EC-20, EC-10 and EC-5 User’s Manual
4. Collecting Data
16
sensors connected to a non-Decagon datalogger you will
need to use the 2500 mV calibration. If you use any
Decagon software (DataTrac, ECH
2
O Utility, etc.) or
the user calibration menu in the ECH
2
O Check, you will
need to use the RAW calibration. The difference
between the two is the slope constant. To increase the
resolution of the sensor output, Decagon uses all avail-
able increments of the 12-bit number (value of 4096)
where the measurement is stored. Thus, the output of the
sensors read by the ECH
2
O Check and Decagon loggers
must be multiplied by 0.61 AND the 2500 mV slope to
give the right value.
Sensor Calibration Values
Following is a list of the both the millivolt and RAW
calibration values for the EC-20, EC-10 and EC-5,
where
is the volumetric water content, mV is the milli-
volt output of the sensor, and where
x
is the RAW sen-
sor output.
EC-20:
mV:
(m
3
/m
3
) = 0.000695mV - 0.29
RAW:
(m
3
/m
3
) =0.000424 x - 0.29
EC-10:
mV:
(m
3
/m
3
) = 0.000936mV - 0.376
RAW:
(m
3
/m
3
) = 0.000571 x - 0.376
EC-5:
The EC-5 is much less sensitive to variation in texture
and electrical conductivity because it runs at a much
higher measurement frequency. Therefore, its general
calibration equation should apply for all mineral soils up
