EC301 Chapter 3 (3.2)

3.2 Transmission Media In Networks

Twisted-pair cable consists of color-coded pairs of insulated copper wires. (Kabel Twisted-pair terdiri dari pasangan kod-warna yang membaluti wayar tembaga)

Every two wires are twisted around each other to form pairs and all the pairs are encased in a plastic sheath. (Setiap dua wayar berpintal diantara satu sama lain untuk membentuk membentuksatu pasangan dan semua pasangan wayar akan dibaluti di dalam sarung plastik)

The more twists per inch in a pair of wires, the more resistant the pair will be to crosstalk.

Twisted Pair Cable

It is relatively inexpensive, flexible, and easy to install. (ia murah, fleksibel, dan mudah untuk dipasang)

Twisted-pair cable falls into one of two categories: STP (shielded twisted-pair) or UTP (unshielded twisted-pair)

Twisted Pair Cable

surrounded by a shielding made of a metallic substance such as foil. (dikelilingi/dilindungi oleh perisai yang diperbuat dari bahan logam seperti aluminium foil)

The shielding acts as a barrier to external electromagnetic forces, thus preventing them from affecting the signals traveling over the wire inside the shielding

Twisted Pair Cable… STP (Shielded Twisted-Pair)

UTP does not contain additional shielding for the twisted pairs. (UTP tidak mengandungi pelindung tambahan untuk pasangan twisted)

Only consists of one or more insulated wire pairs encased in a plastic sheath. (Hanya terdiri dari satu atau lebih pasang wayar dan dibaluti di dalam sarung plastik)

Twisted Pair Cable… UTP (Unshielded Twisted-Pair)

Throughput—STP and UTP can both transmit data at 10, 100, and 1000 Mbps (1Gbps), depending on the grade of cabling and the transmission method in use. (kedua-dua STP dan UTP boleh menghantar data sebanyak 10, 100, dan 1000 Mbps (1Gbps), bergantung pada grad kabel dan kaedah penghantaran yang digunakan)

Cost—STP is more expensive than UTP because it contains more materials and it has a lower demand. (STP lebih mahal daripada UTP kerana ia mengandungi lebih banyak bahan/sumber)

Connector—STP and UTP use RJ-45 (Registered Jack 45) and RJ-11 (Registered Jack 11). (STP dan UTP menggunakan penyambung RJ-45 (Jack Terdaftar 45) dan RJ-11 (Registered Jack 11))


Noise immunity—Because of its shielding, STP is more noise-resistant than UTP. (disebabkan ia mengandungi pelindung, STP lebih tahan hingar(noise) daripada UTP)

Size and scalability—The maximum segment length for both STP and UTP is 100 m, or 328 feet. (Panjang maksimum segmen bagi kedua-dua STP dan UTP adalah 100 m, atau 328 kaki)


CAT 5e (Enhanced Category 5)—A higher-grade version of CAT 5 wiring that contains high-quality copper, offers a high twist ratio, and uses advanced methods for reducing crosstalk. Enhanced CAT 5 can support a signaling rate as high as 350 MHz, more than triple the capability of regular CAT 5.

CAT 6 (Category 6)—A twisted-pair cable that contains four wire pairs, each wrapped in foil insulation. Additional foil insulation covers the bundle of wire pairs, and a fire-resistant plastic sheath covers the second foil layer. The foil insulation provides excellent resistance to crosstalk and enables CAT 6 to support a 250-MHz signaling rate and at least six times the throughput supported by regular CAT 5.


CAT 6e (Enhanced Category 6)—A higher-grade version of CAT 6 wiring that reduces attenuation and crosstalk, and allows for potentially exceeding traditional network segment length limits. CAT 6e is capable of a 550 MHz signaling rate and can reliably transmit data at multi-Gigabit per second rates.

CAT 7 (Category 7)—A twisted-pair cable that contains multiple wire pairs, each surrounded by its own shielding, then packaged in additional shielding beneath the sheath. CAT 7 cabling is that it can support signal rates up to 1 GHz.


Coaxial cable consists of a central copper core surrounded by an insulator, a braided metal shielding, called braiding, and an outer cover, called the sheath or jacket. (Kabel Coaxial terdiri daripada teras tembaga pusat dikelilingi oleh pembalut, logam perisai, disebut braiding, dan penutup luar yang disebut sarung atau jaket)

The core carries the electromagnetic signal, and the braided metal shielding acts as both a shield against noise. (teras membawa isyarat elektromagnet, dan logam perisai bertindak sebagai perisai terhadap hingar)

all types have been assigned an RG (radio guide) specification number.

Coaxial cable

Coaxial cable

Coaxial cable F-Type connector

Have two categories: Thicknet and Thinnet.

