Last Modified: August 6, 2018

Designs 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.

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

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

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

Output IIR cascade filter.

Structure of the output filter.

The forward coefficients of the IIR cascade filter.

The reverse coefficients of the IIR cascade filter.

The sampling frequency in Hz.

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