App-3
IM DL850E-01EN
Appendix 2 User-Defined Computation (Optional)
Digital Filter
Type
Type
Bandwidth
Gauss (Gaussian)
LowPass
Sharp
LowPass/HighPass/BandPass
IIR (Butterworth)
LowPass/HighPass/BandPass
Filter Order
See the following table for the filter orders.
2%
5%
10%
20%
30% (Cutoff)
Gauss
LowPass
49
21
9
5
5
Sharp
LowPass
88
36
18
9
8
HighPass
159
65
33
17
13
IIR
LowPass
4
4
4
3
2
HighPass
4
4
4
4
3
Filter Characteristics
Filter
Pass-band
Ripple
Attenuation Slope
Attenuation at
the Stop-band
Phase
Gauss
0 dB
*
−
Linear phase
Sharp
±0.3 dB
−40 dB at 1 oct (Lowpass),
−40 dB
Linear phase
−40 dB at −1 oct (Highpass)
−
Linear phase
IIR
0 dB
−5 dB at 1/6 oct (Lowpass),
−
Non-linear
phase
−20 dB at −1 oct (Highpass)
−
* For Gaussian filter: −3.0 × (f/fc)
2
dB (f: frequency, fc: cutoff frequency)
Frequency Characteristics of Filters
f: Sampling frequency (Hz)
Gauss (10% cutoff)
Sharp (Low pass; 10% cutoff)
IIR (Low pass; 10% cutoff)
The higher the filter order the longer it takes for computation.
Appendix