Campbell Scientific SP-LITE Solar Radiation Sensor - Manual (Page 12)

SP-LITE Silicon Pyranometer
8
5.1 Datalogger Input Range Codes
Normally the 15 mV range for the 21X and CR7, the 25 mV range for the
CR10(X), CR500/CR510, and CR1000, 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. Measurement instructions for the CR1000 have a separate
parameter for the integration time.
5.2 Calibration Factor and Multiplier
All SP-LITE sensors have a sensitivity, or calibration factor, of 1
0 µV/(W m -2
).
Solar radiation can be reported as an average flux density (W m
-2 ) or daily total
flux density (MJ m -2 ). The appropriate multipliers for the measurement
instruction are listed in Table 3. Programming examples are given for both
average and daily total solar radiation.
TABLE 3. Multipliers Required for Flux Density and Total
Fluxes
Units Multipliers Output Processing
MJ m -2 t*0.0001 (P72 total fluxes)
KJ m -2 t*0.1 (P72 total fluxes)
W m -2 100 (P71 flux density)
KW m
-2
0.1 (P71 flux density)
cal cm
-2
t*0.0239*0.1 (P72 total fluxes)
cal cm
-2
min
-1
1.434*0.1 (P71 flux density)
t = the datalogger program execution interval in seconds
5.3 Program Example 1, Average Solar Radiation
The examples below give the appropriate datalogger code for the CR10X
datalogger, using either Instruction 2 (differential) or Instruction 1 (single-
ended).
Example 1 shows the program instructions used to measure the signal from the
SP-LITE. A thirty-minute average is calculated and stored in final storage.
Wiring for Example 1
Color Function
Example CR10X
Program Channels
Used
White Radiation Signal 1H
Green Signal Reference 1L
Jumpered to AG
Clear Shield G