App-43
IM 701210-06E
Appendix
App
MEAN (Moving Average) Filter
Characteristics
• Pass band is flat.
• Has linear phase characteristics and constant group delay.
• The characteristics are of low-pass filters.
• Has comb-shaped bandwidth characteristics.
-80
-60
-40
-20
0
0 f
0.1 f
0.2 f
0.3 f
0.4 f
0.5 f
2
4
8
16
32
64
128
MEAN (Moving Average) Frequency Characteristics
dB
(f: sampling frequency [Hz])
Computation Delay
The group delay can be derived from the following equation. It is constant and depends
on the filter order.
Group delay = (Number of moving average points – 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 + (Number of moving average points – 1)/2}
×
sampling clock
cycle
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)
