Siemens SITRANS LR250 Operating Instructions Manual page 154

Echo Threshold (2.5.7.3.)
Confidence (2.5.9.1.) describes the quality of an echo. Higher values represent higher
quality. Echo Threshold defines the minimum confidence value required for an echo to be
accepted as valid and evaluated.
Echo Lock (2.5.8.1.)
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:
Lock Off
SITRANS LR 250 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.
Auto False Echo Suppression (2.5.10.1.)
Notes:
• For detailed instructions on using this feature via AMS see
threshold)
on page 56.
• For detailed instructions on using this feature via the handheld programmer see
Auto False Echo Suppression (2.5.10.1.) on page 110.
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 (2.5.10.2.)
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.
Page 148 SITRANS LR250 (FF) – OPERATING INSTRUCTIONS
TVT (time varying
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