Decagon Devices MAS-1 Podręcznik użytkownika - Strona 15
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5. Calibration
The current transmitted by the MAS-1 is proportional to the
dielectric permittivity of the medium surrounding the sen-
sor, and therefore its volumetric water content (VWC) of the
medium. The VWC is calculated by applying a calibration
equation to the current transmitted by the MAS-1. The fol-
lowing are generic calibration equations for common growth
media. Applying these equations will generally result in
accuracy of ± 4% VWC as long as the electrical conductiv-
ity of the medium is less than 8 dS/m. If you wish to use the
MAS-1 in a medium that isn't listed below, if you need bet-
ter than ± 4% accuracy, or if you are working in a high salin-
ity material, then you should develop a custom calibration
for your particular medium. See www.decagon.com for
step-by-step instructions on developing a custom calibra-
tion. Decagon can also develop a custom calibration for
your medium; contact Decagon for more details on the cali-
bration service.
Mineral Soils
A single calibration equation will generally result in good
accuracy for all mineral soil types with electrical conductiv-
ity < 8 dS/m. VWC is given by:
VWC = 0.00328 * mA
If your data acquisition system isn't capable of higher order
mathematical operations, the mineral soil calibration can be
MAS-1 Soil Moisture Sensor
2
- 0.0244 * mA - 0.00565
12
5. Calibration