The Research Of Digital Communication In Low Noise Testing System

This subject comes from the project of the low noise test of submarine by Dalian test&control institute .At the present developing status, for detecting and anti-detecting, the country with military great power in the world regards reducing submarine noise as the important tactics guideline of submarine latent. As main detecting measure, submarine noise is crucial factor of destroy submarine latent. In order to test and evaluate submarine' s noise characteristic, real submarine testing technique and quiet submarine design keeps the same pace development. With research of new low noise submarine and development of quiet submarine technology in our country, technique of low Signal-to-Noise submarine testing has become bottleneck of restricting submarine noise development. How to test and evaluat technique of quiet submarine is a main problem at present. Underwater testing system presently has not kept up with the development of military product. However, the digital communication technology applied to this system will enhance measure level and promote the development of national defence.The main task of the paper is to achieve data and power signal transmit and real-time display of the data, firstly, it expatiates on practical meaning of the system design and discusses the material method, then we select rs-485 bus standard as transmit form of data, and use coupling transformer to realize differential signal and power transmission of single line. Secondly, it analyzes the theory of rs-485 bus and indicates some problem which we ought to solve. At the same time, we design chief project according to system demand. At last, we achieve hardware connections and software programming. Hardware include collection card transmission module and application ofreceive module. The central processing unit of collection card is ADSP-2181 of AD company, its serial port and ADM1485 together accomplish communication function. The transmit module is the crucial part of the system. It solves the problem of modulate and demodulation of differential signal and achieve data and power signal communication in coaxial-cable. We also introduce usage of receive module. The module is the interface of hardware and software. Software includes control part and display part. The paper mainly accomplish the display software. At first, we describe programming surroundings, namely windows and programming software Delphi, and the communication protocol of display software and receive module. At last, we materially describe software interface according to module and multithreading. Experiment has proved that the system achieve the prospective aim.