Bessel Filter (Not in Base Package)

Generates a digital Bessel filter by calling the Bessel Coefficients VI. Details  Example

	filter type specifies the passband of the filter. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop
	X is the input signal to filter.
	sampling freq: fs is the sampling frequency and must be greater than zero. The default is 1.0. If it is less than or equal to zero, the VI sets Filtered X to an empty array and returns an error.
	high cutoff freq: fh is the high cutoff frequency. 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 and must observe the Nyquist criterion. The default is 0.125. If low cutoff freq: fl is less than or equal to zero or greater than half the value of sampling freq: fs, the VI sets Filtered X to an empty array and returns an error. When filter type is 2 (Bandpass) or 3 (Bandstop), low cutoff freq: fl must be less than high cutoff freq: fh.
	order specifies the filter order and must be greater than zero. The default is 2. If order is less than or equal to zero, the VI sets Filtered X to an empty array and returns an error.
	init/cont controls the initialization of the internal states. The default is FALSE. When init/cont is FALSE, the internal states are initialized to zero. When init/cont is TRUE, the internal filter states are initialized to the final filter states from the previous call to this instance of this VI. To filter a large data sequence that has been split into smaller blocks, set this control to FALSE for the first block and to TRUE for continuous filtering of all remaining blocks.
	Filtered X is the output array of filtered samples.
	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.

Bessel Filter Details

After calling the Bessel Coefficients VI, the Bessel Filter VI calls the IIR Cascade Filter VI to obtain a Bessel Filtered X sequence.

The values for high cutoff freq: fh and low cutoff freq: fl must observe the following relationship.

0 < f₁ < f₂ <0.5f_s

where f₁ is low cutoff freq: fl, f₂ is high cutoff freq: fh, and f_s is sampling freq: fs.

Refer to the LabVIEW Analysis Concepts manual for more information about Bessel filters.

Example

Refer to the IIR Filter Design VI in the labview\examples\analysis\fltrxmpl.llb directory for an example of using the Bessel Filter VI.