The Research Of Multi-beam Underwater Detection Based On Spread Spectrum

Underwater multibeam sounding system as one of the key technology in the modernocean exploration based on the traditional single-beam bathymetric technology, It can formmultiple different angles of the probe beam underwater, to achieve high efficiency, highprecision and high coverage of the seabed measurement result to the measurement ofefficiency has been greatly improved. Therefore, the multi-beam bathymetric system isparticularly suitable for large area sweeping sea survey workAll multi-beam bathymetric systems based on single-frequency echo sounding. However,due to the complexity of the underwater environment, the channel has attenuation andmultipath interference seriously, and the density and temperature the of water will also havean impact on the measurement results. Besides, traditional pulse detection has contradictionsbetween the range resolution and detection depth.A good method against frequency-selective fading and multipath effects is spreading,andspread spectrum has no contradictions about detection range and high resolution. It isconsidered a very effective way.This paper propose a new method that add the spreadspectrum technology to multi-beam bathymetric system in order to overcome these problems,and improve underwater multibeam bathymetric accuracy, meanwhile we make theexperimental simulation about the research.The main work of this paper is divided into three parts:Firstly，the key technologies of Multi-beam bathymetry is introduced, including systemstructure，basic principle, beam forming, bathymetric algorithm and data correction. Specially,the beam forming and bathymetric algorithm are analyzed in detail.Secondly，describes the principles and methods of spread spectrum technology, focusingon DS. A new multi-beam bathymetric system based on DS is built, and improve thealgorithm, theoretically proves the feasibility of the system and performance benefits.Finally, in order to facilitate further study of this paper presents the theory, we buildundersea reversal model, and simulate the model of the traditional multi-beam bathymetricalgorithms and the proposed spreading multibeam bathymetric algorithm measurement in themodel, throughthe comparative analysis of the results confirmed the validity of the theory ofthis thesis.