Wireless but not clueless
Box 2 | Remote sensors and their applications
For a long time, environmental scientists have braved extreme conditions – high altitudes, rough seas, steep terrain, isolation, rain, snow and wild animals – to gather the data they need to understand natural phenomena. They may need less bravery in the future: wireless sensor networks (WSNs) are taking some of the adversity out of their jobs and simultaneously sparking rapid advances in environmental science.
The sensors of a WSN are little different to those used for years by environmental scientists. They measure parameters such as temperature, humidity, precipitation, soil moisture, groundwater or stream levels, salinity, carbon dioxide, oxygen and pH, and they might also record sounds or visual images.
In the past, the data gathered by these sensors had to be downloaded manually, requiring a scientist, technician or student to visit the site. This was not only time-consuming, costly and sometimes dangerous, it meant that data often were quite old by the time they were collected. Wireless technology is revolutionising the role of environmental sensors by enabling the remote, automatic processing and transmission of environmental data in real time to a scientist sitting in a lab, office or cybercafe.
The WSNs comprise arrays of sensors placed in the field. Micro-processors built into the sensors convert the measurements of these parameters to a digital format, process the data and convert them to radio signals. A radio transmitter then sends the data to a base station, possibly via other sensors that act as nodes in the network in a way similar to WiFi meshing, where the data can be uploaded onto the internet or other computer network. If the sensors are also equipped with receivers, scientists can adjust the nature of the data collected, the periodicity of transmissions and other parameters, without needing to continually venture into the field. The cost-effectiveness of WSNs means that the number of monitoring sites can be greatly increased at minimal cost.
Deployment of WSNs is beginning in Australia. Scientists at the CSIRO Information and Communication Technologies Centre in Brisbane have developed a hardy, low-cost WSN called Fleck. This small, solar-powered device has a radio range of 500 metres or more, which can be extended to many kilometres when part of a network of similar devices. Various sensors, measuring such things as temperature, humidity, stream levels and other parameters of environmental quality, can be connected to the Fleck and their data collected, processed and transmitted.
The range of possible uses to which WSNs such as Fleck can be put is almost as diverse as the environment itself. One important use already envisaged in Australia is detailed monitoring of the water supply. WSNs could be used to track and predict water quality and quantity at different time-scales, from minute to minute and year to year. Others see WSN applications in agriculture: a property-level WSN could provide farmers with timely information on soil moisture, ambient weather, and even livestock condition, reducing the guesswork needed to manage the land efficiently. Ecologists could put WSNs to good use as one of their great challenges is to collect and analyse sufficient data to fully understand the way ecosystems function. These WSNs may be the key to unlocking many of nature's biggest secrets.
Boxes
Box 1. Hotspots and meshes
Box 3. Security and encryption
Box 4. Increasing speed
Box 5. Competition
Related sites
Can a government remotely detect a terrorist’s thoughts? (New Scientist, 11 August 2007)
Keeping check with Flecks (CSIRO, Australia)
Wireless sensor networks for ecology (Coral Reef Environmental Observatory Network)
Page updated August 2007.