2017-05-30
Manual TRIME_PICO64-32 Version 2_0
Page 35
11.10
Creating a linear Calibration Curve for a specific Material
The calibration curves Cal1 to Cal15 can be easily created or adapted for a specific soil with the help of PICO-
CONFIG. Therefore, two measurement points need to be identified with the probe. Point P1 at dried soil and
point P2 at moist soil where the points P1 and P2 should be far enough apart to get a best possible calibration
curve. The moisture content of the soil at point P1 and P2 can be determined with laboratory measurement
methods (oven drying). It is to consider that sufficient material is measured to get a representative value.
Under the menu
"Calibration
" and the window "
Material Property Calibration
" the calibration curves CAL1 to
Cal15 which are stored in the PICO probe are loaded and displayed on the screen (takes max. 1 minute). With
the mouse pointer individual calibration curves can be tested with the PICO-probe by activating the button "
Set
Active Calib
". The measurement of the moisture value
Moist
with the associated radar time
tp
at point P1 and
P2 is started using the program PICO-CONFIG in the sub menu "
Test
" and "
Test in Mode A
".
Step 1:
The radar pulse time
tp
of the probe is measured with dried soil. It is recommended to detect multiple
measurement values for finding a best average value for
tp
. The result is the first calibration point P1 (e.g.
70/0). I.e. 70ps (picoseconds) of the radar pulse time
tp
corresponds to 0% moisture content of the material.
But it would be also possible to use a higher point P1´ (e.g. 190/7) where a
tp
of 190ps corresponds to a mois-
ture content of 7%. The gravimetric or volumetric moisture content of the material, e.g. 7% has to be deter-
mined with laboratory measurement methods (oven drying).
Step 2:
The radar pulse time
tp
of the probe is measured with moist material. Again, it is recommended to
detect multiple measurement values of
tp
for finding a best average value. The result is the second calibration
point P2 with X2/Y2 (e.g. 500/25). I.e.
tp
of 500ps corresponds to 25% moisture content. The gravimetric or
volumetric moisture content of the material, e.g. 25% has to be determined with laboratory measurement
methods (oven drying).
Step 3:
With the two calibration points P1 and P2, the calibration coefficients m0 and m1 can be determined
for the specific soil (see next page).
Step 4:
The coefficients m1 = 0.0581 and m0 = -4.05 (see next page) for the calibration curve Cal15 can be en-
tered directly by hand and are stored in the probe by pressing the button “
Set
”. The name of the calibration
curve can also be entered by hand. The selected calibration curve (e.g. Cal15) which is activated after switching
on the probes power supply will be adjusted with the button "
Set Default Calib
”.
Attention:
Use “dot” as separator (0.0581), not comma !
11.10.1
Calculation for a linear 2-point calibration curve
1. Download the Excel-Sheet
„SONO 2-Point LinearCalibration_Calculation“
from IMKO´s
Homepage under „Support Software“.
2. Enter into the Excel-Sheet both TP-values with the respective reference moisture values.
3. Read out both parameters m0 and m1 from the Excel-Sheet.
4. Enter, set and s
ave both parameters m0 and m1 with help of the software „SONO-CONFIG“
in the menu „
Calibration
“ in the window „
Material Property Calibration
“ in the selected cal-
ibration curve.
Содержание TRIME-PICO 32
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