National Instruments 1142 用户手册
Chapter 4
Theory of Operation
© National Instruments Corporation
4-9
Figure 4-6. Phase Response Characteristics of the SCXI-1141/1142/1143
Module Filters
Figure 4-7 shows the advantages of the SCXI-1142 Bessel filter. The
Bessel filter is designed for constant group delay at the expense of passband
gain and stopband rolloff. As a result, the SCXI-1142 Bessel filter is the
best choice when the phase information of a signal is important or a signal
must maintain a constant delay regardless of its frequency components.
Bessel filter is designed for constant group delay at the expense of passband
gain and stopband rolloff. As a result, the SCXI-1142 Bessel filter is the
best choice when the phase information of a signal is important or a signal
must maintain a constant delay regardless of its frequency components.
0
0.5
1
1.5
2
–800
–600
–400
–200
0
Bessel (1142)
Butterworth (1143)
Elliptic (1141)
Frequency (Normalized)
Phase Shift (Deg
rees)