The location-estimating, null-steering (LENS) algorithm for adaptive microphone-array processing

This document develops and evaluates the Location-Estimating, Null-Steering (LENS) algorithm for adaptive array beamforming in the case of a. known target location. Such beamformers are useful in spatial-filtering applications that enhance a desired target source while attenuating non-target, jammer sources in a given environment. Although LENS is designed for general beamforming purposes, this document em­phasizes the use of LENS to create a background-noise-reducing hearing aid. LENS processing is innovative in that it uses a novel robustness-control mechanism to yield a beamformer that avoids target cancellation under adverse conditions. Most traditional beamforming systems realize robustness control through the use of con­straints in the beamforming optimization, which is an approach that is both indirect and difficult to understand. LENS, on the other hand, achieves direct and obvious ro­bustness control by separating robustness control from the beamforming optimization in the following two-step procedure: first it solves a minima.By-constrained beamform­ing optimization in terms of the LENS parameter set [beta]_oct , and then it evaluates and ... The advantages of LENS processing are not limited to improved system robust­ness, however. Its design allows implementation using a relaxation-based approx­imation to direct-solution LENS procGssing (the LENS equiwdent of direct covari­ance matrix inversion processing for traditional systems). Simulations demonstrate that this relaxation-based implementation can combine efficient implementation, fast beamformer adaptation, and good beamforming performance, which is difficult to achieve with traditional systems.

Department dc:contributor.department

Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

1998

Author dc:creator

• Desloge, Joseph Gilles

Advisor dc:contributor.advisor

• William M. Rabinowitz.

• Electrical Engineering and Computer Science

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/9606

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/9606