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User manual SCAIME:
NU-Soft-eNod4F-E-0716_235704-C.doc
12.2.4
Limitations
Recursive filters like
eNod4
low-pass filters are computed according to the filter order, the desired cut-off frequency
and the sampling rate. There are some limitations to respect in order to ensure a safe functioning of the signal
processing. They are listed in the table below:
A/D conversion rate
(meas/s)
min low-pass cut-off
frequency (Hz)
A/D conversion
rate (meas/s)
min low-pass cut-off
frequency (Hz)
50 Hz rejection
60 Hz rejection
2nd order
3rd order
2nd order
3rd order
6.25
0.10
0.10
7.5
0.10
0.10
12.5
0.10
0.10
15
0.10
0.15
25
0.10
0.15
30
0.15
0.20
50*
0.15
0.25
60*
0.20
0.30
100*
0.25
0.50
120*
0.30
0.60
200*
0.50
1.00
240*
0.60
1.20
400
1.00
2.00
480
1.20
2.40
800
2.00
4.00
960
2.40
4.80
1600
4.00
8.00
1920
4.80
9.60
(*) values of A/D conversion rate that are accessible in feeder mode.
12.2.5
Depth of moving average filter on weights
A moving average filter on weight can be set in cascade after previous filters. This filter is used to smooth the weight
value in case of random interferences. If enable, this filter computes the mean of a specified last number of measures
which are output of the previous filters. The number of measures is defined by
depth of moving average filter on
weights
parameter. A high filter depth will give a better stability, with a longer response time.
Filter depth admitted values: 0(disabled) up to 128.
12.2.6
Tolerance of clipping filter on instant flow rates
When eNod4 is used in loss in weight feeder, it's possible to operate a clipping filter on the successive values of flow
rate. Clipping range is defined in 0.1% of the nominal flow rate. This filter will substitute flow rate values outside the
clipping range by the meaning of precedent flow rate values. It allows to suppress short asynchronous physical
disturbances on weight measures due to the environment. The filter is disabled when parameter is cleared.
12.2.7
Average flow rate determination depth
This parameter specifies the depth of the moving average filter on successive instant flow rate values in order to
produce the average flow rate. The average flow rate is only produced for display and generally it is appropriate to set
average flow rate determination depth parameter to the maximal value 128. The filter is disabled when parameter is
cleared.
