EKT 231 COMMUNICATION SYSTEM LECTURER Pn Siti Rafidah

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EKT 231 COMMUNICATION SYSTEM LECTURER: Pn. Siti Rafidah Bt. Abdul Rahim 04 -9852441 /

EKT 231 COMMUNICATION SYSTEM LECTURER: Pn. Siti Rafidah Bt. Abdul Rahim 04 -9852441 / 012 -5075789 rafidah@kukum. edu. my PLV: Cik Diyya Hidayah 1

SYNOPSIS The aim of this subject is : to introduce the students with the

SYNOPSIS The aim of this subject is : to introduce the students with the basic principles and components of communications system. This subject will cover various topics such as: Introduction to Communication System, Analog Modulation and Demodulation (e. g. Amplitude Modulation), Angle Modulation (Frequency Modulation and Phase Modulation), Digital Modulation, Noise in Communication System, Transmission System and Transmission Lines. 2

OBJECTIVES To understand the basic components in a wire line and wireless communication system

OBJECTIVES To understand the basic components in a wire line and wireless communication system for analog and digital transmission. To emphasize on the importance of modulation and demodulation of analog signals along with associated system design issues. To introduce the student with the types of analogue and digital modulation techniques those are used in present telecommunication system. To characterize amplitude, double-sideband single sideband modulated waveforms in the time and the frequency domains. 3

OBJECTIVES (Cont’d) To characterize frequency and phase modulated signals in the time domain and

OBJECTIVES (Cont’d) To characterize frequency and phase modulated signals in the time domain and tone modulated signals in the frequency domain. To study the quantization process in a pulse code modulation system in terms of how it is created and how to minimize its effect. To study the characteristic of noise and its effect on the communications system. To study and analyze the modulated analog and digital signals performance in the presence of additive noise. To enhance the students’ knowledge on transmission line those are used in communication system. 4

References Wayne Tomasi, “ Electronic Communication Systems Fundamentals Through Advanced” 5 th Ed, Prentice

References Wayne Tomasi, “ Electronic Communication Systems Fundamentals Through Advanced” 5 th Ed, Prentice Hall, 2004. Paul Young, “Electronics Communications Techniques”, 5 th Edition, Prentice Hall, 2004. Mullet , “Basic Telecommunications: The Physical Layer”, Thomson Learning, 2003. 5

Assessment Final Exam = 50 % Coursework = 50 % Test x 2 =

Assessment Final Exam = 50 % Coursework = 50 % Test x 2 = 15 % Labs = 30 % (lab work 20%, lab test 10%) Assignments/quizzes = 5% 6

CHAPTER 1 INTRODUCTION TO COMMUNICATION SYSTEM 7

CHAPTER 1 INTRODUCTION TO COMMUNICATION SYSTEM 7

Definitions Communications: ØTransfer of information from one place to another. ØShould be efficient, reliable,

Definitions Communications: ØTransfer of information from one place to another. ØShould be efficient, reliable, and secured. Communication system: Øcomponents/subsystems act together to accomplish information transfer/exchange 8

Definitions (Cont’d) Electronic communication system Øtransmission, reception and processing of information between two or

Definitions (Cont’d) Electronic communication system Øtransmission, reception and processing of information between two or more locations using electronic circuits. Information source Øanalog/digital form 9

Information, message and signals Information ØThe commodity produced by the source for transfer to

Information, message and signals Information ØThe commodity produced by the source for transfer to some user at the destination. Message ØThe physical manifestation of information as produced by the information source. Signals ØA physical embodiment of information – voltage signal or current signal 10

Need For Communication Importance of communication: exchange of information between two parties separated in

Need For Communication Importance of communication: exchange of information between two parties separated in distances in a more faster and reliable way. 11

Information transfer system block diagram Information sources > Audio Processing > Video (modulator) >

Information transfer system block diagram Information sources > Audio Processing > Video (modulator) > Data (with their respective transducers) Reproduced information Audio Video Data Transducers Transmitter Transmission medium Receiver / Processing (demodulator) 12

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Development and progress Communications between human beings ØForm of hand gestures and facial expressions

Development and progress Communications between human beings ØForm of hand gestures and facial expressions ØVerbal grunts and groans Long distance communications ØSmoke signals ØLight, mirror reflection ØTelegraph ØTelephone 14

Cont’d… Wireless radio signals ØSpark-gap transmitter ØContinuous carrier wave transmitter (with the invention of

Cont’d… Wireless radio signals ØSpark-gap transmitter ØContinuous carrier wave transmitter (with the invention of triode vacuum tubes) ØCommercial radio broadcasting ØSatellite communications ØMobile telephones 15

Early wireless telegraph station (using spark-gap transmitter) Transmitter Receiver 16

Early wireless telegraph station (using spark-gap transmitter) Transmitter Receiver 16

Notice that the person is wearing a belt that full with vacuum tubes !

