Siemens Sitrans LR250 Instruction Manual page 63

2.2.4.5. Noise
2.2.4.5.1. Confidence
Measures echo reliability. It displays the echo confidence of the
measurement echo from the last shot. Echo Threshold defines the
minimum criterion for echo confidence. Confidence in the echo must be
larger than Echo Threshold for the device to select that echo.
Open the menu View – Echo Profile.
2.2.4.5.2. Strength
Displays the absolute strength (in dB referred to 1 µV rms) of the echo
selected as the measurement echo.
Open the menu View – Echo Profile.
2.2.4.5.3. Noise Average
Displays the average ambient noise (in dB referred to 1 µV rms) of a noise
profile. Noise level is a combination of transient noise and receiving
circuitry. After a measurement, the values from the previous noise shot
will be displayed.
2.2.5. TVT (Auto False Echo Suppression) setup
First SITRANS LR250 learns the echo profile. Then the learned profile, or part
of the learned profile, is used to screen out false echoes. See Before Auto
False Echo Suppression on page 69 and After Auto False Echo Suppression on
page 69 for examples.
2.2.5.1. TVT Hover Level
Defines how high the TVT (Time Varying Threshold) curve 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. When
SITRANS LR250 is located in the center of the vessel, the TVT hover level
may be lowered to increase the confidence level of the largest echo.
illustration of the TVT curve see
page 69
Values
7ML19985JE01
Values (view only)
Related Parameters
Values (view only)
.)
SITRANS LR250 (HART) – INSTRUCTION MANUAL
0 to 99
----
2.2.4.1.3. Echo Threshold
–20 to 99
Before Auto False Echo Suppression on
Range: 0 to 100%
Default: 40%
Shot not used
(For an
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