摘要:
本文介绍浅海远程声场空间相关的一些实验结果。实验研究了不同距离、频率与带宽的空间相关,测量数据具有明显的距离与频率依赖关系。实验结果表明,在55至130公里的传播距离上跃变层之下的低频声场有较强的空间相关性与时间稳定性。
Abstract:
The experimental results of spatial correlation and temporal stability of long-range sound field in shallow water are presented. Two experiments had been made. The first experiment was conducted in shallow water with depth 38 m, the source-and received-depth was 7 m and 6 m respectively, the longitudinal spatial correlation above the thermoc-line was studied mainly. The longitudinal correlation curves for frequency 1.0kHz at ranges 1.4, 6.4 and 16 km revealed that the stronger spatial correlation presented at longer range. Prom experiment it was also observed that received signals had complex but similar multi-path structure.
The second experiment was conducted in shallow water with depth 60 m, source depth was 25 m and receivers were located at bottom. The transverse correlation, the longitudinal correlation, the horizontal angular spreading and the temporal stability of sound field below the thermocline were studied. The measurements and analyses were made at ranges 55, 93, 130 km for narrow-band signals of frequencies 0.5 and 1.0 kHz with width 1/3 oct and for wide-band signals of frequencies from 0.2 to 0.8 kHz. The experimental results showed that （1） the long-range sound field has strong spatial correlation, for example, the transverse spatial correlation length of wide-band signal at range 130 km is larger than 420 m; （2） the long-range sound field has small horizontal angular spreading, for example, the horizontal angular spreading of wide-band signal at range 130 km is less than 0.13; （3） the waveform of received signals has strong temporal stability, for example, the temporal correlation length of wide-band signal at rage 130 km is more than 312 second.
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