Characterizing urban noise sources using beamforming technology

Pao Yue-kong Library Electronic Theses Database

Characterizing urban noise sources using beamforming technology

 

Author: Tam, Kai-chung
Title: Characterizing urban noise sources using beamforming technology
Degree: M.Eng.
Year: 2007
Subject: Hong Kong Polytechnic University -- Dissertations.
City noise -- Measurement.
Antenna arrays.
Signal processing -- Digital techniques.
Adaptive signal processing.
Department: Dept. of Building Services Engineering
Pages: xii, 91, 43 leaves : ill. (some col.) ; 30 cm.
Language: English
InnoPac Record: http://library.polyu.edu.hk/record=b2117601
URI: http://theses.lib.polyu.edu.hk/handle/200/2382
Abstract: Delay and sum beamforming is one of the array signal processing technologies which is based on far field signal assumption in identifying the noise sources directions and locations. The far field signal assumption take advantage in environmental noise identification especially for some adverse environment where it is unavailable for measurement setup. This study focused on two areas, the study of the performance of fundamental linear array with non-linear position approach and flexibility study of the beamforming system in environmental noise source identification. In non linear array study, converging and diverging functions were used as the governing boundary of the microphone position. The 3dB beamwidth and maximum side lobe level were the assessment parameters for the performance of the arrays. In beamforming measurement, the 42 channels microphone array beamforming system measured three different scenarios, including the stationary noise, traffic noise and train noise. The findings indicated that the angular resolution of linear are array affected by microphone position. Mean co-array sensor to sensor distance and co-array distribution are available for predication of the angular resolution of linear array. Also, co-array distribution points out the variance of maximum side lobe level of different array configuration. The beamforming system shows representative result in noise sources identification. However, the performance of the system relies on the dominance of the sound sources and its frequency distribution. This dissertation provides suggestion of farther study of co-array distribution in planar array and recommends some points to note for beamforming measurement for moving noise sources.

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