Computes the single-sided complex cepstrum of a univariate time series. This VI keeps the phase information of the input time series. You can reconstruct the original time series with the computed phase information and complex cepstrum. Wire data to the Xt input to determine the polymorphic instance to use or manually select the instance.


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Inputs/Outputs

  • cmsdt.png Xt —

    Xt specifies the univariate time series.

  • cerrcodeclst.png error in (no error) —

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

  • icclst.png cepstrum —

    cepstrum returns the cepstrum information about Xt.

  • idbl.png t0 —

    t0 returns the lower boundary of the time range.

  • idbl.png dt —

    dt returns the time increment.

  • i1ddbl.png C(t) —

    C(t) returns the resulting values of the complex cepstrum.

  • inclst.png phase info —

    phase info returns the phase information of Xt.

  • idbl.png DC —

    DC returns the phase information at zero frequency.

  • idbl.png Nyquist —

    Nyquist returns the phase information at the Nyquist frequency.

  • ierrcodeclst.png error out —

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

    • TSA Complex Cepstrum Details

    This VI computes the single-sided complex cepstrum C(t) of a univariate time series according to the following equation:

    C(t) = FFT-1{ln[FFT(Xt)]}

    where Xt is the univariate time series and FFT(Xt) is a complex array. FFT(Xt) = P(f)ejf(f).

    In order to make the definition unique, this VI unwraps f(f) and removes the linear phase, so the computed cepstrum does not contain the phase information of the original time series. This VI saves the phase values of f(f) at frequency zero and frequency p into phase info. You can reconstruct the original time series using the phase values and the complex cepstrum.

    Examples

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

    • Echo Canceling VI: labview\examples\Time Series Analysis\TSAApplications
    • Cepstrum Analysis VI: labview\examples\Time Series Analysis\TSAGettingStarted