Campbell NR-Lite Instruction Manual - 5. Datalogger Programming
NR-LITE Net Radiometer
9
5. Datalogger Programming
The NR-LITE outputs a low-level voltage ranging from 0 to a maximum of
about 15 mV. A differential voltage measurement (Instruction 2) is
recommended because it has better noise rejection than a single-ended
measurement. If a differential channel is not available, a single-ended
measurement (Instruction 1) can be used. The acceptability of a single-ended
measurement can be determined by simply comparing the results of single-
ended and differential measurements made under the same conditions.
5.1 Datalogger Input Range Codes
Normally the 15 mV range for the 21X and CR7, the 25 mV range for the
CR10(X) and CR500/CR510, and the 50 mV range for the CR23X are suitable.
The parameter code for the input range also specifies the measurement
integration time. The slow or 60 Hz rejection integration gives a more noise-
free reading. A fast integration takes less power and allows for faster
throughput.
5.2 Calibration Factor
Each NR-LITE is provided with a ‘Certificate of Calibration’ by the
manufacturer which shows the sensor serial number and a ‘sensitivity’ or
calibration factor. This calibration factor, after conversion, is used in the
datalogger program. Always cross check to ensure that the serial number of
your NR-LITE and the number on the calibration certificate are identical. The
serial number and sensitivity are also shown on a small label attached to the
connecting arm near the head of the sensor itself.
The calibration factor provided by Kipp & Zonen is in units of uV/(W m
-2
),
which needs to be converted to units of (W m
-2
)/mV for the multiplier
parameter in the datalogger program. To convert the units, divide the
calibration factor into 1000. For example, if the calibration factor is 15.8
uV/(W m
-2
), the multiplier is:
1000/15.8 = 63.29 (W m
-2
)/mV
5.3 Example Programs
5.3.1 Example 1, CR10(X) Program without Wind Speed Correction
Shown below is an example program written for the CR10(X) datalogger. The
datalogger measures the output from the sensor every 60 seconds and outputs
the average net radiation every hour.
The calibration factor used will only apply for one specific sensor. A new value
will need to be calculated for every different sensor based on the certificate of
calibration for that sensor (see above).