Notice that the person is wearing a belt that full with vacuum tubes ! 17

Vacuum tube The first transistor 18

Vacuum tube The first transistor 18

Brief History in Communication Year 1844 1862 1876 1888 1895 1904 1906 Events Telegraph

Brief History in Communication Year 1844 1862 1876 1888 1895 1904 1906 Events Telegraph – Samuel B. Morse Prediction of electromagnetic waves propagation through a vacuum – James Clerk Maxwell Telephone – Alexander Graham Bell Proved of EM waves existence – Heinrich Hertz Wireless telegraph – G. Marconi Invention of diode vacuum tube – John Fleming Invention of triode vacuum tube – Lee de Forest 19

cont’d…. Year 1906 1920 1923 1933 1941 1948 Events Amplitude modulation (AM) – Reginald

cont’d…. Year 1906 1920 1923 1933 1941 1948 Events Amplitude modulation (AM) – Reginald Fessenden 1 st radio broadcast (AM, in US) Television - Vladimir Zworykin Frequency modulation (FM) – Edwin H. Armstrong FM radio broadcast (US) Invention of transistor 20

cont’d…. 1957 1966 1972 1989 First satellite (Sputnik, Russia) Optical links using laser and

cont’d…. 1957 1966 1972 1989 First satellite (Sputnik, Russia) Optical links using laser and fiber optics Cellular Telephone Internet 21

Analog vs. Digital Analog ØContinuous Variation ØAssume the total range of frequencies/time ØAll information

Analog vs. Digital Analog ØContinuous Variation ØAssume the total range of frequencies/time ØAll information is transmitted Digital ØTakes samples: non continuous stream of on/off pulses ØTranslates to 1’s and 0’s § 22

Analog vs. Digital CS Advantages: -Privacy preserved(data encrypted) -Can merge different data -error correction

Analog vs. Digital CS Advantages: -Privacy preserved(data encrypted) -Can merge different data -error correction - high immunity to noise Disadvantages: -synchronization problem is relatively difficult Analog CS Disadvantages: -No privacy preserved -Cannot merge different data -No error correction capability - Susceptible to noise Advantages: -synchronization problem is relatively easier. 23

Basic Requirements of Communication System Rate of information transfer: Øhow fast the information can

Basic Requirements of Communication System Rate of information transfer: Øhow fast the information can be transferred Purity of signal received: Øwhether the signal received is the same as the signal being transmit Simplicity of the system Øthe simpler the system, the better Reliability 24

Trade-off between analog and digital modulations Analog modulation Wide bandwidth medium Simple modulation and

Trade-off between analog and digital modulations Analog modulation Wide bandwidth medium Simple modulation and hardware Digital modulation Complex modulation and hardware Simple demodulation and hardware Narrow bandwidth medium Complex demodulation and hardware 25

Signals and Systems Defined A signal is any physical phenomenon which conveys information Systems

Signals and Systems Defined A signal is any physical phenomenon which conveys information Systems respond to signals and produce new signals Excitation signals are applied at system inputs and response signals are produced at system outputs 26

A Communication System as a System Example A communication system has an information signal

A Communication System as a System Example A communication system has an information signal plus noise signals This is an example of a system that consists of an interconnection of smaller systems 27

Signal Types 28

Signal Types 28

Conversions Between Signal Types Sampling Quantizing Encoding 29

Conversions Between Signal Types Sampling Quantizing Encoding 29

Sound Recording System 30

Sound Recording System 30

Recorded Sound as a Signal Example “s” “i” “gn” “al” 31

Recorded Sound as a Signal Example “s” “i” “gn” “al” 31

W 2 -1 Elements of Communication System(CS) 32

W 2 -1 Elements of Communication System(CS) 32

Elements of CS(cont’d) Information Ø The communication system exists to convey a message. Ø

Elements of CS(cont’d) Information Ø The communication system exists to convey a message. Ø Message comes from information source Ø Information forms - audio, video, text or data 33

Elements of CS(cont’d) Transmitter: Ø Processes input signal to produce a transmitted signal that

Elements of CS(cont’d) Transmitter: Ø Processes input signal to produce a transmitted signal that suited the characteristic of transmission channel. Ø E. g. modulation, coding, mixing, translate Ø Other functions performed - Amplification, filtering, antenna Ø Message converted to into electrical signals by transducers Ø E. g. speech waves are converted to voltage variation by a microphone 34

Elements of CS(cont’d) Channel (transmission media): Ø a medium that bridges the distance from

Elements of CS(cont’d) Channel (transmission media): Ø a medium that bridges the distance from source to destination. Eg: Atmosphere (free space), wires, coaxial cable, fiber optics, waveguide Ø signals undergoes degradation from noise , interference and distortion 35

Elements of CS(cont’d) Receiver: Ø to recover the message signal contained in the received

Elements of CS(cont’d) Receiver: Ø to recover the message signal contained in the received signal from the output of the channel, and convert it to a form suitable for the output transducer. Ø E. g. mixing, demodulation, decoding Ø Other functions performed: Amplification, filtering. Ø Transducer converts the electrical signal at its input into a form desired by the system used 36

Various forms of communication system Broadcast: radio and television Mobile communications Fixed communication system-

Various forms of communication system Broadcast: radio and television Mobile communications Fixed communication system- land line Data communication-internet 37