View Item 
        •   Huskie Commons Home
        • Dissertations and Theses
        • Dissertations and Theses
        • View Item
        •   Huskie Commons Home
        • Dissertations and Theses
        • Dissertations and Theses
        • View Item
        JavaScript is disabled for your browser. Some features of this site may not work without it.

        Adaptive signal processing and its application to Echo canellations in telecommunications

        Thumbnail
        View/Open
        Chen, Jier.pdf (1.309Mb)
        Date
        1992
        Author
        Chen, Jier
        Metadata
        Show full item record
        Abstract
        In teleconferencing, the introduction of the acoustic echo canceller by using an adaptive transversal filter is the most effective technique of controlling the acoustic echoes. However, the requirement of a high order filter for modeling the long acoustic echo impulse responses results in difficulties in convergence and hardware implementation. This problem becomes even worse in multiple microphone systems. A Partial Adaptive Process (PAP) is developed and studied in this thesis. This method utilizes the exponential decay characteristics of the echo impulse response; therefore, the significant portion of the echo impulse response is modelled by a smaller size filter. Analyses and simulations have been made to estimate the performance of this finite length filter in the steady-state. Results show that the echo canceller will have smaller residual error for speech signal than white noise. Acoustic theory is used to effectively demonstrate how the minimum mean squared error is affected by the dynamically changing impulse response and the effect of using a finite filter order. Results indicate that a large filter will slow down the convergence rate and increase the system error, thus preventing further system performance in acoustic echo cancellation. The small order filter using the PAP method has been shown to be effective. Other filter structures and algorithms in complement to the PAP are introduced. Their improvement in terms of performance and computational savings are discussed. Finally, a new adaptive notch filter is developed and is applied to control the howling phenomenon found in the speakerphone systems.
        URI
        http://commons.lib.niu.edu/handle/10843/15356
        Collections
        • Dissertations and Theses

        DSpace software copyright © 2002-2016  DuraSpace
        Contact Us | Send Feedback
        Theme by 
        Atmire NV
         

         

        Browse

        All of Huskie CommonsCommunities & CollectionsBy Issue DateAuthorsTitlesSubjectsThis CollectionBy Issue DateAuthorsTitlesSubjects

        My Account

        Login

        Copyright

        Copyright, Access, and Withdrawal Information

        DSpace software copyright © 2002-2016  DuraSpace
        Contact Us | Send Feedback
        Theme by 
        Atmire NV