Last Modified: August 6, 2018

Designs and implements an IIR filter whose magnitude-squared response is inversely proportional to frequency over a specified frequency range. You can use the inverse-f filter to colorize spectrally flat or white noise.

Exponent of the desired inverse-f spectral shape. This node designs a digital filter with the desired magnitude-squared response of 1/frequency^{exponent}.

**Default: **1

A Boolean that specifies the initialization of the internal state of the node.

True | Initializes the internal state to zero. |

False | Initializes the internal state to the final state from the previous call of this node. |

This node automatically initializes the internal state to zero on the first call and runs continuously until this input is True.

**Default: **False

Lower frequency edge of the operating frequency range of the filter.

**Default: **0.1

Higher frequency edge of the operating frequency range of the filter.

**Default: **100

Number of first order stages of the inverse-f filter.

Increasing **order** improves the inverse-f spectral shape but requires more computation time during the filter operation.

**Default: **5

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 design sample rate in samples/second.

**Default: **1000

Frequency, in radians per second, at which the ideal inverse-f filter response has unity gain.

The actual inverse-f filter is designed to approximate the ideal filter over the frequency range defined by **low cutoff frequency**, **high cutoff frequency**, and **order**. Therefore, the actual gain of the filter at **unity gain frequency** is near unity only if **unity gain frequency** is within the design frequency range specified in **low cutoff frequency**, **high cutoff frequency**, and **order**.

**Default: **1

Magnitude and phase of the frequency response of the designed inverse-f filter.

Magnitude of the frequency response of the designed inverse-f filter in dB.

Frequencies of the frequency response of the designed inverse-f filter in Hz.

Magnitudes of the frequency response of the designed inverse-f filter in dB.

Phase of the frequency response of the designed inverse-f filter in degrees.

Frequencies of the frequency response of the designed inverse-f filter in Hz.

Phases of the frequency response of the designed inverse-f filter in degrees.

Magnitude of the deviation of the actual inverse-f filter, in decibels, when measured against the ideal inverse-f filter.

The ideal filter has a magnitude-squared response proportional to 1/f ^{exponent} over the frequency range specified by **low cutoff frequency**, **high cutoff frequency**, and **order**.

Frequencies of the magnitude error in Hz.

Magnitudes of the magnitude error in dB.

Expected noise bandwidth of the designed inverse-f filter.

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: Not supported

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