Bessel Filter (Not in Base Package)

Generates a digital, Bessel filter using filter type, sampling frequency: fs, high cutoff frequency: fh, low cutoff frequency: fl, and order by calling the Bessel Coefficients VI. Details

filter type specifies the passband of the filter.

0Lowpass
1Highpass
2Bandpass
3Bandstop
X is the input signal to be filtered.
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.
low cutoff freq: fl is the low cutoff frequency and must observe the Nyquist criterion. The default is 0.125.

where is the cutoff frequency, and is the sampling frequency. If low cutoff freq : fl is less than zero or greater than half the sampling frequency, 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.

Note  All cutoff frequencies must be less than half .
order 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. When init/cont is FALSE (default), 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. Refer to Signal Processing Error Codes for more information about these conditions.

Bessel Filter Details

After calling the Bessel Coefficients VI, the Bessel Filter VI then calls the IIR Cascade Filter VI to filter the X sequence using this model to obtain a Bessel Filtered X sequence.