
40 / 75
ba_aed104_8_e.doc
ASF
Amplifier Signal Filter
(Digital filter setting)
Range:
0...8
Factory setting:
5
Response time:
<15ms
Parameters:
1
Password protection:
none
Parameter protect.:
with command
TDD1
Input:
ASF(0...8);
Query:
ASF?;
Effect:
Entry of the filter stage as decimal number from
(0...8)
The AED has a multi-stage filter chain:
•
An analog 3rd order filter (cut-off frequency approx. 50 Hz)
•
Averaging over 2 measured values (at 200 Hz scan rate, fixed setting)
•
Standard filter (FMD0) or a FIR filter (FMD=1); cut-off frequency selectable through ASF, fixed scan rate =
100 Hz
•
Averaging for output rate reduction (selectable through ICR, scan rate <=100 Hz)
Thus the wanted filter effect and output rate can be set through the two commands (ASF, ICR). Further new
efficient digital filters have been implemented apart from the standard filter properties. The command FMD is
used for switching over between the two filter modes:
FMD 0;
Standard filter
FMD 1;
FIR filter (with fast settling time)
Filter characteristics of standard filters (FMD0):
ASF
Settling time
in ms to 0.1%
Cut-off frequency [Hz]
at –3dB
max. attenuation [dB]
at 300Hz
1
130
8
-20
2
320
3,5
-34
3
700
1,5
-48
4
1400
0,7
-60
5
2900
0,3
-72
6
5800
0,2
-82
7
11800
0,1
-90
8
23800
0,05
-96
The filter is switched off at
ASF0
. The cut-off frequency of the filter determines the settling time. The higher the
filter index, the better is the filter effect but the longer is the settling time on changing the weight. The filter
setting should be chosen as small as possible, whereby the measured value quiescence (standstill) must be
guaranteed at unchanging weight.