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FIR Windowed Filter PtByPt (Not in Base Package)

LabVIEW 8.5 Help
August 2007

NI Part Number:
371361D-01

»View Product Info

Filters x using an FIR filter model.

This VI is similar to the FIR Windowed Filter VI.

Details  

initialize, when TRUE, initializes the internal state of the VI.
high cutoff freq: fh is the high cutoff frequency. The default is 0.45. 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.
filter type specifies the passband of the filter.

0Lowpass
1Highpass
2Bandpass
3Bandstop
x is the input signal to filter.
sampling freq: fs is the sampling frequency and must be greater than 0. The default is 1.0. If sampling freq: fs is less than or equal to 0, this VI sets Filtered x to 0 and returns an error.
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.

0None
1Hanning
2Hamming
3Triangular
4Blackman
5Exact Blackman
6Blackman-Harris
7Kaiser-Bessel
8Flat Top
taps determines the total number of FIR coefficients and must be greater than 0. The default is 25. If taps is less than or equal to 0, the VI sets Filtered x to 0 and returns an error. taps must be odd for highpass and bandstop filters.
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 0 or greater than half the value of sampling freq: fs, the VI sets Filtered x to 0 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.
Filtered x contains the result of filtering the input sequence x by convolution.
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 PtByPt 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.


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