EC301 : Computer Network Fundamental

Noted prepared by:Pn. Wan Fazlini Idayu binti Wan

Fakari

Chapter 3.0 : Data Transmission & Networking Media

CLO 3: you should be able to select addressing scheme of TCP/IP in Local Area Network (LAN) properly using network configuration tool. (C4) CLO 4: you should be able to create a simple network connection using Wireless Local Area Network (WLAN) in accordance to IEEE 802.11 protocols. (P7)note: C4 = analysis, P7=origination

• Chapter 3 will appear in:-– Lab (2)– Quiz (3)

3.1 Basics of Data Transmission

Data transmission• Data transmission is the physical transfer of data over a point-to-point or

point-to-multipoint communication channel.

• Examples of such channels are copper wires, optical fibres, wireless communication channels, and storage media.

• The data is represented as an electro-magnetic signal, such as an

electrical voltage, radiowave, microwave or infra-red signal. • While analog communications is the transfer of continuously varying

information signal, digital communications is the transfer of discrete messages.

• The passband modulation and corresponding demodulation is carried out by

modem equipment.

Basic Data Transmission Concepts

a) Analog and digital signaling b) Data modulation c) Simple, half-duplex, and full-duplex transmission d) Multiplexing e) Point-to point transmission f) Broadcast transmissiong) Throughput h) Bandwidth

3.1.1

Electronic signal that varies directly with time changes for an infinite range of time. (Isyarat elektronik yang berubah secara terus dengan perubahan masa untuk satu julat masa tak terhingga)

Your speech, a siren, and live music are all examples of analog waves. (percakapan, siren, dan muzik merupakan contoh gelombang analog)

using of continuous signals to represent information/data. (menggunakan isyarat selanjar untuk mewakili maklumat/data)

An analog signal is characterized by four fundamental properties: amplitude, frequency, wavelength, and phase. (Sebuah isyarat analog dicirikan oleh empat sifat: amplitud, frekuensi, panjang gelombang, dan fasa)

Analog Signaling

amplitude is a measure of its strength at any given point in time. (amplitud adalah ukuran kekuatan pada setiap titik masa yang tertentu)

frequency is a number of wave cycles in one second (f=1/t). t=The times of wave’s amplitude cycles from its starting point, through its highest amplitude and its lowest amplitude. (merupakan jumlah kitaran gelombang di dalam satu saat. t=masa bagi gelombang melengkapkan 1 kitaran dari titik awal, melalui amplitud tertinggi dan terendah)

Wavelength is a distance between corresponding points on a wave’s cycle

phase refers to the change or movement of the signal in the form of angle. (Kadar perubahan atau pergerakan bagi isyarat dlm btk sudut)

Analog Signaling…Cont…

Analog Signaling…Cont…

amplitude frequency wavelength

phase

Digital signals are composed of pulses of precise, positive voltages and zero voltages. (isyarat digital terdiri dari pulsa yang tepat, voltan positif dan sifar)

A pulse of positive voltage represents a 1. A pulse of zero voltage represents a 0. (Sebuah pulsa voltan positif mewakili 1 dan pulsa voltan sifar mewakili 0)

Every pulse in the digital signal is called a binary digit, or bit. (Setiap pulsa pada isyarat digital disebut sebagai angka binari, atau bit)

A bit can have only one of two possible values: 1 or 0. Eight bits together form a byte. (bit hanya boleh mempunyai satu daripada dua nilai yang mungkin: 1 atau 0. Lapan bit membentuk satu bait)

Digital Signaling

using of discrete signals to represent information/data. (menggunakan isyarat diskret untuk mewakili maklumat/data)

Number, letters or icons are all examples of digital signal. (Nombor, huruf atau ikon merupakan contoh isyarat digital)

Advantage:– more reliable than analog transmission– noise affects digital transmission less severely

Digital Signaling…Cont

Digital Signaling…Cont…

Differences between analog & Digital

• Analog signals are continuous where digital signals are discrete

• TV, some telephones, and tape recorders all use analog signals while the digital signal is numbers, letters or icons

Criteria for Analog and Digital Signal

Analog Signal: Digital Signal:

1. Analog signal are continuous.2. Analog signal is continuously

variable.3. The primary disadvantage of an

analog signal is noise.4. Sound waves are a continuous

wave and as such are analog in the real world.

