Computes the single-sided power spectral density (PSD) of a univariate time series using the periodogram method. The periodogram method is a fast Fourier transform (FFT) based method that estimates the PSD. Wire data to the Xt input to determine the polymorphic instance to use or manually select the instance.


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Inputs/Outputs

  • cdbl.png sampling rate —

    sampling rate specifies the sampling rate, in hertz, of the univariate time series Xt. The default is 1.

  • ci32.png frequency bins —

    frequency bins specifies the number of frequency bins for which this VI computes the single-sided power spectral density PSD. The length of the single-sided PSD is (frequency bins/2+1). The default is 1024.

  • c1ddbl.png Xt —

    Xt specifies the univariate time series.

  • cu16.png window —

    window specifies the time-domain window applied to the time series. Options include None (default), Hanning, Hamming, Blackman-Harris, Exact Blackman, Blackman, Flat Top, 4 Term B-Harris, 7 Term B-Harris, and Low Sidelobe.

  • cerrcodeclst.png error in (no error) —

    error in describes error conditions that occur before this node runs. This input provides standard error in functionality.

  • cbool.png dB on? (T) —

    dB on? specifies whether this VI returns the PSD in decibels or in a linear scale. If dB on? is TRUE, this VI returns the PSD in decibels. If dB on? is FALSE, this VI returns the PSD in a linear scale. The default is TRUE.

  • icclst.png PSD —

    PSD returns information about the single-sided power spectral density (PSD).

  • idbl.png f0 —

    f0 returns the lower boundary, in hertz, of the frequency range.

  • idbl.png df —

    df returns the frequency increment, in hertz.

  • i1ddbl.png S(f) —

    S(f) returns the magnitude of the PSD at each frequency. The value of dB on? determines the unit of measurement for this parameter.

  • ierrcodeclst.png error out —

    error out contains error information. This output provides standard error out functionality.

    • TSA Periodogram Details

    This VI computes the PSD of a time series using the periodogram method according to the following equation:

    where S(f) is the PSD of the time series. df is the frequency interval, which is computed as fs/N. NBW is the noise power bandwidth of the window. N is the number of frequency bins. fs is the sampling rate. Before computing the PSD, this VI wraps the original time series Xt to an N-point series Xt'.

    Examples

    Refer to the following VIs for examples of using the TSA Periodogram VI:

    • Average PSD VI: labview\examples\Time Series Analysis\TSAGettingStarted
    • Beam Crack Detection VI: labview\examples\Time Series Analysis\TSAApplications
    • Power Spectral Density Estimation VI: labview\examples\Time Series Analysis\TSAGettingStarted