Research On Key Technology Of Multi-beam Sounding System

Multi-beam depth sounding system is a kind of equipment which can accurately measure the seabed.Whether it can achieve accurate measurement depends on its core technology signal processing system.From the basic principle of multi-beam sounding that only when the Angle estimation of measurement points is more accurate and the directivity of transmitting or receiving power is more concentrated,so the high resolution and high precision measurement of seabed topography can be realized.In addition,what kind of data filtering method can be used to process seabed data to form accurate seabed topographic map is also the research focus of multi-beam depth sounding system in the future.With the support of the open fund project of State Oceanic Administration,this paper studies two key technologies of multi-beam depth measurement system with high precision and high resolution and depth data point post-processing imaging.First,based on the principle of CBF,a cross-spectrum splitting subarray beamforming algorithm is proposed in this paper.First,the array is divided into two equal array elements,the two elements are beamforming respectively.Then the left and right subarrays are divided into four relative small arrays,and the cross spectrum analysis of the small array is carried out.Finally,the left and right beam sharpening is carried out for the main lobe constraint processing.Simulation results show that this algorithm has higher directivity than CBF.Second,LCMV is introduced in this paper.LCMV algorithm is very suitable for a variety of comprehensive sonar equipment because of its unique advantages.Since its basic theory is the power of concentrated signals,beamforming technology can be used for DOA estimation as well as improving the directivity of sonar transmitting and receiving signals to improve the signal power.Moreover,LCMV algorithm can be applied to detect complex seabed environment with multi-beam bathymetric sonar by recursively obtaining the optimal weight vector based on prior statistical characteristics.So a beamforming algorithm via Iterative Majorization and Reconstruction of Covariance Matrix is proposed.Based on the constraint condition of LCMV algorithm,the new constraint condition is deduced and the optimal weight vector of beamforming is solved to realize the high resolution detection of the signal.And based on the new constraints to reconstruct the covariance matrix to eliminate the effects of disturbance quantity in order to adapt to the complex time-varying environment,and then analysis of applying this algorithm was deduced on the circular array launch,at last,by simulation analysis in this paper,the algorithm is compared with the traditional LCMV algorithm to verify the superiority and effectiveness of the algorithm in this paper.Thirdly,rough processing of sounding points is carried out with the application of 3 criteria,and systematic engineering is established for the processed sounding data with the application of CARIS software,including removal of noise points,optimization of data and generation of seabed topography result map.