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4 Functional principle – Ultrasonic-flow measurement
4.5 Batch mode
In general, the USM-GT-400 is set for an optimal operation without disturbance.
The setting / changing of the batch mode allows adaptation to disturbed condi-
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tions. The setting allows operation at "high-turbulent" flow conditions as well as at
"strong background noise" conditions. High turbulent means highly distorted veloc-
ity profiles and rapidly changing asymmetries. A "smallest" batch mode should be
chosen. At strong background noise, the signal detection can be disturbed, too. A
"longer" batch mode increases the signal stability significantly. The number of
batches permits a change of the signal duration.
• P1 Number of F-batches per measuring path 1
• ...
• P8 Number of F-batches per measuring path 8
The default values are 2. 0 and 1 are identical; there is no batch activated. All
larger values are squared; F-Batch 2 means there are 4 signals superimposed. If
the F-Batch is active the ring down time should be chosen as short as possible,
preferably to 0 ms. The slow batch mode can be activated in coordinate AI-09; it is
to be squared for all paths, too.
4.6 Signal damping
The output signal of the USM can be smoothed using the parameters E-9 (number
of GDs) and AK-34 to AP-24 (F-Batch). The choice of the settings for these
parameters is an optimization between interference immunity (high damping) and
short response time to changes in flow rate (low damping). As standard, the USMs
are delivered with GD=10 and F-Batch=2. This means:
a) The output signal is the moving average over the last 10 measurements. The
number of measured values included in the moving average is entered directly
in E-9.
b) The mean value of 4 raw signals is included in the measurements. The number
of these measurements (F-batch) is path-specific and equal to the square of
the input value in AK-34 to AP-34.
The shortest possible response time is therefore obtained with E-9 = 1 and AK-34
to AP-34 = 1. However, these settings should only be used with stable flow profiles
and low noise levels. If necessary, these parameters must be optimized during
commissioning.
Manual USM GT400 · EN10 · May 2021
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