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    Designs an IIR filter whose magnitude-squared response is inversely proportional to frequency over a specified frequency range. This inverse-f filter is typically used to colorize spectrally flat, or white, noise.

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    exponent

    Exponent of the desired inverse-f spectral shape. This node designs a digital filter with the desired magnitude-squared response of 1/frequencyexponent.

    Default: 1

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    fs

    The design sample rate in samples/second.

    Default: 1000 samples/second

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    filter specifications

    Operating frequency range and the filter order of the filter.

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    lower cutoff freq

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

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    higher cutoff freq

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

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    order

    Number of first order stages of the inverse-f filter. Increasing order improves the inverse-f spectral shape but requires more computation time during filter operation.

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    unity gain frequency

    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 filter specifications. 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 filter specifications.

    Default: 1

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    noise bandwidth

    Expected noise bandwidth of the designed inverse-f filter.

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    IIR filter cluster

    The cascaded form of IIR filter coefficients.

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    filter structure

    Either IIR second-order or IIR fourth-order filter stages.

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    reverse coefficients

    The reverse coefficients of the IIR cascade filter.

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    Forward Coefficients

    The forward coefficients of the IIR cascade filter.

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    filter information

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

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    magnitude (dB)

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

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    frequency (Hz)

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

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    magnitude (dB)

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

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    phase (deg)

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

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    frequency (Hz)

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

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    phase (deg)

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

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    magnitude error

    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 filter specifications.

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    frequency (Hz)

    Frequencies of the magnitude error in Hz.

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    magnitude (dB)

    Magnitudes of the magnitude error in dB.

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    error

    A value that represents any error or warning that occurs when this node executes.