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The level signal can be optimized upon two factors:
Amplification factor
The amplitude of the signals is proportional to the dielectric constant
r
of the medium. At low amplitudes the signal should be amplified. The amplification factor is
depend on the dielectric constant
r
and on the probe type. The device sets gain automatically.
The following factors apply to the set gain:
Gain
Amplification factor
0 1.05
1 2.10
2 4.37
3 8.93
Level threshold
The level threshold suppresses interference signals so that only the reflections from the medium surface (level signal) are shown. The factory setting of the level
threshold is suitable for standard applications.
The threshold has to be adjusted in case of very low dielectric constants
r
, multiple interference reflections or unfavourable installation conditions.
The illustrations below show interference signals when the oscilloscope function is used.
These reflections can be due to various causes, e.g. tank internals or multiple reflections within the measuring range.
Even if interference signals very weak, threshold should never be set higher than the
following signals:
1 Initial
pulse
2 Flange
reflection
3 Level
signal
4 Interference
signal