Maximum Entropy Method For Ocean Acoustic Tomography

In 1979,W.Munk proposed the method of ocean acoustic tomography,using acoustic propagation to monitoring the meso-scale ocean.This method is aimed to solve the inverse media problem by estimating the sound speed and current in the observed area,which exploits acoustic measurements like travel time.Specificly,acoustic tomography for current is a multidimensional problem which associated with ocean survey,acoustic propagation model and acoustic inverse problem.Firstly,the reciprocal transmission model is introduced.Based on traditional Least-Square method,we can solve the inverse problem using the data of transmission time between the receive-and-send transducers we put in the water.However,this method is suffered from perturbation from noise.In this paper,we present maximum entropy method to solve inverse problem based on wave theory in shallow water.To adopt maximum entroy method,firstly the signal trasmissin model and the maximum entropy theory should be conneted together.We introduce Radial Basis Function as the basis function to reconstruct the current field.We adopt Bellhop model to simulate the.signal transmission in the current and calculate the difference between two transducers.Among this procedure,peak patten match method is introduced in order to get precise delay difference between two signals we receive.Finally,input the differences of travel time into the model of maximum entropy,solve the equation under the restriction from the model,then we get the result.In this paper,we present a series of simulations ocean acoustic tomography based on Least Square method and Maximum Entropy method.Comparisons are shown between these two methods,which focus on accuracy.Finally,an ocean acoustic tomography software is developed according to the research above.