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7 Menu
7.4.3.3 Filtering method
If rectangle is selected, signal filtering is performed precisely at
the marked point.
With Hanning, the range of the marked point is faded in with soft
transitions.
7.5
Measurement method
You can use the measurement method function to change be-
tween standard measurement (= correlation measurement) and
sound velocity measurement (see section 5).
7.6
Parameter
Use the parameter sub-menus to set parameters which are hav-
ing effect on the measurement.
7.6.1
Noise suppression
The noise suppression function can be used for reducing the neg
-
ative effect of temporary interferences (vehicles, pedestrians).
If the noise suppression function is enabled, it is assumed that
optimum results can be achieved in those moments in which the
measured noise (signal) is relatively low. This means that the per
-
manently present leakage noise is preponderantly undisturbed.
In moments in which the signal is relatively loud, the additional
noise must come from a interference source in all probability,
leading to much less reliable measurement results.
The level range is limited by the upper threshold and the lower
threshold. During a running
measurement, these thresholds for
signal 1 and 2 are indicated as horizontal lines on the left or right
edge of the display.
After a defined interval, the level range is automatically and slowly
increased, if the current level values lie permanently above the
level range. In the same way the level range is reduced, if the
current level values lie permanently below the level range.