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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 [email protected]
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
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