmitter or receiver nodes and crops exist along the radio wave’s propagation path.
To produce high-quality wine in vineyards, it’s necessary to understand the characteristics of the cultivation environment. This knowledge is obtained through long-term monitoring. To provide this knowledge, we developed a new wireless sensor network (WSN) that could be used to monitor the vineyard growing environment. To support the use of this data, we developed a Web-based application to help growers take advantage of the information obtained on cultivation conditions. In the WSN, we adopted the 920 MHz band that is used in the Wi-SUN standard (to replace the older 2.4 GHz band) to obtain data from a weather station and soil moisture sensors. In the WSN data-acquisition method, data was standardized using a predetermined name for each sensor and standardized measurement units. The accuracy of the acquired weather station data was verified by comparison with data from a nearby Japan Meteorological Agency weather station. The Web application let growers improve cultivation management using data on the growing environment, such as the cumulative growing degree-days (GDD), growing season temperature (GST), cool-night index (CI), heliothermal index (HI), biologically effective degree-days (BEDD), and dryness index (DI).
April 03, 2017 There had been a system trouble from April 1, 2017, 13:24 to April 2, 2017, 16:07(JST) (April 1, 2017, 04:24 to April 2, 2017, 07:07(UTC)) .The service has been back to normal.We apologize for any inconvenience this may cause you.
May 18, 2016 We have released “J-STAGE BETA site”.
May 01, 2015 Please note the "spoofing mail" that pretends to be J-STAGE.