Welcome to the subject EKT 231 COMMUNICATION SYSTEM

LECTURERS 1. En. Rosnazri Bin Ali 2. Pn. Siti Rafidah Bt. Abdul rahim

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, Introduction to Communication System, Analog Modulation and Demodulation (e.g. Amplitude Modulation), Analog Modulation and Demodulation (e.g. Amplitude Modulation), Angle Modulation (Frequency Modulation and Phase Modulation), Angle Modulation (Frequency Modulation and Phase Modulation), Digital Modulation, Digital Modulation, Noise in Communication System, Transmission System and Transmission Lines. Noise in Communication System, Transmission System and Transmission Lines.

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

OBJECTIVES (Cont’d) To characterize frequency and phase modulated signals in the time domain and tone modulated signals in the frequency domain. 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 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 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 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. To enhance the students’ knowledge on transmission line those are used in communication system.

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

Assessment Final Exam = 50 % Final Exam = 50 % Coursework = 50 % Coursework = 50 % Test x2 = 15 % Test x2 = 15 % Labs= 30 % (lab work 20%, lab Labs= 30 % (lab work 20%, lab test 10%) test 10%) Assignments/quizzes = 5% Assignments/quizzes = 5%

CHAPTER 1 INTRODUCTION TO COMMUNICATION SYSTEM

Definitions Communications: Communications:  Transfer of information from one place to another.  Should be efficient, reliable, and secured. Communication system: Communication system:  components/subsystems act together to accomplish information transfer/exchange

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

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

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

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

Think! Have you ever pictured yourself living in a world without any communication system? Have you ever pictured yourself living in a world without any communication system?

Development and progress Communications between human beings Communications between human beings  Form of hand gestures and facial expressions  Verbal grunts and groans Long distance communications Long distance communications  Smoke signals  Light, mirror reflection  Telegraph  Telephone

Cont’d… Wireless radio signals Wireless radio signals  Spark-gap transmitter  Continuous carrier wave transmitter (with the invention of triode vacuum tubes)  Commercial radio broadcasting  Satellite communications  Mobile telephones

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

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

Vacuum tube The first transistor

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

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

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

Analog vs. Digital Analog Analog  Continuous Variation  Assume the total range of frequencies/time  All information is transmitted Digital Digital  Takes samples:  non continuous stream of on/off pulses  Translates to 1’s and 0’s

Analog vs. Digital Digital CS 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.

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

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

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

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

Signal Types

Conversions Between Signal Types Sampling Quantizing Encoding

Sound Recording System

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

Elements of Communication System(CS) W2-1

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

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

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

Elements of CS(cont’d) Receiver: Receiver:  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.  E.g. mixing, demodulation, decoding  Other functions performed: Amplification, filtering.  Transducer converts the electrical signal at its input into a form desired by the system used

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