Digital FIR Filter VI

Owning Palette: Waveform Conditioning VIs

Requires: Full Development System

Filters signals in either single or multiple waveforms. If you are filtering multiple waveforms, the VI maintains separate filter states for each waveform. The data types you wire to the signal in and FIR filter specifications inputs determine the polymorphic instance to use.

Note  Do not use the single-channel instance of this VI for continuous multiple-channel processing.

Details  Examples

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

Select an instance FIR Filter for 1 ChanFIR Filter for N ChanFIR Filter by N Specs for N ChanFIR Filter for 1 Chan (CDB)FIR Filter for N Chan (CDB)FIR Filter by N Specs for N Chan (CDB)

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FIR Filter for 1 Chan

	reset filter forces the filter coefficients to be redesigned and the internal filter states to be reset to zero when it is TRUE.
	signal in is the waveform to be filtered.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal out is the filtered waveform.
	filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

FIR Filter for N Chan

	reset filters forces the filter coefficients to be redesigned and the internal filter states to be reset to zero for each input waveform when it is TRUE.
	signal(s) in is an array of waveforms containing the signals to filter.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal(s) out is an array of signals that have been filtered according to the filter specifications controls.
	filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

FIR Filter by N Specs for N Chan

	reset filters forces the filter coefficients to be redesigned and the internal filter states to be reset to zero for each input waveform when it is TRUE.
	signal(s) in is an array of waveforms containing the signals to filter.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications is an array of filter specifications. This array must have the same size as the signal(s) in array of waveforms. FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is an array of optional filter specifications. This array may be empty or must have the same size as the FIR filter specifications array. optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal(s) out is an array of signals that have been filtered according to the filter specifications controls.
	filter information is an array of clusters containing information about each of the designed filters. filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

FIR Filter for 1 Chan (CDB)

	reset filter forces the filter coefficients to be redesigned and the internal filter states to be reset to zero when it is TRUE.
	signal in is the waveform to be filtered.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal out is the filtered waveform.
	filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

FIR Filter for N Chan (CDB)

	reset filters forces the filter coefficients to be redesigned and the internal filter states to be reset to zero for each input waveform when it is TRUE.
	signal(s) in is an array of waveforms containing the signals to filter.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal(s) out is an array of signals that have been filtered according to the filter specifications controls.
	filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

FIR Filter by N Specs for N Chan (CDB)

	reset filters forces the filter coefficients to be redesigned and the internal filter states to be reset to zero for each input waveform when it is TRUE.
	signal(s) in is an array of waveforms containing the signals to filter.
	error in describes error conditions that occur before this node runs. This input provides standard error in functionality.
	FIR filter specifications is an array of filter specifications. This array must have the same size as the signal(s) in array of waveforms. FIR filter specifications are the minimum values needed to specify the FIR filter. Topology determines the design type of the filter. 0 Off (default) 1 FIR by Specification 2 Equi-ripple FIR 3 Windowed FIR Type specifies the passband of the filter according to the following values. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop #Taps is the number of taps in the FIR filter. The default is 50. Lower PB is the lower of the two passband frequencies. The default is 100 Hz. Upper PB is the higher of the two passband frequencies. The default is 0. Lower SB is the lower of the two stopband frequencies. The default is 200 Hz. Upper SB is the higher of the two stopband frequencies. The default is 0.
	optional FIR filter specifications is an array of optional filter specifications. This array may be empty or must have the same size as the FIR filter specifications array. optional FIR filter specifications is a cluster of additional parameters that can be used when specifying an FIR filter. PB Gain is the gain at the passband frequencies. Gain may be specified in linear terms or dB. The default is –3dB. SB Gain is the gain at the stopband frequencies. Gain may be specified in linear terms or dB. The default is –60dB. Scale determines how the PB Gain and SB Gain parameters are interpreted. Window controls which smoothing window is applied to the truncated coefficients. Smoothing windows decrease ripple in the filter passband and improve the ability of the filter to attenuate frequency components in the filter stopband. 0 None 1 Hanning 2 Hamming 3 Triangular 4 Blackman 5 Exact Blackman 6 Blackman-Harris 7 Kaiser-Bessel 8 Flat Top
	signal(s) out is an array of signals that have been filtered according to the filter specifications controls.
	filter information is an array of clusters containing information about each of the designed filters. filter information contains the magnitude and phase responses of the filter in a cluster that is ready to graph. filter information also contains the order of the filter. magnitude H(w) is the magnitude response of the filter. You can wire this cluster to a graph. f0 is the start frequency of the magnitude response. df is the spacing between elements of the magnitude response in hertz. Mag H(w) is an array of values containing the magnitude response of the filter. phase H(w) is the phase response of the filter. f0 is the start frequency of the phase response. df is the spacing between elements of the magnitude response in hertz. Phase H(w) is an array of values containing the phase response of the filter, expressed in degrees. order is the order of the filter.
	error out contains error information. This output provides standard error out functionality.

Digital FIR Filter Details

This VI filters the signal(s) in a waveform array according to the FIR filter specifications and optional FIR filter specifications arrays. If you are filtering multiple waveforms, the VI applies a different filter to each of the input waveforms and maintains a separate filter state for each waveform. The VI uses the optional FIR filter specifications only if Filter topology is FIR by Specification or Windowed FIR. You do not need to wire reset filter. This VI resets itself the first time it is called.

The Digital FIR Filter VI can perform single-channel measurements in both one-shot mode (single call) and continuous mode (multiple calls with history). It can perform multi-channel measurements only in one-shot mode. If you want to make multiple-channel measurements in continuous mode, either use the multichannel instance of this VI or use one instance of this VI per channel.

The single-channel instance of this VI is intended primarily for continuous processing of a single channel. Do not generalize this behavior to the multi-channel case, typically by using this single-channel VI in a For Loop to continuously process multiple channels by indexing an array of waveforms.

The single-channel instance of this VI maintains internal state information for a single channel only. Calling this VI to process another channel without clearing the history using the reset filter control results in an unexpected behavior of this VI because the internal state information is passed from one channel to another.

Related Information

Passband Ripple and Stopband Attenuation

Examples

Refer to the following VIs for examples of using the Digital FIR Filter VI:

• FIR Filtering and Response VI: labview\examples\Signal Processing\Waveform Conditioning

   Open example  Find related examples

• FIR Filtering Using Optional Specs VI: labview\examples\Signal Processing\Waveform Conditioning

   Open example  Find related examples