Echo Lock; Auto False Echo Suppression - Siemens 7ML5431 Operating Instructions Manual

Appendix A: Technical reference
A.2 Echo Processing
A.2.5

Echo Lock

If the echo selected by Algorithm is within the Echo Lock window, the window is centered
about the echo, which is used to derive the measurement. In radar applications, two
measurement verification options are used with Echo Lock (2.8.5.1.):
Lock Off
SITRANS LR250 responds immediately to a new selected echo (within the restrictions set by
the Maximum Fill / Empty Rate), but measurement reliability is affected.
Material Agitator
A new measurement outside the Echo Lock Window must meet the sampling criteria before
the window will move to include it.
The other available options, Maximum Verification and Total Lock are not recommended for
radar.
A.2.6

Auto False Echo Suppression

Note
• For detailed instructions on using this feature via PDM see Auto False Echo Suppression
(Page 80).
• For detailed instructions on using this feature via the handheld programmer see Auto
False Echo Suppression (2.8.7.1.).
Auto False Echo Suppression is designed to learn a specific environment (for example, a
particular vessel with known obstructions), and in conjunction with Auto False Echo
Suppression Range to remove false echoes appearing in front of the material echo.
The material level should be below all known obstructions at the moment when Auto False
Echo Suppression learns the echo profile. Ideally the vessel should be empty or almost
empty, and if an agitator is present, it should be running.
The device learns the echo profile over the whole measurement range and the TVT is
shaped around all echoes present at that moment.
Auto False Echo Suppression Range (2.8.7.2.)
Auto False Echo Suppression Range specifies the range within which the learned TVT is
applied. Default TVT is applied over the remainder of the range.
The learned TVT screens out the false echoes caused by obstructions. The default TVT
allows the material echo to rise above it.
Auto False Echo Suppression Range must be set to a distance shorter than the distance to
the material level when the environment was learned, to avoid the material echo being
screened out.
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SITRANS LR250 with mA/HART
Operating Instructions, 10/2019, A5E32220602-AG