Delta-T Devices SunScan SS1 User Manual page 47


In SunData on the PDA select Utilities, Calibrate, Recalibrate
SunScan, then follow the instructions.
You should not expect to have to do this very often. The photodiodes and
light measurement circuits are very stable.
The sources of the apparent variability mentioned above, between the
probe and BF5, are

the not quite ideal cosine and spectral responses of the sensors

any dirt and grime that builds up on the on the SunScan diffuser (so
keep it clean).
You cannot recalibrate the probe when using the radio link. (The function
is disallowed because the light levels may not be the same.)
Restoring the factory calibration
At any time after carrying out the Recalibrate option you can restore the
original factory calibration. You do not have to set up the probe or BF5 in
uniform light.

In SunData on the PDA Select Utilities, Calibrate, Restore Factory
Calibration.
You will briefly see a message confirming that this has been done.
Comparing the calibration with other PAR sensors
You can carry out matching comparisons between the probe and BF5 and
any other PAR quantum sensor. You cannot reset the probe values to it,
but you can annotate the readings and retain the comparison information
in the SunScan data files.
The "Spread" measurement
The "Spread" value is a measure of the relative variation of the light along
the probe. This is a useful parameter in light profiling measurements: it is
the value of the standard deviation of the 64 photodiode readings,
divided by their mean.
You can check the probe uniformity of calibration at any time by taking a
reading in uniform light. The spread value should be 0.00 or 0.01.
SS1 User Manual v3.3
What to Measure and How  47