Decagon Devices MAS-1 Посібник користувача - Сторінка 7
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MAS-1 Soil Moisture Sensor
2. About the MAS-1
2. About the MAS-1
The MAS-1 measures the dielectric constant of the soil in
order to find its volumetric water content. Since the dielec-
tric constant of water is much higher than that of air or soil
minerals, the dielectric constant of the soil is a sensitive
measure of water content. The MAS-1 supplies a 70 MHz
oscillating wave to the sensor prongs that induces an electro-
magnetic field in the medium (soil) surrounding the sensor.
The charging and discharging of the sensor is controlled by
the dielectric of the surrounding soil.
A microprocessor on the MAS-1 measures the charging of
the sensor, and therefore the dielectric constant of the soil
which is related to the water content of the soil. The micro-
processor makes a dielectric measurement and updates the
transmitted current once per second. The transmitted 4-20
mA current can be converted to the water content of the soil
using a simple calibration function.
The MAS-1 was designed to be used with standard 4-20 mA
controllers and monitoring systems. It cannot be used with
Decagon logging systems. For more information about
using Decagon logging systems please contact Decagon's
customer support representatives.
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