FIR Narrowband Filter VI

Owning Palette: Advanced FIR Filtering VIs

Requires: Full Development System

Filters the input sequence X using the interpolated FIR (IFIR) filter specified by IFIR Coefficients.

Details  

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Select an instance FIR Narrowband Filter (DBL)FIR Narrowband Filter (CDB)

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FIR Narrowband Filter (DBL)

	X is the input signal to filter.
	IFIR Coefficients is a cluster that contains IFIR filter coefficients. You can use the FIR Narrowband Coefficients VI to generate the IFIR Coefficients to use. filter type is the filter type that you use to determine how to filter the data. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop 4 Wideband-Lowpass (cutoff frequencies near Nyquist) 5 Wideband-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.
	Filtered X is the output array of filtered samples.
	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 Narrowband Filter (CDB)

	X is the input signal to filter.
	IFIR Coefficients is a cluster that contains IFIR filter coefficients. You can use the FIR Narrowband Coefficients VI to generate the IFIR Coefficients to use. filter type is the filter type that you use to determine how to filter the data. 0 Lowpass 1 Highpass 2 Bandpass 3 Bandstop 4 Wideband-Lowpass (cutoff frequencies near Nyquist) 5 Wideband-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.
	Filtered X is the output array of filtered samples.
	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 Narrowband Filter Details

The overall filter is a linear-phase FIR filter. This VI calculates the delay for the filter using the following equation:

where N_G is the number of elements in the array Model Filter, N_I is the number of elements in the array Image Suppressor, and M is the value of interpolation.

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.