5. Analog signal required lesser bandwidth capacity than digital capacity.

1. Digital signal is discrete.2. Digital signal are based on 0's and

1's.3. Noise is much easier to filter out

of a digital signal.4. Most computers used such as the

PC work using digital signals.5. Digital signal required greater

bandwidth capacity than analog signals.

The data signals issued by your computer must be converted into analog form before they get to the media transmission.

They must be converted back into digital form when they arrive at the ISP’s access server.

A modem (modulator/demodulator) accomplishes this translation.

Modulates digital signals into analog signals at the transmitting end, then demodulates analog signals into digital signals at the receiving end.

Data Modulation

Is a technology used to modify analog signals to make them suitable for carrying data over a communication media. (teknologi yang digunakan untuk menukar isyarat analog bagi membolehkannya membawa data melalui media komunikasi)

In modulation, a simple wave, called a carrier wave, is combined with another analog signal to produce a unique signal that gets transmitted from one node to another. (Dalam modulasi, gelombang yang disebut gelombang pembawa, digabungkan dengan isyarat analog lain untuk menghasilkan isyarat yang unik yang akan dihantar dari satu node ke yang lain)

The carrier wave has preset properties (including frequency, amplitude, and phase)

Data Modulation

Its purpose is to help convey information; in other words, it is only a messenger.

Another signal, known as the information wave (data wave), is added to the carrier wave.

When the information wave is added, it modifies one property of the carrier wave (for example, the frequency, amplitude, or phase).

Data Modulation…Cont…

The result is a new, blended signal that contains properties of both the carrier wave and added data.

When the signal reaches its destination, the receiver separates the data from the carrier wave.

Data Modulation…Cont…

Data Modulation…Cont…

Data Modulation…Analog…

Data Modulation…Digital…

Simplex signals may travel in only one direction sometimes called one-way, or unidirectional,

communication. Exp: Radio

Transmission Direction Mode

Half-Duplex signals may travel in both directions over a

medium but in only one direction at a time. Exp: walkie-talkie

Transmission Direction Mode…Cont…

Full-Duplex signals are free to travel in both directions over a

medium simultaneously also be called bidirectional transmission or,

sometimes, simply duplex. Exp: telephone

Transmission Direction Mode…Cont…

A form of transmission that allows multiple signals to travel simultaneously over one medium. (Satu bentuk penghantarn yang membolehkan beberapa isyarat dihantar serentak melalui satu medium)

Used to increase the amount of data that can be transmitted in a given time span. (digunakan untuk meningkatkan jumlah data yang boleh dihantar dalam jangka waktu tertentu)

A device that can combine many signals on a channel called multiplexer (mux). (Sebuah peranti yang boleh menggabungkan beberapa isyarat pada saluran disebut multiplexer (Mux))

Demultiplexer (demux) separates the combined signals and regenerates them in their original form. (Demultiplexer (demux) memisahkan gabungan isyarat dan mengembalikannya kepada bentuk asal)

Multiplexing

Multiplexing…Cont…

Computer

Computer

Computer

M

U

X

Computer

Computer

Computer

DEMUX

Multiplexing…Cont…

Multiplexing…Cont…

MULTIPLEXING

Frequency-Division Multiplexing

(FDM)

Wavelength-DivisionMultiplexing

(WDM)

Time-DivisionMultiplexing

(TDM)

Frequency-Division Multiplexing (FDM) FDM is an analog technique.

The signal was modulated by n separate modulator's into n different carrier frequencies.

Multiplexing…Cont…

Multiplexing…Cont…

Computer

Computer

Computer

M

U

X

Computer

Computer

Computer

DEMUX

Channel 1

Channel 2

Channel 3

Frequency-Division Multiplexing (FDM)

Time-Division Multiplexing (TDM) TDM is a digital technique.

