Owning Palette: Advanced IIR Filtering VIs
Requires: Full Development System
Generates the set of filter coefficients to implement an IIR filter as specified by the Bessel filter model.
You then can pass these coefficients to the IIR Cascade Filter VI.
|filter structure option specifies the order of the IIR cascade filter in IIR Filter Cluster.
|filter type specifies the passband of the filter.
|sampling freq: fs is the sampling frequency in Hz and must be greater than zero. The default is 1.0 Hz. If sampling freq: fs is less than or equal to zero, the VI sets Reverse Coefficients and Forward Coefficients to empty arrays and returns an error.|
|high cutoff freq: fh is the high cutoff frequency in Hz. The default is 0.45 Hz. The VI ignores this parameter when filter type is 0 (Lowpass) or 1 (Highpass). When filter type is 2 (Bandpass) or 3 (Bandstop), high cutoff freq: fh must be greater than low cutoff freq: fl and observe the Nyquist criterion.|
|low cutoff freq: fl is the low cutoff frequency in Hz and must observe the Nyquist criterion. The default is 0.125 Hz. When filter type is 2 (Bandpass) or 3 (Bandstop), low cutoff freq: fl must be less than high cutoff freq: fh.|
|order is the order of the IIR filter and must be greater than zero.|
|IIR Filter Cluster contains the cascaded form of IIR filter coefficients.
|error returns any error or warning from the VI. You can wire error to the Error Cluster From Error Code VI to convert the error code or warning into an error cluster.|
The values for low cutoff freq: fl and high cutoff freq: fh must observe the following relationship.
0 < f1 < f2 < 0.5fs
where f1 is low cutoff freq: fl, f2 is high cutoff freq: fh, and fs is sampling freq: fs. If you violate any of these conditions, this VI sets Reverse Coefficients and Forward Coefficients to empty arrays and returns an error.
The Bessel Coefficients VI is a subVI of the Bessel Filter VI.
Refer to the Online Filtering VI in the labview\examples\Signal Processing\Filters directory for an example of using the Bessel Coefficients VI.