Method for measuring submarine density and sound velocity based on multi-path reflection theory

Abstract

The invention provides a method for measuring submarine density and sound velocity based on multi-path reflection theory; based on plane wave reflection theory and snell law, the method comprises: extablishing equations with submarine reflection coefficients of multiple paths, measuring the time of arrival, the nearby reflection angle and energy at seabed of each path by equipment such as a vertical array and a sound source so as to finally obtain submarine density and sound velocity; the measured submarine density and sound velocity can be used to solve the positioning problem of passive objects in an unknown condition of submarine environment in shallow sea. The beneficial effects of the invention are that: the method uses obliquely incident sound wave of a sound source; the reflection wave energy is large; the emitting sound source is not limited by high power or narrow directivity; the method can measure submarine density and sound velocity independently; although earth sound parameters of each layer of a multilayer submarine medium can not be measured, equivalent density and sound velocity under a submarine semi-infinite space model can be measured; and the method has the advantages of a simple and practical experiment platform, low price, low computational complexity and the like.

Description

technical field [0001] The invention relates to the field of ocean bottom geoacoustic parameter measurement and inversion based on acoustic methods, and mainly relates to a method for measuring bottom density and sound velocity based on multipath reflection theory. Background technique [0002] In shallow ocean acoustics, due to the frequent interaction of acoustic energy with the seabed and sea surface, knowledge of some submarine geoacoustic parameters, such as seabed density, sound velocity, and attenuation coefficient, is useful in predicting the performance of sonar systems in shallow sea environments (especially some model-based processing methods ) plays an important role. At present, there are two main types of ocean bottom geoacoustic parameter measurement and inversion methods based on acoustic methods. One is to measure the acoustic impedance (the product of density and sound velocity) of the seafloor substrate based on the reflection and transmission theory of p...

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Problems solved by technology

The disadvantage of this method is that due to the vertical incidence of sound waves, most of the sound energy can be transmitted into the sediment layer, so the reflected energy is small, and a high-power, narrow-direction emission sound source is required, especially when the frequency is low, the cost of the sound source Expensive and bulky; in addition, this method can only measure the acoustic impedance of the seafloor substrate and cannot independently measure density and sound velocity

The second type of method is currently the most commonly used method is matching field inversion. The disadvantage of this method is that it has a large amount of calculation. It often combines nonlinear algorithms such as simulated annealing and genetic factors to complete the search of environmental parameters; in addition, in order to be more accurate Earth inversion of geoacoustic parameters, this type of method often needs to measure sound propagation data at multiple receiving distances, which is expensive

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