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7 Calibrating
Before calibration it is important to set the initial sensor configuration (as it is
described preliminary in chapter 5).
7.1 Sampling
For calibration it is necessary to take samples during the whole process and
evaluate them in the laboratory. While sampling the process has to be in stable
conditions. There should be taken a minimum of 5 to 8 samples, which are coping
the complete measuring range.
Example for sugar industry:
For batch pans it is recommended to take 3 samples before seeding point and at
least 5 after.
For each sample note following data:
•
Date and time of sample taking
•
Displayed main value (in corresponding unit)
•
Phase shift (P in °)
•
Temperature (T in °C)
•
Compensated phase shift (P-comp in °)
•
Level (L in dBm)
•
Attenuation (in dB)
•
Volts (in V)
You can either note these values manually or simply switch on data log to record
them on the integrated SD card. Additionally there is a sample push-button
available to mark the logged data while taking the sample.
7.2 First calibrating
After sampling, enter these values to the excel file “IBN” in the corresponding
columns and add the laboratory values to the field „labor (Y-Axis).
With these values the new settings will be calculated. Samples which are not
used for the calibration but should be removed in the field „Labor not used“. The
further columns are only for the calculation and may not have to be changed.
They
only
have
to
be
copied
downwards.
In addition you have to enter the initial settings such as A0, A1, ref-point and p-
offset (previously entered settings).
The new settings (A0, A1) are automatically calculated and can be read off in the
sheet “calibration data” and also in the sheet “trend” (form: Y = a1 * x + a0 and
the correlation coefficient R^2).
