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Komdat Tugas #01 08-03-2014

Petunjuk:1. Silakan diskusi dan bekerja sama dalam kelompok.2. Setiap kelompok terdiri dari 2 mhs (silakan pilih sendiri pasangan anda).3. Diskusi dg kelompok lain boleh, tapi pastikan jangan copy-paste, tidak ada toleransi plagiat.4. Tuliskan NIM, Nama, dan Tanda Tangan kedua-dua anggota kelompok.5. Hasil pekerjaan diterima paling lambat hari ini Sabtu 08-03-2014 pukul 21.00 WIB.

Tugas berupa belajar bersama dan membuat ringkasan terhadap materi di bawah.Ringkasan dibuat dalam 1 halaman A4 (kuarto) saja, font/ukuran huruf bebas.• Boleh ketik komputer• Boleh tulis tangan kemudian scan (dengan format PDF) • Boleh tulis tangan kemudian foto dg cameraKemudian kirim email ke sunargm@yahoo.com

Catatan: Ringkasan mewakili semua materi, tapi bukan berarti semua materi ditulis dalam ringkasan.Buat serapi dan sejelas mungkin file yang dikirim, baik ketik komputer, tulis tangan, scan, atau foto camera.

Selamat belajar

Chapter 1

Introduction to Data Communications

TerminologyWhen we communicate, we are sharing information.

Data refers to information presented in whatever form is agreed by the parties creating and using the data.

Data communications is the exchange of data between two devices via transmission medium.

TerminologyCommunication based on distance.

1. Local communication usually occurs face-to-face.

2. Remote communication takes place over distance.

Telecommunication (includes telephony, telegraphy, television)means communication at a distance.

Fundamental characteristicsThe effectiveness of data comm system depends on three fundamental characteristics;

1. DELIVERY. The system must deliver data to the correct destination. (addressing, routing)

2. ACCURACY. The system must deliver data accurately. (error detection and correction)

3. TIMELINES. The system must deliver data in a timely manner. (delay)

ContentData Comm ComponentsData Representation (text, number, image, audio, video) Direction of Data Flow (simplex, half-duplex, full-duplex) Transmission Mode

- Parallel- Serial (synchronous, asynchronous)

Transmission Media Speed

Data Comm ComponentsData Comm system has 5 components;

1. MESSAGE: the information (data) to be communicated. It can consist of text, numbers, images, sound, video (or any

combinations).

2. SENDER: the device that send the data message. It can be a computer, workstation, telephone handset, video camera, and so on. 3. RECEIVER: the device that receives the message. It can be a computer, workstation, telephone handset, video camera, and so on. 4. TRANSMISSION MEDIUM: the physical path by which a message travels from sender to receiver. It could be twisted-pair wire, coaxial cable, fiber-optic cable, radio waves.

Data Comm ComponentsData Comm system has 5 components;

5. PROTOCOL: set of rules that governs data comm. It represent agreement between comm devices.

Without protocol, two devices may be connected but can not communication.

Protocol ~ Language

Saya hanya boleh cakap dan paham Bahasa Melayu

iki sakjane ono opo tho, kok ora mudheng blaz

connected but can not communicate

ContentData Comm ComponentsData Representation (text, number, image, audio, video) Direction of Data Flow (simplex, half-duplex, full-duplex) Transmission Mode

- Parallel- Serial (synchronous, asynchronous)

Transmission Media Speed

Data RepresentationInformation today comes in different forms, such as;

1. TEXT

2. NUMBERS

3. IMAGES

4. AUDIO

5. VIDEO

1. TextIn data comm, text is represented as a bit pattern,

a sequence of bits (0s and 1s).

Different sets of bit patterns have been designed to represents text symbols.

Each set is called code.Process of representing symbols is called coding.

Code : 1. ASCII ( 7 bits for each symbol)2. Extended ASCII ( 8 bits for each symbol)3. EBCDIC ( 8 bits for each symbol)4. Unicode (16 bits for each symbol)5. ISO (32 bits for each symbol)

ASCII American Standard Code for Information Interchange

Developed by ANSI (American National Standards Institute).This code uses 7 bits for each symbol.This means 128 = 27 different symbols can be defined.

05/03/2023 14

ASCII Code

Please encode “I & You” using ASCII Code

ASCII American Standard Code for Information Interchange

ASCII uses 7 bits for each symbol, this means 128 = 27 different symbols can be defined.Extended ASCII uses 8 bits for each symbol, this means ……… different symbols can be defined

EBCDICExtended Binary Coded Decimal Interchange Code

Developed by IBM (International Bussiness Machines Corporation).This code uses 8 bit for each symbolThis means 256 = 28 different symbols can be defined.

EBCDIC

Pleasea encode “I & You” using EBCDIC Code

Code (still exist ?): 1. Baudot2. Morse

Baudot

Developed by Emil BaudotThis code uses 5 bit for each symbol This means 32 = 25 different symbols can be defined.

Baudot Code

Baudot

Morse CodeCombination of dot and dash.

