OriginLab Technical Support

3/24/2021

4/27/2021

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Empirical ...on.opx

1

Free

Perform empirical mode decomposition

**Purpose**

This tool can be used to perform empirical mode decomposition, also perform the spectrum analysis, including frequency transform and Hilbert-Huang transform.

**Installation**

Download the file Empirical Mode Decomposition.opx, and then drag-and-drop onto the Origin workspace. An icon will appear in the Apps gallery window.**Operation**

With the signal column in worksheet selected, click the app icon from the Apps gallery window. Then a dialog will pop up, then change the settings in dialog accordingly, then click OK button.**Dialog Setings**- Input tab
- Input: Specify the input signal. You can select from the context menu, or open the Column Browser from the context menu, and then select signal column.

- Sifting tab
- Threshold: Specify the threshold at which the overall sifting process will stop.
- Maximum IMFs: Specify how many IMFs (Intrinsic Mode Functions) to compute. The maximum number of IMFs to compute. If Auto (-1), it will compute IMFs until the stop condiction is met.
- Show IMF Options: Check to show the options for computing the next IMF from a dataset.
- Show Envelope Options: Check to show the options for interpolating the amplitude envelope of a signal.
- Show Extrema Options: Check to show the options for identifying and pading the extrema in a signal.
- IMF Options group:
- Scale Factor: The average of the upper and lower envelope is multiplied by this value before being subtracted from the data. This value should be between 0 and 1 (exclude 0 but include 1).
- Maximum Iterations: Maximum number of iterations to compute.
- Energy Diff. Threshold (in Decibels): Threshold for energy difference (in decibels) between IMF and residual to stop overall sift.
- Stop Method: How to stop sifting. Options include Standard Deviation Threshold, Rilling Metric and Fixed Number.
- St. Dev. Threshold: When Stop Method is Standard Deviation Threshold, this value is the threshold at which the sift of each IMF will be stopped.
- Rilling Metric: When Stop Method is Rilling Metric, an evaluation function (E) is defined by dividing the residual by the mode amplitude. The sift continues until E < sd1 for the fraction (1-alpha) of the data, and E < sd2 for the remainder. This parameter is for specifying sd1, sd2, and alpha sequentially, separated by space.

- Envelope Options group:
- Interpolation Method: Specify interpolation method used for interpolating the amplitude envelope of a signal. Options include B-Spline and PCHIP 1-D Monotonic Cubic.

- Extrema Options group:
- Pad Width: Number of additional extrema to add to the start and end.
- Parabolic Extrema: check to refine the extrema positions by parabolic interpolation.
- Pad Extrema Magnitude Options group
- Statistic Length: How many data to use for calculating the statistic for padding extrema magnitudes.

- Spectrum Analysis tab
- Frequency Transform: Check to perform frequency transform.
- Frequency Transform Options group
- Sample Rate (Hz): Specify sampling rate. If Auto, it will compute from the X of the signal.
- Method: The method for computing the frequency stats. Options include Hilbert Transform, Quadrature Transform, Direct Quadrature Transform, and Amplitude Normallized Hilbert Transform,
- Window Length for Smooth Phase: Specify length of window when smoothing the unwrapped phase.

- Hilbert-Huang Transform: Check to perform Hilbert-Huang Transform. Also, frequency transform is performed together.
- Hilbert-Huang Transform Options group
- With Time Dimension (2D): Check to consider the time dimension, that is, if checked, the Hilbert-Huang transform instataneous frequency and instantaneous amplitude time-series and represents the energy of a signal across time and frequency, if not checked, only across frequency.
- Instantaneous Amplitude Weighted: If checked, instantaneous amplitude is used as weight, otherwise, no weight is used.
- Frequency Start From: The start value of frequency range.
- Frequency End At: The end value of frequency range.
- Number of Frequencies: How many frequencies is used for the frequency range.
- Frequency Type: Specify to use Linear or Ln spacing for frequency.
- Mode: Specify the mode of sum, Energy or Amplitude.

- Output tab
- Output: Specify where to output the results. New Sheet will create new sheet in the same workbook of the source signal for the results, and New Book will create a new workbook for the results.

- OK and Cancel Buttons: Click OK button to output the results and close dialog, and click Cancel button to close the dialog only.

- Input tab
**Note:**The algorithm used in this app is from this page, for more details about algorithm, please refer to that page.

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