Accuracy among devices
| Max error |
-0.5 ... +0.5 |
| Mean error |
0.2 |
| Std Dev on error |
0.2 |
How it is evaluated
All devices are calibrated and, using two different filters, measured at reference values 31.8 and 65.3.
The accuracy for device i is evaluated as :
Errori = ( ( M1i - 31.8 ) + ( M2i - 65.3)) / 2
where
M1i is the measure value of device i with filter at 31.8 and
M2i is the measure value of device i with filter at 65.3
Maximum error
N ... number of produced devices
maximum positive error = for (i=0 to N) maximum(Errori)
maximum negative error = for (i=0 to N) minimum(Errori)
Mean error
mean error = (abs(Error0) + abs(Error1) + .. + abs(ErrorN)) / N
Std Dev on error
Std Dev on error = sqrt ( (sum (Errori - mean error)2) /N )
Repeatability
Tested on 303 measures with an optical filter.
How it is evaluated
The measures are performed remotely with atLEAFSoft PRO software, with the atLEAF CHL PRO connected through a USB port.
For this test the period among measures is set to 2s, while the available software has a minimum selectable period of 10s.
The sample used for evaluating the instrument repeatability is an optical filter.
View the video of the test.
Repeatability on a green plant
A similar test was also performed on a living green plant (Pothos, Epipremnum aureum).
The leaf was not moved during the test and the measures were made with a period of 2s
(while available atLEAFSoft version allows remote acquisitions with a minimum
period of 10s). After a series of 100 measures, the reported series of 200 measures was performed.
The results were: