FIR Narrowband Coefficients (Not in Base Package)

Generates a set of filter coefficients to implement a digital interpolated FIR filter. You can pass these coefficients to the FIR Narrowband Filter VI to filter the data. Details

ripple: rp is the ripple in the passband of the filter. The default is 0.01.
sampling freq: fs is the sampling frequency and must be greater than zero. The default is 1.0. If sampling freq: fs is less than or equal to zero, the VI sets the coefficients to an empty cluster and returns an error.
passband: fpass is the passband bandwidth. The default is 0.01.
stopband: fstop is the stopband bandwidth. The default is 0.02.
center freq: fc is the center frequency of the filter. The default is 0.1.
attenuation (db): Ar is the attenuation in the stopband of the filter. The default is 60 decibels.
filter type specifies the passband of the filter.

0Lowpass (default)
1Highpass
2Bandpass
3Bandstop
IFIR Coefficients is a cluster that contains IFIR coefficients.
filter type is the filter type that you use to determine how to filter the data.

0Lowpass
1Highpass
2Bandpass
3Bandstop
4Wideband-Lowpass (cutoff frequencies near Nyquist)
5Wideband-Highpass (cutoff frequencies near zero)
interpolation is the interpolation factor M. The model filter is stretched by interpolation times.
Model Filter contains the coefficients of the model filter.
Image Suppressor contains the coefficients of the filter image suppressor.
error returns any error or warning from the VI. Refer to Signal Processing Error Codes for more information about these conditions.

FIR Narrowband Coefficients Details

The overall filter is a linear-phase FIR filter. The delay for this filter is

,

where

is the number of elements in the array Model Filter.

is the number of elements in the array Image Suppressor.

M is the value of interpolation in the cluster IFIR Coefficients.

You can design narrowband FIR filters using the FIR Narrowband Coefficients VI, and then implement the filtering using the FIR Narrowband Filter VI. The design and implementation are separate operations because many narrowband filters require long design times, whereas the actual filtering is very fast and efficient. Keep this in mind when creating your narrowband filtering diagrams.