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5.2.4
DR3 - Type of low pass filters
3 types of filter are available to choose from, for suppressing interference
(critically damped, Bessel filter, Butterworth filter). The selection is performed
empirically. The following figures show the step responses of the three filters
(fg = 2 Hz).
Image 5-3
Digital low pass filter step response
5.2.5
DR3 - Limit frequency
Defining the limit frequency is very important for suppressing interference. The
"speed" of the scale's reaction to the change in measurement value is set by
defining the limit frequency.
A value of e.g. 2 Hz leads to a relatively quick scale reaction to a weight change,
a value of e.g. 0.5 Hz makes the scale "sluggish".
5.2.6
DR3 - Type of average value filters
The average value filter is used to calm the weighing value compensating for
random interference. The weight value is constructed from the average value of the
SIWAREX FTA
Weighing Functions
5-49
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