电子科技大学：《数字通信基础 Digital Communications》课程教学资源（课件讲稿，图片版）Chapter 01 Introduction 1.1 Exampls

Chapter 1 Introduction -by Prof.XIAOFENG LI SICE,UESTC UESTC-Introduction Prof李晓峰 1

Examples of communication Sys Diagram and elements of Comm.Sys Digital Comm.Sys. Channels and their characteristics UESTC-Introduction Prof李晓峰 2

Examples of communication Examples of communications: 1.Mobile phones 2.Telephone 3.Computer network Related words: 1.Radio sets,TV sets,Satellite 2.Post office,letters 3.Speech Transmission of information in ELECTRONIC/ELECTRICAL ways UESTC-Introduction Prof李晓峰 3

Examples of communication Mobile phone=Telephone+SMS+ Radio+TV+Internet+... 圈 UESTC-Introduction Prof李晓峰 4

Examples of communication Mobile phone=Telephone+SMS+ 圈 Radio+TV+Internet+... SMS(QQ,WeChat)=Short Message Sys =Telegraphy Telegraphy:oldest communication sys UESTC-Introduction Prof李晓峰 5

Examples of communication Mobile phone=Telephone+SMS+ 圈 Radio+TV+Internet+... SMS(QQ,WeChat)=Short Message Sys =Telegraphy Telegraphy:oldest communication sys Morse code (1837)uses DASH and DOT(0/1),representing long and short pulses respectively,to code a letter in a text. 議 UESTC-Introduction Prof李晓峰 6

Examples of communication Mobile phone=Telephone+SMS+ 圈 Radio+TV+Internet+... SMS(QQ,WeChat)=Short Message Sys =Telegraphy Telegraphy:oldest communication sys The idea of using 0 and 1(binary digits,bits)to code information symbols and then transmit the sequence of bits is the standard way of modern communication systems. UESTC-Introduction Prof李晓峰 7

Examples of communication Mobile phone=Telephone+SMS+ Radio+TV+Internet+... Telephony (1870s):the most important analog communication system Alexander Graham Bell 图 Carbon microphone,speaker,triode amplifier,automatic switching,networks,PCM and digital techniques,fiber optical cables are important advances in its development. UESTC-Introduction Prof李晓峰 8

Examples of communication Mobile phone=Telephone+SMS+ Radio+TV+Internet+... Wireless communications The theory of electromagnetic waves(radiation) E=号 V.B=0 was formulated by James C.Maxwell in 1864. VxE=-那 Confirmed by Heinrich Hertz in1887. xB=+》 ■ Detection of radio waves was firstly done by Coherer by Oliver Lodge in 1894. （ G.Marconi patented a wireless telegraphy system in 1897. UESTC-Introduction Prof李晓峰 9

Examples of communication Mobile phone=Telephone+SMS+ Radio+TV+Internet+... Wireless communications Radio broadcasting were important application in old days.AM radio was initiated in Pittsburgh in 1920.Then Edwin Armstrong invented super- heterodyne receiver and demonstrated FM radio. Conceptual system of TV appeared in 1929. UESTC-Introduction Prof李晓峰 10