Last Modified: March 15, 2017

Designs a windowed FIR filter.

To filter a sequence of data, wire the **filter** output to the Filtering node.

A value that affects the output coefficients when **window type** is Kaiser, Gaussian, or Dolph-Chebyshev.

If **window type** is any other type of window, this node ignores this input.

This input represents the following information for each type of window:

**Kaiser**—Beta parameter**Gaussian**—Standard deviation**Dolph-Chebyshev**—The ratio,*s*, of the main lobe to the side lobe

**Default: **NaN—Causes this node to set beta to 0 for a Kaiser window, the standard deviation to 0.2 for a Gaussian window, and *s* to 60 for a Dolph-Chebyshev window

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.

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

Rectangle | 0 | Specifies a rectangle window. |

Hanning | 1 | Specifies a Hanning window. |

Hamming | 2 | Specifies a Hamming window. |

Blackman-Harris | 3 | Specifies a Blackman-Harris window. |

Exact Blackman | 4 | Specifies an Exact Blackman window. |

Blackman | 5 | Specifies a Blackman window. |

Flat Top | 6 | Specifies a Flat Top window. |

4 Term B-Harris | 7 | Specifies a 4 Term B-Harris window. |

7 Term B-Harris | 8 | Specifies a 7 Term B-Harris window. |

Low Sidelobe | 9 | Specifies a Low Sidelobe window. |

Blackman Nuttall | 11 | Specifies a Blackman Nuttall window. |

Triangle | 30 | Specifies a Triangle window. |

Bartlett-Hanning | 31 | Specifies a Bartlett-Hanning window. |

Bohman | 32 | Specifies a Bohman window. |

Parzen | 33 | Specifies a Parzen window. |

Welch | 34 | Specifies a Welch window. |

Kaiser | 60 | Specifies a Kaiser window. |

Dolph-Chebyshev | 61 | Specifies a Dolph-Chebyshev window. |

Gaussian | 62 | Specifies a Gaussian window. |

**Default: **0—Rectangle

An enum value that determines whether to scale the FIR windowed coefficients.

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

not scaled | Does not scale the FIR windowed coefficients. |

scaled | Scales the FIR windowed coefficients. |

**Default: **not scaled

The 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 low cutoff frequency in Hz. If this input is less than or equal to zero or does not meet the Nyquist criterion, the node returns an empty array as well as an error.

**Default: **0.125

The high cutoff frequency, in Hz. This value must observe the Nyquist criterion.

The node places the following restrictions on this parameter according to **filter type**:

filter type |
Restrictions |
---|---|

Lowpass or Highpass | The node ignores this input. |

Bandpass or Bandstop | This value must be greater than low cutoff frequency and less than half of sampling frequency. |

**Default: **0.45

The total number of FIR coefficients.

If **number of taps** is less than or equal to 0, the node returns an empty array as well as an error.

If **filter type** is 1 (Highpass) or 3(Bandstop), this input must be odd.

**Default: **25

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 this input is less than or equal to 0, the node returns an empty array as well as an error.

**Default: **1.0 Hz

Output FIR filter.

Structure of the output filter.

This output always returns FIR.

Coefficients of the FIR filter.

This output always returns an empty array because FIR filters do not have reverse coefficients.

The sampling frequency in Hz.

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.

**Where This Node Can Run: **

Desktop OS: Windows

FPGA: This product does not support FPGA devices