Habitat and environment monitoring with wireless sensors

Habitat and environment monitoring is one of the area that get the benefit of wireless sensor networks. Because the nature of the Sensor is ideal for the habitat monitoring. Tiny sensor help to deploy the device in manageable space. It has the capability of long term data collection. Integration of local processing and data give the ideal situation for the habitat and environment monitoring. Each sensor provides the unique information about the environment

Infrared Temperature Sensors

Infrared (IR) radiation is part of the electromagnetic spectrum,which includes radio waves, microwaves, visible light, and ultraviolet light, as well as gamma rays and X-rays.

The IR range falls between the visible portion of the spectrum and radio waves. IR wavelengths are usually expressed in microns, with the lR spectrum extending from 0.7 to 1000 microns. Only the 0.7-14 micron band is used for IR temperature measurement.

Using advanced optic systems and detectors, noncontact IR thermometers can focus on nearly any portion or portions of the0.7-14 micron band. Because every object (with the exception of a blackbody) emits an optimum amount of IR energy at a specific point along the IR band, each process may require unique sensor models with specific optics and detector types.

For example, a sensor with a narrow spectral range centered at 3.43 microns is optimized for measuring the surface temperature of polyethylene and related materials. A sensor set up for 5 microns is used to measure glass surfaces. A 1 micron sensor is used for metals and foils. The broader spectral ranges are used to measure lower temperature surfaces, such as paper, board, poly, and foil composites.

source : http://www.sensorland.com/HowPage022.html

How Wireless Sensor Works...

A wireless sensor is much similar to the computer. A mote consisted with 3 main parts. 1- a mini computer, 2- a sensing device, 3- a radio transmitter.

The radio communication of crossbow motes are described as follows.
(visit http://www.xbow.com/Technology/RadioCommunication.aspx)

"The radio technology used in Crossbow’s wireless modules supports domestic and international frequency bands in the 433 MHz, 868-915 MHz, and 2.4 GHz bands. Multiple channels are available in each band under software control, resulting in a flexible solution for customer applications. Two modulation formats are available, two-tone Frequency-Shift-Keyed (FSK) at 433 and 868-915 MHz, and direct sequence spread spectrum (DSSS) at 2.4 GHz supporting the 802.15.4/ZigBee standard. All radios are bidirectional (half-duplex), and support a range of 30 to 1000 feet (10 to 100 meters) using XMesh with low-power protocol and battery-life time of 5 plus years in commercial applications. Transmit power levels are software controlled to enable end users to comply with local government regulations for frequency transmission.

The processor has full control of radio features, and can control parameters such as transmit/receive mode switching, channel selection, output power, and radio standby mode. Data packets routed through the radio are error correction encoded, with the ability to listen to the channel via RSSI measurement to determine if the channel is clear to send data. Depending on choice of radio and configuration, data rates of 19.2kbps to 240kbps are available. Both the radio and processor support deep sleep modes for maximum power savings. The motes are designed to support battery operation from 2.4V to 3.6V, with an integral battery voltage monitor."

sensing devises are the sensor boards which we can plug in to the mote. We can plug several sensor boards to single mote and it enables multiple sensing capability to the sensor. Sensor board is consisted with one or more sensors. Humidity, temperature, light, acoustic and many more sensors are available.

Sensor networks for all...

Wireless sensor is a kind of a transducer which senses the physical world facts like temperature, light, humidity, magnetic field and many more. It is capable of data gathering, processing, storing and communicating. Recent advances in wireless sensor networks has enabled the development of low cost, low-power, multifunctional sensor nodes that are small in size and communicate short distances. Therefore this technology is currently used in many areas and can be used in many areas. The major difficulty which is faced by the people in different domains is programming of the sensor nodes. The user has to program the sensor nodes using “nesC” programming language. To do that, users should have good nesC knowledge and programming practice. It is not practical we expect sound programming practice from a user not in computer science domain. It is very easy if those users have a higher level abstract configuration environment for configure sensors in their applications.