Sensor Webs

Notable features would include flexibility of deployment, low power consumption, and low cost.

Sensor webs are developmental collections of sensor pods that could be scattered over land or water areas or other regions of interest to gather data on spatial and temporal patterns of relatively slowly changing physical, chemical, or biological phenomena in those regions. Each sensor pod would be a node in a data-gathering/ data-communication network that would span a region of interest. Each sensor pod would contain two modules: (1) a transducer module that would interact with the environment to gather the desired data and (2) a communication module.

The basic concept of a network of sensors is not new. The novelty of the sensor-web concept lies in exploitation of a confluence of advances in integrated circuits for radio communication, wireless-network communication technology, and cheap micromachined sensors. This exploitation takes the form of a design concept that affords flexibility of configuration and operation of networks while minimizing power consumption.

A sensor web would contain a few primary nodes and many secondary nodes. Data would be transferred from node to node within the network. The primary nodes would have the additional capability and task of communicating signals into and out of the sensor web: For example, at a primary node, sensory data gathered by the web could be transmitted to an overhead aircraft or satellite or to a local field computer.

Inasmuch as the power needed for intraweb transfer of data increases with the bandwidth of the sensor signals, the sensor output signals should be of low bandwidth to make it possible to minimize power consumption in the sensor pods. Fortunately, many natural phenomena that one might wish to monitor (e.g., temperature or concentrations of chemicals) are inherently of low bandwidth. In cases of phenomena that vary more rapidly, it could be necessary to compress the sensor data at the nodes before transmission.

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