A Study On Classification Of Surficial Shallow-Water Sediments Based On Acoustical Phase-Plane Method

Most parts of ocean bottoms cover a layer of soft sediment, whose properties are full of important signification to military and civil applications. Therefore, the study on the sediment types of continental shelf and deep oceans is always a classical and interesting issue, and it is also an important content of the new survey to our country's territorial resources.The conventional direct sampling method can obtain the precise information of types of ocean sediments, but it has some shortcoming as follows: 1.It's inefficient and uneconomical. 2. It uses the discrete sampling that cannot acquire continuous data. 3. The samples should be easily disturbed so that it's hard to get the accuracy result. Therefore it is being replaced by the indirect methods such as acoustic technique. Acoustic remote sensing is an efficient and economic technique, which can get the data continuously and sufficiently. Combining direct samplings, it offers a rapid and stable method to the classification and recognition of ocean sediments.In this thesis, a study on the classification of surficial shallow-water sediments off central & northern Yellow Sea by statistical feature of first moment on phase plane is made,dealing with the data of experiment in this area.When using such past singal processing as empirical mode distribution,karhunen-loeve transform methods to deal with narrow-band signal,we can hardly extract parameter to classify,and analyzed the reason why these methods can't be used to deal with this problem.At the same time,it put forward a statistical eigenvalue extraction method based on phase points of the track on phase plane to classify ocean sediments. Signal constitution of narrow-band echo sound has been analyzed to dealed with the reflected and scattered components separately. Contrast between scattered component and incident angle has been made ,and drawn a conclusion which does not depend on the intercepted length of echo sound signal.By computation of real data on five ocean spots,they can clearly be classified to three sediment types:A,B and H2 spots are fine sand sediment,C spot is sand sediment and H3 spot is mud sediment.The result is accord with geological sample and sediment chart,so this method can be applied on sediment classification of narrow-band pulse echo sound signal.