声学
宽带
折射
信号(编程语言)
物理
到达方向
光学
航程(航空)
地质学
天线(收音机)
计算机科学
电信
材料科学
复合材料
程序设计语言
作者
Alexander G. Voronovich,Vladimir E. Ostashev,John A. Colosi,Bruce D. Cornuelle,Brian D. Dushaw,Matthew A. Dzieciuch,Bruce M. Howe,James A. Mercer,Robert C. Spindel,Peter F. Worcester
出处
期刊:Journal of the Acoustical Society of America
[Acoustical Society of America]
日期:2001-05-01
卷期号:109 (5_Supplement): 2385-2385
被引量:2
摘要
A comprehensive, long-range sound propagation experiment was carried out with the use of the billboard acoustic array of the North Pacific Acoustic Laboratory (NPAL) in 1999. The antenna consisting of five vertical line arrays was deployed near a California coast and received broadband acoustic signals transmitted from Hawaii over a distance of about 4000 km. Acoustic signals propagating over such a long distance might exhibit noticeable horizontal refraction. The paper will present results of processing the NPAL data to infer horizontal refraction angle (HRA) as a function of time. Different methods were used for determining HRA. The first approach employed cross correlation of the acoustic signals at different VLAs. Time delay corresponding to maximum of cross correlation is related to HRA assuming the angle is approximately the same for all rays (or modes). The second method used modal representation of the arriving broadband signals. The dependency of the amplitudes of acoustic modes on mode number, frequency, and arrival angle was determined independently within narrow frequency bins, and then the results were averaged over whole frequency range. This method allowed, in particular, to evaluate angular width of the arrived signal, which appeared to be of the order of a few milliradians.
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