Research On Speech Comperssion And Recognition Of Wireless Through-the-earth Communication

This project comes from "Shanxi Natural Science Foundation of China(2013011019-2): for mine disaster relief through the formation of radio channel research".As a country full of coal resource,the coal mining of China has been at the forefront of the world.However,coal mine accidents have occurred very often,making research and development of wireless communication system can be applied with the coal mine is increasingly becoming an urgent need.And wireless communication is different from wired communication,or wireless communication in space,because of the particularity that the signal needs to through the earth,making its communication channel resources are very tense.Research progress on wireless through-the-earth(TTE)communication is slow for such reasons.In this paper,based on those principle of mine wireless TTE communication system and the development of communication technology,a low coding rate MELP algorithm is proposed for speech coding before transmission and saving channel resources.This paper also proposes two speechcoding schemes with lower coding rate based on MELP.The main work of this paper is:(1)This paper discusses the principle of wireless communication system and analyzes the characteristics of communication channel,and obtains the working frequency range of voice signal transmission in wireless TTH communication system.And the interference types in wireless TTH communication are analyzed,as well as the ways to reduce the impact of interference are also proposed,for the choice of speech coding program to do the guidance.(2)Based on the relevant theoretical research,this paper proposes to apply MELP to wireless TTH communication.In order to establish MELP vocoder,the basis technology of speech generation model and coding algorithm is analyzed,and some algorithm parameters are specified.(3)A detailed MELP coding algorithm is designed and analyzed,and the simulation parameters of the coding algorithm are worked out.(4)The application of MELP speech coding algorithm in wireless TTH communication is verified.Based on this simulation,two lower rate coding schemes are proposed: 2.044kb/s,1.8kb/s.The two proposed improvements are based on the reduction of the number of bits per frame and the reduction of frame length per frame.It is concluded that it is feasible to apply MELP speech coding to mine wireless TTH communication.The synthesized speech quality of the two2.044kb/s and 1.8kb/s speech coding scheme based on the MELP is reduced,butit can be recognized by human subject.The two 2.044kb/s and 1.8kb/s speech coding scheme can be applied to wireless TTH communication according to the actual situation as an alternative to speech coding.The research of this paper provides some theoretical support for the selection of speech coding scheme for wireless TTH communication system,which has certain feasibility and practicability.