Emerson Rosemount 5408 Reference Manual page 114

Service and Troubleshooting
Add or delete an amplitude threshold point
1.
2.
Suppressing false echoes
Stationary objects with horizontal surfaces may generate strong false echoes. When the
surface is close to an obstruction in the tank (e.g. beams and agitators), the surface and
false echoes might interfere and cause a decrease in performance.
However, false echoes can be suppressed to reduce the influence of such objects, in case
they cannot be totally avoided. When the surface is passing by a disturbing object, the
transmitter will then measure with higher reliability, even if the surface echo is weaker
than the false echo, see
Figure 7-6:
A.
B.
C.
D.
E.
104
In the echo curve, select the desired amplitude threshold point, and select Split
threshold or Merge with threshold below.
Click again on one of the amplitude threshold points and select Save.
Figure 7-6.
Suppression of False Echoes
Amplitude threshold
Disturbing object
False echo suppression
Suppressed echo
Surface
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