Campbell CM 21, Инструкция по эксплуатации, Страница: 11 / 65

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Before leaving the factory, the cosine response of each CM 21 is measured.
At four zenith angles the cosine response versus two azimuth’s is
determined.
These values (40º and 70º) are stated on the calibration certificate,
expressed as percentage deviation from the ideal proportionality and as
absolute values (see appendix IV).
1.2.4 Low temperature dependency of sensitivity
The sensitivity is correlated to the temperature as a consequence of physical
material properties of the sensor. For a given heat flow, the sensitivity of the
pyranometer is a function of the thermal conductivity of the sensor and of the
thermo-electric power of the thermocouple material. Both physical
parameters show temperature dependency.
Due to the sensor construction and applied thermistor compensation circuit
the temperature response is suppressed to a minimum between –20ºC and
+50ºC.
During factory manufacturing the sensitivity of each CM 21 pyranometer is
measured and compensated to provide the temperature dependency
specifications.
The temperature dependency is supplied with each instrument, measured in
8 steps of 10ºC, from +50ºC to –20ºC.