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16. Special functions
16.1.1. Determination of the mineral concentration
With the radar-based TRIME measurement method, for the first time ever it is now possible
not only to measure moisture but also to draw conclusions about the conductance or mineral
concentration. Here, the system determines the attenuation of the radar pulse in the measured
volume fraction of a material. This novel and innovative measurement method delivers a radar-
based conductance value (RbC – Radar-based-Conductivity) in mS/cm as the characteristic value,
which is determined depending on the mineral concentration and is output as an unscaled value.
The conductivity measuring range of SONO GS1 probes is up to 0 to 12mS/cm, depending on the
moisture content.
16.1.2. Material temperature measurement
The SONO GS1 probe contains an integrated temperature sensor, which determines the housing
temperature 3mm below the surface of the probe head. The temperature can optionally be output
at analog output 2. As the probe electronics operate with a power of approx. 1.5W, the probe
housing heats up slightly. Therefore a very precise measurement of the material temperature is
not possible, or is only possible to a certain degree. With the device installed and with good heat
distribution conditions throughout the system, the material temperature can, however, be
determined following an external calibration and compensation of the sensor's self-heating.
The temperature offset value resulting from the self-heating can be adjusted using the
SONO-CONFIG program.
16.1.3. Temperature compensation when used at elevated temperatures
SONO probes are generally not easily affected by temperature. Nevertheless, there are
applications where temperature compensation is necessary. SONO probes offer two ways to
perform temperature compensation.
16.1.4. Temperature compensation of internal SONO electronics
This temperature compensation function can compensate for a temperature drift of the
SONO electronics. As the SONO electronics are generally not easily affected by temperature,
the standard parameter TempComp=0.2 is preset in every SONO probe for "normal" ambient
temperature ranges. This TempComp parameter can be set to values up to TempComp=0.75 for
operation at high temperatures, which can be up to 80°C (176°F) depending on the SONO probe
type. However, if the parameter TempComp is changed by >0.2, it is recommended to perform a
basic calibration in water and air with the SONO probe. The TempComp parameter can be set
with the SONO-CONFIG software tool in the "Calibrations" item and the "Electronic-Temperature-
Compensation" menu.
Caution: If the TempComp parameter is changed, the basic calibration of the
probe also changes, which is why a new basic SONO probe calibration is then
needed!
16.1.5. Compensation of the temperature of the material being measured
When used in higher temperature ranges, the dielectric constant (DC) of water and certain
materials being measured shows a temperature dependency. Moisture is determined using the
dielectric constant, i.e. the DC is the actual parameter measured during moisture measurement
with SONO probes. If materials being measured, such as maize, show a very special temperat ure
dependency of the DC, such as a temperature dependency only in very specific moisture ranges,
it may be necessary to perform much more complex temperature compensation which involves a
Endress+Hauser
MMP60 SONO GS1
Page 27
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