浅海内波引起的声场时间相关特性研究
文献类型：学位论文
| 作者 | 季桂花 |
| 学位类别 | 博士 |
| 答辩日期 | 2009-05-27 |
| 授予单位 | 中国科学院声学研究所 |
| 授予地点 | 声学研究所 |
| 关键词 | 线性内波 孤立子内波 匹配场 时间相关 时间相关长度 |
| 其他题名 | Effects of the internal waves on the temporal correlation of acoustic field in shallow water |
| 学位专业 | 声学 |
| 中文摘要 | 声信号的时间相关能确定与相位有关的水声通讯算法的比特率和误码率，以及其他对相位敏感的信号处理算法如匹配场处理的信号增益。在起伏的海洋中，由于内波等海洋动力学过程的存在，接收声场是时变的。一般内波活动是声场时间相关半径减小的一个重要原因。因此本文利用两次浅海实验的水文数据仿真了存在内波时的声场，并分析了浅海内波对匹配场时间相关的影响。 本文利用1996年中美远黄海实验的水文数据，通过数值仿真研究了浅海环境中存在线性内波和孤立子内波时声场的匹配场时间相关性，考察和总结了有内波存在时不同声源频率、声源深度和内波幅度等参数对匹配场时间相关的影响。研究结果表明：由于内波与声场的相互作用，匹配场时间相关长度会随着线性内波的平均能流密度或孤立子内波幅度的增大而减小；频率越高，声波穿过内波场时的匹配场时间相关下降的越快；声源位于跃层下时的匹配场时间相关明显的优于声源位于跃层上的情况；孤立子内波距声源的位置对匹配场时间相关的影响相对较小。在以上工作基础上，分析了存在线性内波时远黄海海洋环境中匹配场时间相关长度与声源频率和声速起伏的关系，得到了声源位于跃层上和跃层下时匹配场时间相关长度的经验表示。 在分析ASIAEX2001南中国海实验水文数据的基础上，得到了该海域的内波频谱和特征参数。并利用得到的内波频谱和特征参数仿真该海域存在线性内波时的声速场及声场，分析了匹配场时间相关长度与声源频率、声速标准差和收发距离之间的关系，并拟合得到了匹配场时间相关长度的经验公式。结果表明：在两种浅海水文条件下匹配场时间相关长度与内波引起的声速标准差之间的关系相近，分别为δC -1.4或δC -1.3成正比；两种水文条件下匹配场时间相关长度分别与f -1.3与f -1.1成正比；在南中国海水文条件下，海底水平不变和水平变化时匹配场时间相关长度分别与R-0.7和R-0.5成正比。 |
| 英文摘要 | The signal temporal correlation can determine the bit rate and error rate in underwater acoustic communication, and the maximum temporal processing gain for other signal processing sensitive to the phase variability. Acoustic signals propagating through the time-varying shallow water environment will fluctuate with time. Usually the activity of internal waves is one of the main reasons of the decrease of temporal correlation length. So acoustic field is simulated in the environment with internal waves based on two experimental oceanic data in this dissertation, and the effect of internal waves on the temporal correlation of acoustic field in shallow water is analyzed. Effects of linear and solitary internal waves on the temporal correlation of matched-field processing (MFP) in shallow water are numerically investigated for acoustic sources with different frequencies and depths based on oceanographic data from the 1996 joint China-USA Far Yellow-Sea experiment. It is shown that the temporal correlation of MFP decreases as the average energy density of linear internal waves or the amplitude of solitary internal waves increased. For acoustic source with lower frequency or located below the thermocline, the temporal correlation of MFP is less affected by internal waves, and the temporal correlation length of MFP is longer. Moreover, the effects of the range from solitary internal waves to acoustic source on the temporal correlation of MFP are relatively small. The frequency spectrum and parameters of internal wave are obtained by analyzing the oceanographic data from the ASIAEX2001 South China Sea experiment, and the relationship between the signal temporal correlation length of MFP and the acoustic frequency, the source-receiver range, and the sound speed standard deviation (STD) caused by internal waves in shallow water is numerically investigated based on oceanographic data from the two experiments. It is found that the coherence-time can be fitted with an inverse 1.3 or 1.1 power of frequency, and inverse 1.4 or 1.3 power of sound speed STD in the two environments. In South China Sea environment, the temporal correlation can be fitted with an inverse 0.7 and 0.5 power of range when the bottom is range-independent and range-dependent respectively. |
| 语种 | 中文 |
| 公开日期 | 2011-05-07 |
| 页码 | 81 |
| 源URL | [http://159.226.59.140/handle/311008/450]  |
| 专题 | 声学研究所_声学所博硕士学位论文_1981-2009博硕士学位论文 |
| 推荐引用方式 GB/T 7714 | 季桂花. 浅海内波引起的声场时间相关特性研究[D]. 声学研究所. 中国科学院声学研究所. 2009. |
入库方式： OAI收割
来源：声学研究所
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