Elastic wave on seafloor caused by low frequency noise radiated from ship is called ship seismic wave which can be used to identify ship target. In order to analyze the wave components and the propagating properties o...Elastic wave on seafloor caused by low frequency noise radiated from ship is called ship seismic wave which can be used to identify ship target. In order to analyze the wave components and the propagating properties of ship seismic wave, the numerical calculation of synthetic seismograms on seafloor aroused by a low frequency point sound source is carried out using a wave number integration technique combined with inverse Fourier transform. According to the numerical example of hard seafloor, the time series of seismic wave on seafloor are mostly composed of interface waves and normal mode waves. Each normal mode wave has a well defined low cut-off frequency, while the interface wave doesn't have. The frequency dispersion of normal mode wave is obvious when frequency is lower than 100Hz, while the interface wave is dispersive only in the infra-sound frequency range. The time series of seismic wave is dominated by the interface wave when the source frequency is less than the minimal cut-off frequency of normal mode wave.展开更多
本文系统阐述了自行研发的半球型麦克风阵列的点声源定位系统智能检测前端的设计与实现。本系统以STM32单片机为核心、以半球形麦克风阵列为声源检测单元、与信号调理模块及数据传输模块共同构建一个智能检测前端,针对点声源以不同的角...本文系统阐述了自行研发的半球型麦克风阵列的点声源定位系统智能检测前端的设计与实现。本系统以STM32单片机为核心、以半球形麦克风阵列为声源检测单元、与信号调理模块及数据传输模块共同构建一个智能检测前端,针对点声源以不同的角度和方位同步实时多点采集噪声信息,并对多点信号同步归一化处理。经过测试本智能检测前端噪声分辨率0.1 d B。展开更多
基金Sponsored by National Nature Science Foundation of China ( 51179195)National Defense Foundation of China ( 513030203-02)
文摘Elastic wave on seafloor caused by low frequency noise radiated from ship is called ship seismic wave which can be used to identify ship target. In order to analyze the wave components and the propagating properties of ship seismic wave, the numerical calculation of synthetic seismograms on seafloor aroused by a low frequency point sound source is carried out using a wave number integration technique combined with inverse Fourier transform. According to the numerical example of hard seafloor, the time series of seismic wave on seafloor are mostly composed of interface waves and normal mode waves. Each normal mode wave has a well defined low cut-off frequency, while the interface wave doesn't have. The frequency dispersion of normal mode wave is obvious when frequency is lower than 100Hz, while the interface wave is dispersive only in the infra-sound frequency range. The time series of seismic wave is dominated by the interface wave when the source frequency is less than the minimal cut-off frequency of normal mode wave.
文摘本文系统阐述了自行研发的半球型麦克风阵列的点声源定位系统智能检测前端的设计与实现。本系统以STM32单片机为核心、以半球形麦克风阵列为声源检测单元、与信号调理模块及数据传输模块共同构建一个智能检测前端,针对点声源以不同的角度和方位同步实时多点采集噪声信息,并对多点信号同步归一化处理。经过测试本智能检测前端噪声分辨率0.1 d B。