2. NumbersNumbers are also represented by using bit patterns.

However, a code such as ASCII is not used to represent numbers, the number is directly converted to a binary number.

The reason is to simplify mathematical operations on numbers.

All the numbering systems examined here are positional, meaning that the position of a symbol in relation to other symbols determines its value.

Within a number, each symbol is called a digit: - Decimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)- Binary digit = bit (0, 1)- Octal digit (0, 1, 2, 3, 4, 5, 6, 7)- Hexadecimal digit (0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F)

3. ImagesNumbers today are also represented by bit patterns.

However, the mechanism is different.

An image is divided into a matrix of pixels (picture elements), where each pixel is a small dot. Then each pixel assigned a bit pattern

Size of pixel depends on resolution. Higher resolution is need more memory.

Size and value of the pattern depend on the image;- Black, white (pure) 0, 1- Black, dark gray, light gray, white 00, 01, 10, 11- Color RGB @ 8 bits

4. AudioAudio is representation of sound.

Audio is by nature different from text, numbers, or images. It is continuous, not discrete.

We can change audio to digital or analog signal.

5. Video

Video can be produced either as a continuous entity (e.g., by TV camera), or it can be combination of images (each a discrete entity, arrange to convey the idea of motion).

We can change video to digital or analog signal.

ContentData Comm ComponentsData Representation (text, number, image, audio, video)Direction of Data Flow (simplex, half-duplex, full-duplex) Transmission Mode

- Parallel- Serial (synchronous, asynchronous)

Transmission Media Speed

Direction of Data Flow

Communication between two devices can be ; - Simplex- Half-duplex- Full-duplex

Simplex: One direction only Simplex

host computer terminal

first one w ay....

terminal

...then the other

Half-DuplexBoth directions,but only one direction at a time

send and receive both directions at onceFull-Duplex

ContentData Comm ComponentsData Representation (text, number, image, audio, video)Direction of Data Flow (simplex, half-duplex, full-duplex) Transmission Mode

- Parallel- Serial (synchronous, asynchronous)

Transmission Media Speed

05/03/2023 TJ 2013 - Komunikasi Data 32

Transmission mode

R

ecei

ver r

ecei

ved

Each bit has it’s own piece of wire along which it travels

Often used to send data to a printer

1. Parallel Transmission

Sender transmitted

All bits are sent simultaneously

10011001

Sender transmitted

Data is transmitted on a single channel, one bit at a time one after another

- Much faster than parallel because of way bits processed (e.g. USB and SATA drives)

Receiver received

2. Serial Transmission

101 0 0 1 1 0

2a. Synchronous

Bit stream is combined into longer block data which may contain multiple bytes.Each byte without a gap between each other.Receiver responsible to separate the block data into bytes for decoding purposes.

all data sent at once

Synchronous

SYN Characters

Several bits add into block of data.Purposes;

To ensure the line is active as long as transmission time.

To ensure status of sender and receiver are active

To maintain rate of transmission.

• Uses start/stop bits for each byte• Allow gap between data unit

2b. Asynchronous

Asynchronous

Synchronous• Higher data rate• Efficient of control bit

Asynchronous • Most common type of serial data transfer• Allows packet switching• Allows sharing of bandwidth (i.e. talk on

phone while another person is using internet)

ContentData Comm Components Data Representation (text, number, image, audio, video) Direction of Data Flow (simplex, half-duplex, full-duplex) Transmission Mode

- Parallel- Serial (synchronous, asynchronous)

Transmission Media

Transmission MediaTwisted pair – telephone cableCoaxial cable –thick black cable used for higher bandwidth communications than twisted pair Fibre optic – data transferred through pulses of light. Extremely fast. Non cable methods such as satellite, microwave, wireless and bluetooth.

Bandwidth:The amount of data which can be transmitted on a medium over a fixed amount of time (second). It is measured on Bits per Second or Baud

Bits per Second (bps): A measure of transmission speed. The number of bits (0 or 1) which can be transmitted in a second

Baud Rate: Is a measure of how fast a change of state occurs (i.e. a change from 0 to 1)

Components

ISDN Integrated Services Digital NetworkPrivate Branch Exchanges PBXs, Key SystemsTelcos AT&T, Bell Telephone, Sprint, TelusDataPac & DataRoute Packet switching and analog switching WAN protocolsCell Relay Digital packet switching WAN protocol Frame Relay Digital packet switching WAN protocol X.25 Analog packet switching WAN protocol ATM Asynchronous Transfer Mode WAN protocol World Wide Web Hypertext-based multimedia system ADSL Asymmetrical Digital Subscriber Line

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Analog and Digital Transmissions

Graphical Symbols

Circles Network Operating SystemsSquares Communication & cabling protocols (OSI Transport to Physical Layer)Storm Clouds Telecommunications media or Information Providers that connect to the InternetMachine symbol Network "linker" can be a bridge, router, brouter or gatewayJagged haphazard dotted line - the Internet