National Instruments 1142 用户手册
Chapter 4
Theory of Operation
4-10
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Figure 4-7. Phase Error of the SCXI-1141/1142/1143 Module
The most common effect of phase nonlinearity is ringing in response to a
step input. As Figure 4-8 shows, the SCXI-1141 elliptic filter exhibits the
most overshoot and ringing and the SCXI-1142 Bessel filter has no
overshoot or ringing. The SCXI-1143 module Butterworth filter has a step
response that is a compromise between the SCXI-1141 module and the
SCXI-1142 module. The SCXI-1143 module filter has an overshoot, but it
has less ringing than the SCXI-1141. You should consider the step response
if the intended application is sensitive to overshoot or ringing. See
Table A-1,
step input. As Figure 4-8 shows, the SCXI-1141 elliptic filter exhibits the
most overshoot and ringing and the SCXI-1142 Bessel filter has no
overshoot or ringing. The SCXI-1143 module Butterworth filter has a step
response that is a compromise between the SCXI-1141 module and the
SCXI-1142 module. The SCXI-1143 module filter has an overshoot, but it
has less ringing than the SCXI-1141. You should consider the step response
if the intended application is sensitive to overshoot or ringing. See
Table A-1,
, for detailed
settling specifications. Additionally, use care when selecting gain settings
to assure that the input signal plus any overshoot voltage result in an output
signal within the ±5 V range of the SCXI-1141/1142/1143 module.
to assure that the input signal plus any overshoot voltage result in an output
signal within the ±5 V range of the SCXI-1141/1142/1143 module.
0
0.5
1
1.5
2
–100
0
100
200
300
Bessel (1142)
Butterworth (1143)
Elliptic (1141)
Frequency (Normalized)
Phase Error (Deg
rees)