Multi Base Reverberation Signal Acquisition And Spatial Correlation Analysis

The reverberation signal is generated along with the sound source signal,which causes significant interference to the active sonar.This phenomenon is especially noticeable in the near-range reverberation environment.The reverberation restricts the application of the active sonar system and the related data analysis,So the research on ocean reverberation has extremely important significance.The effective collection of reverberation signal is the basis of reverberation research.The reverberation signal has the characteristics of large dynamic range.The reverberation signal acquisition system needs to be designed according to the characteristics of reverberation signal.This thesis developed a set of reverberation signal acquisition system,involving the acquisition system hardware and software design and production debugging.The hardware circuit mainly includes independent power supply circuit,analog conditioning board and digital acquisition control board.Completion of the reverberation signal pickup,amplification,filtering,acquisition,storage and upload functions.The software mainly completes the driving of the acquisition chip,real-time data collection,data storage,command control system working status and high-speed data transmission.The performance of each module of the system,the overall performance of the system made a test analysis,performance indicators are good.Because of the large dynamic range of reverberation signal,the system uses a highresolution AD converter to ensure that any signal amplitude in the case,have a high acquisition accuracy.The system uses battery-powered,in order to achieve the purpose of mobile work.The circuit design is designed with low noise,low power consumption and large dynamic range.The hardware circuit is based on the field programmable logic array(FPGA)and each hardware circuit uses the idea of separate modules,to facilitate the improvement of system functions and the number of acquisition system channels increased.On the basis of this,this paper studies the characteristics of reverberation signal model and reverberation signal.Most of our waters are shallow sea areas,while large reef submarine structures occur near reefs or islands.The main influencing factor of the short-range reverberation in these areas is the seabed reverberation.Therefore,based on the theory of ray acoustics and the principle of superposition of sound field,the propagation of sound waves follows the spherical expansion and calculates the three-dimensional scattering coefficient of the seafloor by the Ellis three-dimensional scattering model.Only the primary scattering effect of the seafloor is considered,and the multi-base reverberation Signal simulation model.The simulated reverberation signal is analyzed and processed in terms of the statistical distribution of instantaneous amplitude and instantaneous phase,the probability density distribution of the reverberation signal envelope,and the spatial correlation of different marine environments and spatial structures.The envelope probability density distribution of the collected experimental data of the reverberation signal is analyzed,which is closer to the Rayleigh distribution than the envelope probability density of the simulation signal.Because acquired reverberation data characteristics are in line with the general characteristics of reverberation signals,which also proves that the third chapter of the reverberation data acquisition system is reliable and practical.The conclusions obtained in this paper can provide references for the modeling of reverberation signal and its related characteristics.