Research On Shallow Water Text/Image Communication

With the development of our country in all aspects, underwater communication is getting more and more important. It affects different fields including national politics, economy, military, science development, and so on. Our country is in possession of abundant ocean resources, a strong navy is needed for protecting national rights and interests of our marginal sea. So it's of important significance to make further research on underwater communication.Underwater communication covers text, voice, image, data communication, and others. This thesis focuses on the topic of text and image communication. But in general, the system this thesis discussed can be used in any kind of digital signal transfer.The underwater acoustic signal is transferred in the underwater acoustic channel. Study of characteristics of underwater acoustic channel can give significant guidance to the research of underwater communication. Based on former research background of project team and in reference to data documents, this thesis illustrates the characteristics of underwater acoustic channel and its influence on the transferring of underwater acoustic signal and relative solutions. It is also introduced in this thesis the most commonly used signal processing strategies in underwater communication and the platform to realize it: DSP (Digital Signal Processor).In the last part of this thesis, a real underwater text / image communication system based on DSP is introduced, and the experiment results gathered in the lab and in Xiamen port are given. The results present, this system can successfully transfer the text, text of image type, image, compressed image; text information in the image type can be easily recognized even with a high error rate, the same to the image transfer. The compressed image can be decoded correctly when the error rate is lower than 5%.There are four main chapters in this thesis:Chapter 1: Exordium; the significance of underwater communication research...