Campbell Scientific CMP6-L, CMP11-L, and CMP21-L Pyranometers - Manual (Page 14)

CMP6-L, CMP11-L, and CMP21-L Pyranometers
5. Overview
5.1 Models
CMP-series models differ in accuracy and performance. See Section 6,
Specifications. The CMP21 also includes an internal thermistor allowing
individually optimized compensation of the measurements. The –L portion of
the model number indicates that the pyranometer has a user-specified cable
length. The pyranometers have several cable termination options. Their cables
can terminate in:
• Pigtails that connect directly to a Campbell Scientific datalogger
(cable termination option –PT).
• Connector that attaches to a prewired enclosure (cable termination
option –PW).
• Connector that attaches to a CWS900 Wireless Sensor Interface (cable
termination option –CWS). The CWS900 enables the pyranometer to
be used in a wireless sensor network. Please note that this option is
not available for the CMP21.
5.2 Construction
The pyranometers consist of a thermopile sensor, housing, two glass domes,
and cable. The thermopile is coated with a black absorbent coating. The paint
absorbs the radiation and converts it to heat. The resultant temperature
difference is converted to a voltage by the copper-constantan thermopile. The
thermopile is encapsulated in the housing in such a way that it has a field of
view of 180 degrees and the angular characteristics needed to fulfill the cosine
response requirements.
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