Three-dimension Simulation Model And Imaging Algorithms Of Multi-beam SAS

Nowadays,the resources of land are becoming less and less.But,the oceans are rich of flora and fauna and mineral resources.So,the oceans have become the focus of countries in the new century.In order to meet the need of country's production and people's life,it is very important to develop and use the oceans.At the same time,as the driven by the interests of the oceans,there is more conflict among countries.It becomes the key thing of country defence to safeguard oceans rights and safety.In view of this,the development and protection of the oceans needs efficient means of underwater exploration.The imaging sonar is very important because of a lot of information of the image.Multi-beam synthetic aperture sonar(SAS)is used for the oceans development and safeguard for its high-resolution and three-dimensional image.The text does research on multi-beam three-dimension simulation model and imaging algorithms of multi-beam SAS.The main contents include:(1)Do the research on the three-dimensional simulation model of multi-beam SAS.Because the texting in oceans is expensive and the texting needs simulation to test,simulation is an indispensable part.The text studies the model of array,the vehicle motion model,the echo signal of point target,shade of the target and the direction of emission array.These contents lay a theoretical foundation of multi-beam SAS.(2)The text completes the fractional delay beamforming.Because of wideband signals are widely used in underwater imaging field,the text studies beamforming technology in time domain.In order to obtain precise delay,the fractional delay beamforming is used in the paper.The paper completes the design of the fractional delay beamforming and illustrates the advantages of fractional delay beamforming.It also explains the depth can be got by beamforming,and completes the three-dimensional imaging of multi-beam SAS.(3)The paper does the research on the imaging algorithm of multi-beam SAS.According to the process of imaging,Firstly,the paper illustrates the principle of pulse compression technology and gives the pulse compression formulas of the chirp signal.Next,the paper gives the rules of point-by-point imaging algorithm of SAS and does the simulation and analysis the imaging results.Finally,the paper studies the theories of point-by-point imaging algorithm of multi-beam SAS and its improved imaging algorithm.Based on the imaging theories,the paper does the simulation experiments and gets the results of imaging.(4)The paper completes the design of tank experiment after the research of theories of multi-beam SAS and do the tank experiment and processing the data.