Company Events Academic Community Support Solutions Products & Services Contact NI MyNI

FIR Windowed Filter VI

LabVIEW 2013 Help

Edition Date: June 2013

Part Number: 371361K-01

»View Product Info

Owning Palette: Filters VIs

Requires: Full Development System

Filters the input data sequence, X, using the set of windowed FIR filter coefficients specified by the sampling freq: fs, low cutoff freq: fl, high cutoff freq: fh, and number of taps. Wire data to the X input to determine the polymorphic instance to use or manually select the instance.

Details  Example

Use the pull-down menu to select an instance of this VI.

FIR Windowed Filter (DBL)

window parameter is the beta parameter for a Kaiser window, the standard deviation for a Gaussian window, and the ratio, s, of the main lobe to the side lobe for a Dolph-Chebyshev window. If window is any other window, this VI ignores this input.

The default value of window parameter is NaN, which sets beta to 0 for a Kaiser window, the standard deviation to 0.2 for a Gaussian window, and s to 60 for a Dolph-Chebyshev window.
filter type specifies the passband of the filter.

0Lowpass
1Highpass
2Bandpass
3Bandstop
X is the input signal to filter.
sampling freq: fs is the frequency in Hz at which you want to sample X 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 Filtered X to an empty array and returns an error.
low cutoff freq: fl is the low cutoff frequency in Hz and must observe the Nyquist criterion. The default is 0.125 Hz. If low cutoff freq : fl is less than zero or does not meet the Nyquist criterion, the VI sets Filtered X to an empty array 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.
taps determines the total number of FIR coefficients and must be greater than zero. The default is 25. If taps is less than or equal to 0, the VI sets Filtered X to an empty array and returns an error. taps must be odd for highpass and bandstop filters.
window specifies the type of smoothing window. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband.

0Rectangle (default)
1Hanning
2Hamming
3Blackman-Harris
4Exact Blackman
5Blackman
6Flat Top
74 Term B-Harris
87 Term B-Harris
9Low Sidelobe
11Blackman Nuttall
30Triangle
31Bartlett-Hanning
32Bohman
33Parzen
34Welch
60Kaiser
61Dolph-Chebyshev
62Gaussian
Filtered X is the output array of filtered samples. Filtered X has an associated index delay caused by the convolution operation. This VI calculates the delay using the following equation:

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.

FIR Windowed Filter (CDB)

window parameter is the beta parameter for a Kaiser window, the standard deviation for a Gaussian window, and the ratio, s, of the main lobe to the side lobe for a Dolph-Chebyshev window. If window is any other window, this VI ignores this input.

The default value of window parameter is NaN, which sets beta to 0 for a Kaiser window, the standard deviation to 0.2 for a Gaussian window, and s to 60 for a Dolph-Chebyshev window.
filter type specifies the passband of the filter.

0Lowpass
1Highpass
2Bandpass
3Bandstop
X is the input signal to filter.
sampling freq: fs is the frequency in Hz at which you want to sample X 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 Filtered X to an empty array and returns an error.
low cutoff freq: fl is the low cutoff frequency in Hz and must observe the Nyquist criterion. The default is 0.125 Hz. If low cutoff freq : fl is less than zero or does not meet the Nyquist criterion, the VI sets Filtered X to an empty array 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.
taps determines the total number of FIR coefficients and must be greater than zero. The default is 25. If taps is less than or equal to 0, the VI sets Filtered X to an empty array and returns an error. taps must be odd for highpass and bandstop filters.
window specifies the type of smoothing window. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband.

0Rectangle (default)
1Hanning
2Hamming
3Blackman-Harris
4Exact Blackman
5Blackman
6Flat Top
74 Term B-Harris
87 Term B-Harris
9Low Sidelobe
11Blackman Nuttall
30Triangle
31Bartlett-Hanning
32Bohman
33Parzen
34Welch
60Kaiser
61Dolph-Chebyshev
62Gaussian
Filtered X is the output array of filtered samples. Filtered X has an associated index delay caused by the convolution operation. The delay is given by the following equation.

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.

FIR Windowed Filter Details

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.

Example

Refer to the FIR Windowed Filter Design VI in the labview\examples\Signal Processing\Filters directory for an example of using the FIR Windowed Filter VI.


 

Your Feedback! poor Poor  |  Excellent excellent   Yes No
 Document Quality? 
 Answered Your Question? 
Add Comments 1 2 3 4 5 submit