Power Spectrum

LabVIEW SignalExpress

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Power Spectrum

Computes the averaged magnitude spectrum, power spectrum, or power spectral density for a single or multiple channels. This step can return the spectra in root-mean-square, peak, and peak-to-peak units.

ParameterDescription
GraphSpectra—Displays the spectra for all channels. Use the Zoom button to zoom in and out of the display.

Signals—Displays the time-domain signals for all channels. Use the Zoom button to zoom in and out of the display.
ViewSpecifies if the graph displays time domain signals or the computed power spectra.
AutoscaleAutomatically adjusts the scales of the graph to display the data.
InputContains the following option:
  • Input signal—Specifies the analog waveform for the step.
ConfigurationContains the following options:
  • Window—Specifies the window to apply to the input signal. Choose from one of the following window options:
    • None
    • Hanning
    • Hamming
    • Blackman-Harris
    • Exact Blackman
    • Blackman
    • Flat Top
    • 4 Term B-Harris (Four Term Blackman-Harris)
    • 7 Term B-Harris (Seven Term Blackman-Harris)
    • Low Sidelobe
    • Gaussian
  • Scaling—Specifies the scaling parameter for the step.
    • Spectrum type—Specifies if the spectrum is in units of Magnitude or Power, where power equals magnitude squared. The default is Power.
    • Magnitude scale—Specifies if zoom power is in linear units or in decibels. The default is decibels.
    • Peak conversion—Specifies the peak scaling of the converted spectrum. You can select RMS (default), Peak, or Peak to Peak.
    • Spectral density—Specifies if the spectrum is returned as power spectral density (PSD). The default is Off.
AveragingSpecifies the averaging parameters.
  • Averaging mode—Specifies the averaging mode from the following options:
    • No Averaging (Default)
    • Vector Averaging
    • RMS Averaging
    • Peak Hold
  • Weighting mode—Specifies either Exponential or Linear weighting. Exponential averaging applies more weight to the most recent data, and linear averaging applies equal weighting to all the data.
  • Number of averages—Specifies the number of averages used by the selected Weighting mode.
  • Auto-restart—Specifies if the averaging process automatically restarts once the step reaches the Number of averages value. When you set Weighting mode to linear, use Auto-restart to configure averaging to automatically restart when Averages completed equals the Number of averages.
  • Averages completed—Displays the number of averages completed.
  • Averaging done—Indicates when the number of Averages completed equals or exceeds the Number of averages. Averaging done is always TRUE if the selected Averaging mode is No averaging.
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