Computes the single-sided, scaled, cross power spectrum of two real-time signals.


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Inputs/Outputs

  • c1ddbl.png Signal X (V) —

    Signal X is the input, time-domain signal X, usually in volts.

    The time-domain record must contain at least three cycles of the signal for a valid estimate.

  • c1ddbl.png Signal Y (V) —

    Signal Y is the input, time-domain signal Y, usually in volts.

    The time-domain record must contain at least three cycles of the signal for a valid estimate.

  • cdbl.png dt —

    dt is the sample period of the time-domain signal, usually in seconds.

    Set dt to 1/fs, where fs is the sampling frequency of the time-domain signal. The default is 1.

  • i1ddbl.png Cross Power XY Spectrum Mag (V^2rms) —

    Cross Power XY Spectrum Mag is the single-sided cross power spectrum between signals X and Y.

    If the input signals are in volts (V), Cross Power XY Spectrum Mag has units of volts-rms squared (Vrms²). If the input signals are not in volts, Cross Power XY Spectrum Mag has units of the input signal unit-rms squared.

  • i1ddbl.png Cross Power XY Spectrum Phase (radians) —

    Cross Power XY Spectrum Phase is the phase spectrum in radians showing the difference between the phases of signal Y and signal X.

  • idbl.png df —

    df is the frequency interval of the power spectrum in hertz, if dt is in seconds.

    • The Cross Power Spectrum VI computes the single-sided cross power spectrum of Signal X and Signal Y. If Signal X and Signal Y have different lengths, the VI first pads the end of the shorter input signal with zeros to make the signals the same length. The VI then uses the following equation to compute the two-sided cross power spectrum:

    where N represents the common length of the two input signals after the VI pads the end of the shorter input signal with zeros.

    To compute the single-sided cross power spectrum, the VI converts the two-sided cross power spectrum to the single-sided form.

    df returns the frequency interval, which typically is used as the multiplier of the frequency axis in order to display the frequency domain.

    The cross power spectrum is an important concept for measurements. Refer to the Cross Power Spectrum conceptual topic for more information about the power spectrum.

    Note One difference between the Cross Power Spectrum VI and the Cross Power VI is that this VI returns the single-sided spectrum with the amplitude and phase as separate outputs, but the Cross Power VI returns the two-sided spectrum with the amplitude and phase as one complex output.