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
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