Inverse f Noise Waveform VI
- Updated2025-07-30
- 5 minute(s) read
Generates a continuous noise waveform with a power spectral density that is inversely proportional to frequency over a specified frequency range.

Inputs/Outputs
reset signal (F)
—
reset signal resets the noise sample generator and the time stamp to zero. The default is FALSE.
noise density
—
noise density specifies the spectral density (V/root Hz) of the ideal inverse-f noise waveform at the frequency reference freq. The actual inverse-f noise waveform approximates the ideal inverse-f noise over the frequency range defined by filter specifications. Therefore, the actual spectral density of the inverse-f noise waveform at reference freq is near noise density only if reference freq is within the design frequency range specified in filter specifications.
exponent
—
exponent specifies the exponent of the desired inverse-f noise spectral shape. This VI generates the inverse-f noise waveform by passing white noise through a digital filter with a desired magnitude-squared response of 1/frequency^exponent.
filter specifications
—
filter specifications specifies the operating frequency range and the filter order of the filter.
seed
—
seed, when greater than 0, causes reseeding of the noise sample generator. The default is –1. LabVIEW maintains the internal seed state independently for each instance of this reentrant VI. For a specific instance of this VI, if seed is less than or equal to 0, LabVIEW does not reseed the noise generator, and the noise generator resumes producing noise samples as a continuation of the previous noise sequence.
error in (no error)
—
error in describes error conditions that occur before this node runs. With the following exception, this input provides standard error in functionality. This node runs normally even if an error occurred before this node runs.
sampling info
—
sampling info contains sampling information.
reference freq (Hz)
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reference freq specifies the frequency in Hz at which the spectral density of the ideal inverse-f noise waveform is equal to noise density. The actual inverse-f noise waveform source is designed to approximate the ideal inverse-f noise waveform over the frequency range defined in filter specifications. Therefore, the actual spectral density of the inverse-f noise waveform at reference freq is near noise density if reference freq is within the design frequency range specified in filter specifications.
signal out
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signal out returns the generated inverse-f noise waveform.
magnitude error (dB)
—
magnitude error returns the magnitude of the deviation of the actual inverse-f filter in dB 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 filter specifications.
expected rms
—
expected rms returns the expected RMS level of the generated noise waveform.
filter information
—
filter information returns the magnitude and phase of the frequency response of the designed inverse-f filter.
error out
—
error out contains error information. This output provides standard error out functionality. |
This VI generates the inverse-f noise waveform by passing spectrally flat, or white, noise through a digital filter with a desired magnitude-squared response of 1/frequency^exponent.
reset signal (F)
—
noise density
—
filter specifications
—
order
—
error in (no error)
—
signal out
—
magnitude error (dB)
—
frequency (Hz)
—
expected rms
—
error out
—