Thicknet – Its diameter is approximately 1 cm– IEEE has designated Thinnet as 10BASE-5 Ethernet– maximum segment length are 500 meters.

Thinnet – Its diameter is approximately 0.64 cm– IEEE has designated Thinnet as 10BASE-2 Ethernet– maximum segment length are 185 meters (or roughly 200)

Coaxial cable…

Fiber-optic cable, or simply fiber, contains one or several glass or plastic fibers at its center, or core. (Kabel Fiber-optik mengandungi satu atau beberapa serat kaca atau plastik di pusatnya, atau teras)

Surrounding the fibers is a layer of glass or plastic called cladding. (sekeliling serat adalah lapisan kaca atau plastik yang disebut Cladding)

Outside the cladding, a plastic buffer protects the cladding and core. (Di bahagian luar cladding, buffer akan melindungi Cladding dan teras)

Fiber-optic Cable

To prevent the cable from stretching, and to protect the inner core further, strands of Kevlar (an advanced polymeric fiber) surround the plastic buffer. (Untuk mengelakkan kabel dari berlaku peregangan, dan untuk lebih melindungi bahagian teras, helai kevlar (suatu fiber/serat polimer) akan mengelilingi buffer)

Finally, a plastic sheath covers/outer jacket the strands of Kevlar. (Akhirnya, sarung/jaket plastik akan melindungi bahagian luar kevlar)

Have two categories: single-mode and multimode.

Fiber-optic Cable

Fiber-optic Cable

SMF (single-mode fiber) uses a narrow core (less than 10 microns in diameter) through which light generated by a laser travels over one path, reflecting very little. (menggunakan teras yang kecil(kurang dari 10 mikron dalam diameter) yang mana cahaya yang dihasilkan oleh laser dihantar melalui satu jalur, pantulan sangat sedikit)

Because it reflects little, the light does not disperse as the signal travels along the fiber. (Oleh kerana pantulannya sedikit, cahaya tidak akan tersebar sebagai isyarat perjalanan sepanjang melalui serat)

accommodate high bandwidths and long distances. (menyediakan bandwidth yang tinggi dan jarak yang panjang)

Fiber-optic Cable…SMF (Single-Mode Fiber)

MMF (multimode fiber) contains a core with a larger diameter than single-mode fiber (between 50 and 115 microns in diameter; the most common size is 62.5 microns) over which many pulses of light generated by a laser or LED travel at different angles. (mengandungi teras dengan diameter yang lebih besar daripada serat single-mode (antara 50 dan 115 mikron diameter; saiz paling umum adalah 62,5 mikron) di mana banyak pulsa cahaya yang dihasilkan oleh laser atau LED bergerak pada sudut yang berbeza)

It is commonly found on cables that connect a router to a switch or a server on the backbone of a network. (kebiasaanya dijumpai pada kabel yang menghubungkan router ke switch atau server di tulang belakang rangkaian)

Fiber-optic Cable…MMF (Multimode Fiber)

Fiber-optic Cable

Fiber-optic Cable…Connector

(a) ST (Straight Tip) (b) SC (Standard Connector)

(c) LC (Local Connector) (d) MT-RJ (Mechanical Transfer Registered Jack)

Throughput—Fiber has proved reliable in transmitting data at rates that exceed 10 Gigabits (or 10,000 Megabits) per second. (Fiber telah terbukti cekap dalam penghantaran data pada tahap yang melebihi 10 Gigabits (atau 10,000 Megabits) per saat)

Cost—Fiber-optic cable is the most expensive transmission medium. (Kabel Fiber-optik adalah media penghantaran paling mahal)

Noise immunity—Because fiber does not conduct electrical current to transmit signals,it is unaffected by EMI. (disebabkan serat tidak mengalirkan arus elektrik untuk menghantar isyarat, ia tidak akan dipengaruhi oleh EMI)

Fiber-optic Cable…characteristics

Size and scalability—Depending on the type of fiber-optic cable used, segment lengths from 150 to 40,000 meters. (Bergantung pada jenis kabel serat optik yang digunakan, panjang segmen antara 150 hingga 40,000 meter)

Fiber-optic Cable…characteristics

Networks that transmit signals through the atmosphere via infrared or radiofrequency (RF) waves are known as wireless networks. (Rangkaian yang menghantar isyarat melalui atmosfera menerusi inframerah atau gelombang frekuensi radio yang dikenali sebagai rangkaian wayarles)

All wireless signals are carried through the air along electromagnetic waves. (Semua isyarat wayarles dibawa melalui udara di sepanjang gelombang elektromagnet)

Wireless spectrum is a continuum of electromagnetic waves used for data and voice communication. (spektrum wayarles merupakan jalur gelombang elektromagnet yang digunakan untuk komunikasi data dan suara)

