Time Series Bispectrum Express VI

Owning Palette: Correlation and Spectral Analysis VIs

Requires: Advanced Signal Processing Toolkit

Computes the single-sided bispectrum of a univariate time series.

Dialog Box Options

Block Diagram Inputs

Block Diagram Outputs

Dialog Box Options

Parameter	Description
Data Source	Specifies whether this Express VI reads data from a block diagram input terminal or from a file. From terminal specifies that this Express VI reads data from a block diagram input terminal. From file specifies that this Express VI reads data from a file. This Express VI can read data from waveform, WAV, or TXT files. The valid format of a TXT data file is a file that contains only a 1D real array.
File Path Configuration	Contains the following options: File path—Specifies and displays the path to the file from which this Express VI reads data. This option is available only when you select From file in the Data Source section. Prompt to choose a file each time this VI runs—Specifies whether this Express VI displays a dialog box that prompts you to select a file each time this Express VI runs. This option is available only when you select the From file option in the Data Source section.
Signal and Window	Displays the signal and window. Contains the following option: Display window—Specifies to display the windows that you apply to the time series. This option is available only when you select FFT in Method.
Bispectrum	Contains the following options: dB—Specifies to return the results in decibels. The default is TRUE. Bispectrum—Displays the bispectrum.
Algorithm Settings	Contains the following options: Frequency bins—Specifies the number of frequency bins for which this VI computes the bispectrum. The resulting bispectrum is a square array. Method—Specifies the method to use in computing the bispectrum. Options include FFT (default) and AR Model. Window—Specifies the time-domain window you apply to the time series. Options include Hanning, Hamming, Blackman-Harris, Exact Blackman, Blackman, Flat Top, 4 Term B-Harris, 7 Term B-Harris, and Low Sidelobe. This option is available only when you select FFT in Method. Window length—Specifies the length of the window. A large window size leads to a small variance and a large bias of the bispectrum, and vice versa. This option is available only when you select FFT in Method. Overlap—Specifies the overlap of the moving window applied to a time series as a percentage. This option is available only when you select FFT in Method. Method of AR Model—Specifies the method to use in estimating the autoregressive model. Options include Forward-Backward (default), Least-Squares, Yule-Walker, Burg-Lattice, and Geometric-Lattice. This option is available only when you select AR Model in Method. AR order—Specifies the order of the autoregressive model. The default is 40. This option is available only when you select AR Model in Method.
Averaging Parameters	Specifies how this VI computes the averaging. Contains the following options: Averaging mode—Specifies the averaging mode. Options include No Averaging (default), Vector Averaging, RMS Averaging, and Peak Hold. Weighting mode—Specifies the weighting mode for RMS and vector averaging. Options include Linear and Exponential (default). Number of averages—Specifies the number of averages used for RMS and vector averaging. If Weighting mode is exponential, the averaging process is continuous. If Weighting mode is linear, the averaging process stops after this VI computes the selected Number of averages.

Block Diagram Inputs

Parameter	Description
error in (no error)	Describes error conditions that occur before this node runs.
Xt	Specifies the time series. Xt is available only when you select From terminal in Data Source.
File path	Specifies the file path of the data you want to load. This input is available only when you select the From file option in the Data Source section.

Block Diagram Outputs

Parameter	Description
averaging done?	Returns whether the averaging process is complete. averaging done? returns TRUE when the number of averages this VI completes is greater than or equal to the Number of averages. Otherwise, averaging done? returns FALSE. averaging done? is always TRUE if the Averaging mode is No Averaging.
error out	Contains error information. This output provides standard error out functionality.
freq bins	Returns the frequency bins at which this VI estimates the bispectrum.
Sxxx	Returns the magnitude of the single-sided bispectrum, S(f1, f2).
unit	Returns the selected engineering unit of the estimated power spectral density.

This Express VI operates similarly to the following VIs and functions:

TSA Bispectrum