Title page for ETD etd-52597-0349


Type of Document Master's Thesis
Author Tu, Yifeng
Author's Email Address tuy@stnick.me.vt.edu
URN etd-52597-0349
Title Multiple Reference Active Noise Control
Degree Master of Science
Department Mechanical Engineering
Advisory Committee
Advisor Name Title
Burdisso, Ricardo A.
Saunders, William R.
Fuller, Christopher R. Committee Chair
Keywords
  • eigenvalue spread
  • decorrelation filter
  • active noise cancellation
  • adaptive filter
Date of Defense 1997-03-25
Availability unrestricted
Abstract
The major application of active noise control (ANC) has been

focused on using a single reference signal; the work on

multiple reference ANC is very scarce. Here, the behavior

of multiple reference ANC is analyzed in both the frequency

and time domain, and the coherence functions are provided to

evaluate the effectiveness of multiple reference ANC.

When there are multiple noise sources, multiple reference

sensors are needed to generate complete reference signals.

A simplified method combines those signals from multiple

reference sensors into a single reference signal. Although

this method could result in satisfactory noise control

effects under special circumstances, the performance is

generally compromised. A widely adopted method feeds each

reference signal into a different control filter. This

approach suffers from the problem of ill-conditioning when

the reference signals are correlated. The problem of

ill-conditioning results in slow convergence rate and high

sensitivity to measurement error especially when the FXLMS

algorithm is applied. To handle this particular problem,

the decorrelated Filtered-X LMS (DFXLMS) algorithm is

developed and studied in this thesis.

Both simulations and experiments have been conducted to

verify the DFXLMS algorithm and other issues associated

with multiple reference ANC. The results presented herein

are consistent with the theoretical analysis, and favorably

indicate that the DFXLMS algorithm is effective in improving

the convergence speed.

To take the maximum advantage of the TMS320C30 DSP board

used to implement the controller, several DSP programming

issues are discussed, and assembly routines are given in

the appendix. Furthermore, a graphical user interface (GUI)

running under Windows' environment is introduced. The main

purpose of the GUI is to facilitate parameters modification,

real time data monitoring and DSP process control.

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