Version:

Last Modified: January 12, 2018

Designs a digital interpolated FIR (IFIR) filter.

You can design narrowband FIR filters using the FIR Narrowband Filter Design node, and then implement the filtering using the FIR Narrowband Filtering node. The design and implementation are separate operations, because many narrowband filters require long design times, whereas the actual filtering is fast and efficient.

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

The stopband bandwidth.

The value for this input must be greater than 0 and less than half of **sampling frequency**.

**Default: **0.02

The center frequency of the filter.

The value for this input must be greater than 0 and less than half of **sampling frequency**.

**Default: **0.2

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.

**Default: **No error

The sampling frequency in Hz. If **sampling frequency** is less than or equal to zero, this node returns an empty cluster for **IFIR filter** as well as an error.

**Default: **1.0

The ripple in the passband of the filter.

The value of this input must be greater than 0.

**Default: **0.01

The attenuation in the stopband of the filter.

The value of this input must be greater than 0.

**Default: **60 decibels

The IFIR filter.

Filter type of the IFIR filter.

Name | Description |
---|---|

Lowpass | The IFIR filter is a lowpass filter. |

Highpass | The IFIR filter is a highpass filter. |

Bandpass | The IFIR filter is a bandpass filter. |

Bandstop | The IFIR filter is a bandstop filter. |

Wideband-Lowpass | The IFIR filter is a wideband-lowpass filter with cutoff frequencies near Nyquist. |

Wideband-Highpass | The IFIR filter is a wideband-highpass filter with cutoff frequencies near zero. |

The interpolation factor M.

The model filter in this is stretched by **interpolation** times.

The coefficients of the model filter.

The coefficients of the filter image suppressor.

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

**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.

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

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

where

*N*_{G}is the number of elements in**Model Filter***N*_{I}is the number of elements in**Image Suppressor***M*is the value of**interpolation**

**Where This Node Can Run: **

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application