National Instruments 320571-01 用户手册
Chapter 2
NI-DSP Analysis VI Reference
NI-DSP SRM for LabVIEW for Windows
2-21
Part 3: NI-DSP Function Reference
DSP Elliptic Coefficients
Generates the set of filter
coefficients to implement a
digital elliptic IIR filter. You
can then pass these
coefficients to the DSP IIR
Filter VI.
coefficients to implement a
digital elliptic IIR filter. You
can then pass these
coefficients to the DSP IIR
Filter VI.
filter type specifies the passband of the filter. filter type has four options:
0: lowpass.
1: highpass.
2: bandpass.
3: bandstop.
1: highpass.
2: bandpass.
3: bandstop.
filter type defaults to lowpass.
sampling freq : fs is the sampling frequency and must be greater than 0. If it is less than or equal to
zero, the VI returns an error. sampling freq : fs defaults to 1.0.
zero, the VI returns an error. sampling freq : fs defaults to 1.0.
high cutoff freq: fh is the high cutoff frequency. The VI ignores this parameter when filter type is
lowpass. high cutoff freq: fh defaults to 0.45.
lowpass. high cutoff freq: fh defaults to 0.45.
low cutoff freq: fl is the low cutoff frequency. The VI ignores this parameter when filter type is
highpass. high cutoff freq: fh defaults to 0.125.
highpass. high cutoff freq: fh defaults to 0.125.
Note:
fh and fl must observe the Nyquist criterion: 0
≤
fl
≤
fh
≤
fs /2.
passband ripple must be greater than 0, and you must express it in decibels. If passband ripple is less
than or equal to zero, the VI returns an error. passband ripple defaults to 1.0.
than or equal to zero, the VI returns an error. passband ripple defaults to 1.0.
order must be greater than zero. If order is less than or equal to zero, the VI returns an error. order
defaults to 2.
defaults to 2.
stopband attenuation must be greater than 0, and you must express it in decibels. If stopband
attenuation is less than or equal to zero, the VI returns an error. stopband attenuation defaults to 60.0.
attenuation is less than or equal to zero, the VI returns an error. stopband attenuation defaults to 60.0.
Forward Coefficients in is a DSP Handle Cluster that indicates the memory buffer on the DSP board
that will contain the forward coefficients.
that will contain the forward coefficients.
Feedback Coefficients in is a DSP Handle Cluster that indicates the memory buffer on the DSP board
that will contain the feedback coefficients.
that will contain the feedback coefficients.
Forward Coefficients out is a DSP Handle Cluster that is identical to Forward Coefficients in, but
with the forward coefficients already stored in the memory buffer on the DSP board.
with the forward coefficients already stored in the memory buffer on the DSP board.
Feedback Coefficients out is a DSP Handle Cluster that is identical to Feedback Coefficients in, but
with the feedback coefficients already stored in the memory buffer on the DSP board.
with the feedback coefficients already stored in the memory buffer on the DSP board.