National Instruments Car Stereo System 320571-01 用户手册

Generates the set of filter
coefficients to implement an
inverse IIR filter as specified
by the Chebyshev II Filter
mode.  You can then pass
these coefficients to the DSP
IIR Filter VI to filter a
sequence of data.

filter type specifies the passband of the filter.  filter type has four options:

0:  lowpass.
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.

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.

low cutoff freq: fl is the low cutoff frequency.  The VI ignores this parameter when filter type is
highpass.  low cutoff freq: fl defaults to 0.125.

Note: fh and fl must observe the Nyquist criterion:    0 

≤

 fl 

≤

 fh 

≤

 fs /2.

attenuation must be greater than 0.0.  If attenuation is less than or equal to zero, the VI returns an
error.  attenuation defaults to 60.0.

order must be greater than zero.  If the filter order is less than or equal to zero, the VI returns an error.
order defaults to 2.

Forward Coefficients in is a DSP Handle Cluster that indicates the memory buffer on the DSP board
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.

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.

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.