User Manual
SONO-MIX MINI Version 2_7
2017-05-12
Page 18
3. Calibration Curves
SONO-MIX MINI is supplied with the calibration curve
Cal9 MIX
for the mixer operation with sand and
gravel.
Cal9 MIX
is slightly increased in the dry measurement range to ensure that in dry sand and
gravel, the readings do not move to 0% values, because values around 0% can be disadvantageous for
the filter arithmetic. So in dry sand/gravel the readings of the SONO-MIX MINI show higher
measurement values. For an absolute value calculation for the water addition into the mixer it is
important to take this into account. In general, the calibration of the probe for the water addition by a
PLC has to be determined with laboratory measurement methods (oven drying).
A maximum of 15 different calibration curves (Cal1 ... Cal15) are stored inside the SONO probe and can
optionally be activated via the program
SONO-CONFIG
. If SONO-MIX MINI is used without mixer
operation, only for measuring the moisture content of aggregates like sand and gravel, then the
calibration curve Cal. 1 (Universal Sand Mix) must be set. If SONO-MIX MINI isn´t used inside a mixer
but e.g. beneath a flap, the operation mode must be changed from CK to CA.
A preliminary test of an appropriate calibration curve (Cal1. .15) can be activated in the menu
"Calibration"
and in the window
“Material Property Calibration"
by selecting the desired calibration
curve (Cal1...Cal15) and with using the button
“
Set Active Calib
”. The finally desired and possibly
altered calibration curve (Cal1. .15) which is activated after switching on the probes power supply will be
adjusted with the button "
Set Default Calib
”.
Nonlinear calibrations are possible with polynomials up to 5th grade (coefficients m0 to m5).
IMKO publish on its website more suitable calibration coefficients for different materials. These
calibration coefficients can be entered and stored in the SONO probe by hand (Cal14 and Cal15) with
the help of SONO-CONFIG.
The following charts (Cal.1 .. 15) show different selectable calibration curves which are stored inside the
SONO probe.
On the y-axis the gravimetric moisture (
MoistAve
) is shown. On the x-axis depending on the calibration
curve the associated radar time
tpAve
in picoseconds is shown. With the software
SONO-CONFIG
the
radar time
tpAve
is shown on the screen parallel to the moisture value
MoistAve
(see "Quick Guide for
the Software SONO-CONFIG).