Can be used when loading/capacity of data rates for media transmission is greater.

Multiplexing…Cont…

Multiplexing…Cont…

Computer

Computer

Computer

M

U

X

Computer

Computer

Computer

DEMUX

3 2 1

Time-Division Multiplexing (TDM)

Wavelength-Division Multiplexing (WDM) Is equivalent with FDM

Is a technology used with fiber-optic cable.

WDM enables one fiber-optic connection to carry multiple light signals simultaneously.

Multiplexing…Cont…

Multiplexing…Cont…

Cahaya berbilang

Cahaya tunggal

Wavelength-Division Multiplexing (WDM)

Point-to-point– When a data transmission involves only one transmitter

and one receiver

Broadcast– Transmission involves one transmitter and multiple

receivers.

Relationships Between Nodes

Relationships Between Nodes

Throughput– the measure of how much data is transmitted during a

given period of time

Bandwidth– measure of the difference between the highest and lowest

frequencies that a medium can transmit.

Relationships Between Nodes

Common Transmission Flaws Affecting Data Signals

a. Noise - any undesired electrical disturbance in a circuit, degrading the useful information in a signal

b. Attenuation - the loss of energy suffered by radiation as it passes through matter, esp as a result of absorption or scattering

c. Latency

3.1.2

noise is any undesirable influence that may degrade or distort a signal. (hingar ialah pengaruh yang tidak diingini yang boleh mengurangkan atau menukar isyarat)

A common source of noise is EMI (electromagnetic interference), or waves that emanate from electrical devices or cables carrying electricity. (Sumber umum bagi hingar adalah EMI (gangguan elektromagnet), atau gelombang yang berasal dari peranti elektrik atau kabel pembawa elektrik)

One type of EMI is RFI (radiofrequency interference), or electromagnetic interference caused by radiowaves. (Salah satu jenis EMI adalah RFI (gangguan frekuensi radio), atau gangguan elektromagnet yang disebabkan oleh gelombang radio)

Noise

Strong broadcast signals from radio or TV towers can generate RFI. (kekuatan isyarat broadcast dari radio atau TV dapat menghasilkan RFI)

When EMI noise affects analog signals, this distortion can result in the incorrect transmission of data, just as if static prevented you from hearing a radio station broadcast. (Ketika hingar EMI mempengaruhi isyarat analog, ia akan menghasilkan penghantaran data yang salah)

Noise

Crosstalk– occurs when a signal traveling on one wire or cable

infringes on the signal traveling over an adjacent wire or cable. (terjadi apabila isyarat yang melalui satu wayar atau kabel melanggar/mempengaruhi isyarat yang melalui wayar atau kabel yang berdekatan)

Noise

Wires affected by crosstalk

Cable

Wire transmitting signal

Crosstalk

The strength of a signal falls off with distance over any transmission medium. (kekuatan signal berkurangan disebabkan oleh jarak sesuatu media penghantaran)

Problems are dealt by the use of amplifiers or repeaters. (Masalah ditangani dengan menggunakan amplifier atau repeater)

A device that regenerates a analog signal is called a amplifier. Analog signals pass through an amplifier, an electronic device that increases the voltage, or strength, of the signals. (Sebuah peranti yang Menjana kembali isyarat analog disebut penguat. isyarat Analog melalui sebuah penguat, sebuah peranti elektronik yang meningkatkan voltan, atau kekuatan isyarat)

A device that regenerates a digital signal is called a repeater. (Sebuah peranti yang Menjana kembali isyarat digital disebut repeater(pengulang))

Attenuationbersambung pada 3/9/2012…….

Attenuation

An analog signal distorted by noise and then amplified

Attenuation…Cont…

A digital signal distorted by noise and then repeated

delay between the transmission of a signal and its eventual receipt. (penangguhan di antara penghantaran dan penerimaan akhir sesuatu isyarat)

Although electrons travel rapidly, they still have to travel, and a brief delay takes place between the moment you press the key and the moment the server accepts the data. This delay is called latency.

Latency