Mitsubishi Electric MELSEC iQ-R User Manual page 34

Characteristics and advantages of the digital filters
The following table lists the characteristics and advantages of the digital filters.
Filter type
Low pass filter
(low frequency pass
filter)
High pass filter
(high frequency pass
filter)
Band pass filter
(band frequency pass
filter)
G: Attenuation rate (dB)
f: Frequency (Hz)
*2
: Pass band
: Attenuation band
*4
: Stopband
*1 Indicates the reciprocal number of the conversion cycle (1/conversion cycle).
*2 Indicates the frequency band where noise passes through the filter without being attenuated.
*3 Indicates the frequency band whose attenuation rate of the filter is in a transition state.
*4 Indicates the frequency band where noise is attenuated by the filter.
1 FUNCTIONS
32
1.5 A/D Conversion Method
Characteristic
G(dB)
0
-53
0 (2)
G(dB)
0
-53
0 (4)
G(dB)
0
(1)
-53
0 (5) (6)
(1) Attenuation band width
(2) Pass band edge frequency
(3) Pass band edge frequency + Attenuation band width
*3
(4) Pass band edge frequency - Attenuation band width
(5) Pass band edge frequency (Low) - Attenuation band width
(6) Pass band edge frequency (Low)
(7) Pass band edge frequency (High)
(8) Pass band edge frequency (High) + Attenuation band width
Advantage
• Analog input values are processed every conversion cycle.
• This filter attenuates frequency signals between a pass band edge
frequency and the pass band edge frequency + an attenuation band
width to cut off frequency signals higher than the attenuation band.
• The target frequency of the filtering should be the same as, or lower
than 1/2 of the sampling frequency
(1)
(3) f(Hz)
• Analog input values are processed every conversion cycle.
• This filter attenuates frequency signals between a pass band edge
frequency and the pass band edge frequency - an attenuation band
width, cutting off frequency signals lower than the attenuation band.
• The target frequency of the filtering should be the same as, or lower
than 1/2 of the sampling frequency
(1)
(2) f(Hz)
• Analog input values are processed every conversion cycle.
• Both the low pass filter and high pass filter are set simultaneously. As
a result, only frequency within a specified bandwidth passes this
filter.
• The target frequency of the filtering should be the same as, or lower
than 1/2 of the sampling frequency
(1)
(7) (8) f(Hz)
*1
.
*1
.
*1
.