App-31
IM 701210-06E
Appendix
App
GAUSS Filter
Characteristics
• Pass band is flat.
• The attenuation is –3 dB at the cutoff frequency.
Attenuation is equal to –3.0
×
(f/
fc
)
2
.
• Has linear phase characteristics and constant group delay.
• Only low-pass filter can be specified.
-80
-60
-40
-20
0
fc
-3 dB
-3.0 (f/f
c
)
2
dB
GAUSS Frequency Characteristics Example
0 f
0.1 f
0.2 f
0.3 f
0.4 f
0.5 f
dB
(f: sampling frequency [Hz])
Order Table
See below for the GAUSS filter orders.
GAUSS Filter Order
Cutoff frequency
2%
3%
4%
5%
6%
7%
8%
9%
Order
49
33
25
21
17
17
13
13
Cutoff frequency
10%
11%
12%
13%
14%
15%
16%
17%
Order
9
9
9
9
9
9
9
5
Cutoff frequency
18%
19%
20%
21%
22%
23%
24%
25%
Order
5
5
5
5
5
5
5
5
Cutoff frequency
26%
27%
28%
29%
30%
Order
5
5
5
5
5
Computation Delay
The group delay can be derived from the following equation. It is constant and depends
on the filter order.
Group delay = (Filter order – 1)/2
Unit: s/T
s
(where T
s
is the sampling frequency [s])
The computation delay can be derived from the following equation.
Computation delay = {4 + (filter order – 1)/2}
×
sampling period
However, if the sampling frequency exceeds 100 kHz, it is fixed to 100 kHz (10
µ
s).
It is also fixed to 100 kHz (10
µ
s) when in envelope mode.
Appendix 6 DSP Channel Computation (Optional)
