Siemens Sitrans LR250 Operating Instructions Manual page 88

2.5.10.3. Hover Level
Defines how high the TVT (Time Varying Threshold) is placed above the
noise floor of the echo profile, as a percentage of the difference between
the peak of the largest echo in the profile and the noise floor. See Before
Auto False Echo Suppression on page 80 for an illustration.
Values
When the device is located in the center of the vessel, the TVT hover level
may be lowered to increase the confidence level of the largest echo.
2.5.10.4. Shaper Mode
Enables/disables TVT shaper (2.5.11.).
Options
2.5.11. TVT shaper
Note:
• The range is –100 to 100 bits. With 2 bits per dB this gives a range of –50 to
50 dB.
• Shaper Mode (2.5.10.4.) must be turned ON in order for TVT shaper points
to be transferred
Adjusts the TVT (Time Varying Threshold) at a specified range (breakpoint on
the TVT). This allows you to reshape the TVT curve to avoid unwanted echoes.
There are 40 breakpoints arranged in 5 groups. (We recommend using SIMATIC
PDM to access this feature.)
To use TVT shaper via SIMATIC PDM:
a) Go to Level Meter > Setup > Signal Processing > TVT setup > Shaper
Mode and select On.
b) Open the menu Device – Echo Profile Utilities and click on TVT Shaper. For
more detail see
To use TVT shaper via LUI (local user interface):
a) Go to Shaper Mode (2.5.10.4.) and select option ON.
b) In TVT shaper, go to Breakpoint 1-9 (2.5.11.1.).
c) Open Breakpoint 1 and enter the TVT Offset value (between –50 and 50).
d) Go to the next Breakpoint and repeat step (c) till all desired breakpoint
values have been entered.
1)
For an illustration, see
Echo Suppression
Page 82 SITRANS LR250 (PROFIBUS PA) – OPERATING INSTRUCTIONS
1)
* OFF
ON
TVT Shaper
on page 51.
Before Auto False Echo Suppression
on page 81.
Range: 0 to 100%
Default: 40%
and
)
After Auto False
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