Like-Envelope Recombination: A Technique for Recombining Dependent Intrinsic Mode Functions

Open Access
Author:
Hildebrandt, Timothy John
Graduate Program:
Acoustics
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
August 17, 2015
Committee Members:
  • David Carl Swanson, Thesis Advisor
Keywords:
  • Empirical Mode Decomposition
  • Intrinsic Mode Functions
  • Signal Recombination
  • Signal Processing
  • Signal Decomposition
Abstract:
The single-most complicating fact in any signal analysis application is this – no real-life signal is comprised solely of the required information for any given application. In any system, noise must be filtered, extraneous signals must be accounted for, and in most instances the signal in question is actually comprised of the outputs of multiple sources. The Empirical Mode Decomposition (EMD) algorithm and its many flavors were developed as a way to divide these complex signals into a collection of source-specific, mono-component signals. The reality of this algorithm however, is that the signal is too often over-decomposed. The Like-Envelope Recombination (LER) algorithm was developed as a post-decomposition tool that can be used to pull similar signal components back together in an effort to create simple signals that directly correlate to some physical aspect of the system in question. The basis of the LER algorithm is the idea that signal components that are generated by the same source will have similar amplitude structures. This algorithm has largely been a success, but still requires manual intervention to complete the recombination process for more complex signals. This thesis details the specifics of both the EMD and the LER algorithms and provides examples and references for the algorithms and how they might be applied. It is found that, when used appropriately, the EMD/LER algorithm combination can be a successful tool for research and teaching purposes. However, due to a high complexity level, these algorithms remain impractical for real-time analysis application.