# FIR Narrowband Filtering (G Dataflow)

Filters an input sequence using a specific interpolated FIR (IFIR) filter.

##### Programming Patterns

You can use the FIR Narrowband Filter Design node to generate the IFIR Filter for this node.

## signal

The input signal.

This input can be a 1D array of double-precision, floating-point numbers or a 1D array of complex double-precision, floating-point numbers.

## IFIR filter

The IFIR filter.

### filter type

Passband of the filter.

Name Description
Lowpass

Uses a lowpass filter.

Highpass

Uses a highpass filter.

Bandpass

Uses a bandpass filter.

Bandstop

Uses a bandstop filter.

Default: Lowpass

### interpolation

The interpolation factor M.

The model filter is stretched by interpolation times.

### Model Filter

The coefficients of the model filter.

### Image Suppressor

The coefficients of the filter image suppressor.

## error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

Filtered signal.

## error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

## Algorithm for Calculating the Delay for the Filter

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

$\mathrm{delay}=\frac{\left[\left({N}_{G}-1\right)M+{N}_{I}\right]}{2}$

where

• NG is the number of elements in Model Filter
• NI is the number of elements in Image Suppressor
• M is the value of interpolation

Where This Node Can Run:

Desktop OS: Windows

FPGA: This product does not support FPGA devices