Waddington, DC and Angus, JAS 2007, 'Spread spectrum technique for the study of outdoor noise propagation' , Journal of the Acoustical Society of America, 122 (5) , pp. 2669-2678.

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Abstract

This paper describes field measurements to assess innovative correlation techniques for the study of meteorological and topographical effects on sound propagation. To take advantage of the properties of coded signals in a time-varying system, the correlation signal is produced by the modulation of a code sequence onto an acoustic carrier. An established method of increasing signal-to-noise ratio is to use correlation techniques with maximum length sequences. However, this standard method is restricted in its use outdoors because of the time-variant nature of the atmosphere. On the other hand, the correlation properties of a directly carrier-modulated code sequence modulation signal may be exploited in a time-varying environment. An experiment is described in which the correlation properties of the spread spectrum signal are demonstrated and are used to calculate accurate times of flight that compare well with sonic anemometer measurements of speed of sound. The results illustrate that an acoustical spread spectrum system can provide significantly improved ways of measuring sound propagation outdoors.

Item Type:	Article
Uncontrolled Keywords:	acoustic correlation, acoustic noise, acoustic wave propagation, atmospheric acoustics
Themes:	Subjects / Themes > Q Science > QC Physics > QC221-246 Acoustics - Sound Subjects outside of the University Themes
Schools:	Colleges and Schools > College of Science & Technology > School of the Built Environment Colleges and Schools > College of Science & Technology > School of Computing, Science and Engineering > Acoustics Research Centre
Journal or Publication Title:	Journal of the Acoustical Society of America
Publisher:	Acoustical Society of America
Refereed:	Yes
ISSN:	00014966
Depositing User:	H Kenna
Date Deposited:	03 Oct 2007 15:09
Last Modified:	27 Sep 2011 12:17
URI:	http://usir.salford.ac.uk/id/eprint/500

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