Campbell Scientific Wireless Sensor Network (CWB100, CWS220, and CWS900) - Manual (Page 11)

Wireless Sensor Network
1.3 CWS220 Wireless Infrared Radiometer
The CWS220 is a Wireless Infrared Radiometer that incorporates Apogee
Instrument's SI-111 infrared sensor to provide a non-contact means of
measuring the surface temperature of an object. It senses the infrared radiation
being emitted by the target. The CWS220 is used to measure leaf, canopy, and
average surface temperature. Contact sensors have difficulty making
measurements without influencing the temperature, maintaining thermal
contact, and providing a spatial average.
The CWS220 is mounted at an appropriate distance from the target where it
can measure an individual leaf, a canopy, or any surface of interest. Because
the CWS220 is wireless, it can be mounted in many locations that would be
problematic for a cabled sensor.
The CSW220 includes a thermopile for measuring a millivolt output dependent
on the target to sensor body temperature difference. A thermistor measures the
temperature of the sensor body. The sensor body temperature is used to
reference the target temperature.
The calibration coefficients used for determining the target temperature by
means of the Stefan-Boltzman equation are stored in the CWS220 at the time
of calibration.
FIGURE 1.3-1. CWS220 Wireless Infrared Radiometer
The CWS220 outputs 5 values: Target temperature, Sensor body temperature,
Internal temperature, Battery Voltage, and Signal strength.
Additional detail regarding CWS220 output is available in Appendix B.
For specifications of the CWS220, see Section 2.3.
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