Campbell Scientific CNR4 Net Radiometer - Manual (Page 29)

CNR4 Net Radiometer
7.3 Datalogger Pro ming
single-ended measurement. If differential channels are not available, single-
ptability of a single-ended
ed by simply comparing the results of single-
y,
7.3.1 Sensor Sens
rate
nufacturer. They show the sensor serial number and
sensitivity values for four individual probes: one copy for pyranometers, and
y for pyrgeometers. The serial number and sensitivity values are
on a label affixed to the bottom of the sensor. If you choose to
CNF4
.
7.3.2 Example Pro
7.3.2.1 Example 1, CR
ur differential channels to measure the four radiation
outputs, one excitation channel, and one single-ended channel to measure the
he program measures the sensors every 1 second, performs the
ssing of the data, and stores the following processed data to a data
es the raw time-series
ometer up)
Average long-wave radiation (pyrgeometer down)
temperature (degrees C)
(Kelvin)
eter up)
wn)
gram
The CNR4 outputs four voltages that typically range from 0 to 15 mV for the
pyranometers, and
± 5 mV for the pyrgeometers. A differential voltage
measurement is recommended because it has better noise rejection than a
ended measurements can be used. The acce
measurement can be determin
ended and differential measurements made under the same conditions.
Additionally, one voltage excitation channel and one single-ended analog
channel are required to make the temperature measurement of the sensor bod
using the thermistor.
itivity
The CNR4 comes with four different sensor sensitivity values for four sepa
probes. The CNR4 sensor comes with two copies of its ‘Certificate of
Calibration’ by the ma
another cop
also shown
attach the CNF4 heater/ventilator unit to the CNR4, the label showing the
serial number and sensitivity values will be covered. After attaching the
heater/ventilator, affix the extra label to the bottom of the CNF4 in a visible
location. The extra label containing the serial number and sensitivity values is
supplied with the purchase of the CNR4. Please refer to Appendix B, CNF4
Heater/Ventilator, for more details.
The sensor sensitivity is in μV/(W/m 2 ). This needs to be converted into
(W/m 2 )/mV to be used as a multiplier parameter inside the datalogger program
To convert the units, divide the sensor sensitivity value into 1000. For
example, if the sensitivity is 7.30
μV/(W/m 2 ), the multiplier is 1000/7.3 =
136.99 (W/m 2 )/mV.
grams
1000 Program Using Differential Measurements
Example 1 requires fo
thermistor. T
online proce
table called cnr4_data once every 60 minutes. It also stor
data from CNR4 to data table called cnr4_ts.
Minimum battery voltage
Sample datalogger panel temperature
Average short-wave radiation (pyranometer up)
Average short-wave radiation (pyranometer down)
Average long-wave radiation (pyrge
Average CNR4 thermistor
Average CNR4 thermistor temperature
Average corrected long-wave radiation (pyrgeom
Average corrected long-wave radiation (pyrgeometer do
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