Wireless Transmission

Wireless Transmission

Signal propagation Signal degradation Narrowband, broadband and spread spectrum signal Fixed and mobile wireless communication

Characteristic of Wireless Transmission

The signal may pass through the object or be absorbed by the object, or it may be subject to any of the following phenomena: reflection, diffraction, or scattering. (isyarat boleh melewati objek atau diserap oleh objek, atau mungkin mengalami salah satu fenomena berikut: pantulan, pembelauan, atau penghamburan)

Reflection The wave encounters an obstacle and reflects—or bounces back—toward its source. A wireless signal will bounce off objects whose dimensions are large compared to the signal’s average wavelength. (gelombang bertembung dengan halangan dan memantul kembali menuju sumbernya. Isyarat wayarles bertembung dengan objek yang lebih besar berbanding dengan panjang gelombang isyarat itu)

Signal propagation

In diffraction, a wireless signal splits into secondary waves when it encounters an obstruction. The secondary waves continue to propagate in the direction in which they were split. (isyarat wayarles terbahagi menjadi gelombang sekunder ketika bertembung dengan suatu penghalang. Gelombang sekunder akan terus merambat pada arah di mana mereka berpecah)

Scattering is the reflection in multiple different directions, of a signal. Scattering occurs when a wireless signal encounters an object that has small dimensions compared to the signal’s wavelength. (adalah pantulan dalam beberapa arah signal yang berbeza. Scattering terjadi apabila isyarat wayarles bertembung dengan objek yang berukuran lebih kecil berbanding dengan panjang gelombang isyarat itu)

Signal propagation

Signal propagation

the original signal issued by the transmitter will experience fading, or a change in signal strength as a result of some of the electromagnetic energy being scattered, reflected, or diffracted after being issued by the transmitter. (isyarat asal yang dikeluarkan oleh penghantar akan mengalami pengurangan atau perubahan dalam kekuatan isyarat disebabkan oleh penghamburan, pantulan, atau pembelauan selepas dikeluarkan oleh penghantar)

the strength of the signal that reaches the receiver is lower than the transmitted signal’s strength. (kekuatan isyarat yang dicapai penerima lebih rendah dari kekuatan isyarat penghantar)

the farther it moves away from the transmission antenna the more it weakens. (semakin jauh bergerak dari antena penghantaran ia akan semakin melemah)

Signal degradation

Interference can distort and weaken a wireless signal in the same way that noise distorts and weakens a wire-bound signal. (gangguan dapat mengubah bentuk dan melemahkan isyarat wayarles dengan cara yang sama sebagaimana yang berlaku pada kabel)

Because wireless signals cannot depend shielding to protect them from extraneous EMI, they are more vulnerable to noise. (Kerana isyarat wayarles tidak dapat bergantung pada perisai untuk melindungi mereka dari EMI asing, mereka lebih terdedah kepada hingar)

Signal degradation

In narrowband, a transmitter concentrates the signal energy at a single frequency or in a very small range of frequencies. (Dalam Narrowband, pemancar menumpukan tenaga isyarat pada frekuensi tunggal atau dalam julat frekuensi yang tersangat kecil)

broadband uses a relatively wide band of the wireless spectrum. As a result of their wider frequency bands, offer higher throughputs than narrowband technologies. (broadband menggunakan sebuah jalur relatif yang lebar dari spektrum wayarles. disebabkan dari jalur frekuensi yang lebih luas, maka throughputs lebih tinggi berbanding dengan teknologi Narrowband.)

Narrowband, broadband and spread spectrum signal

The use of multiple frequencies to transmit a signal is known as spread spectrum technology. (Penggunaan beberapa frekuensi untuk menghantar isyarat dikenali sebagai teknologi spread spectrum)

spread spectrum signaling is called FHSS (frequency hopping spread spectrum) & DSSS (direct sequence spread spectrum). (spread spectrum isyarat adalah FHSS (hopping spread spectrum) & DSSS (direct sequence spread spectrum))


FHSS a signal jumps between several different frequencies within a band in a synchronization pattern known only to the channel’s receiver and transmitter. (isyarat melompat antara beberapa frekuensi yang berbeza dalam sebuah jalur dalam pola penyegerakan yang hanya diketahui oleh penerima saluran dan pemancar)



DSSS a signal’s bits are distributed over an entire frequency band at once. Each bit is coded so that the receiver can reassemble the original signal upon receiving the bits. (bit isyarat yang diedarkan melalui keseluruhan jalur frekuensi sekaligus. Setiap bit dikodekan sehingga penerima boleh mengumpul semula isyarat asal ketika menerima bit)

Each type of wireless communication falls into one of two categories: fixed or mobile. (terdapat 2 kategori: fiexed atau mobile)

Fixed wireless– the locations of the transmitter and receiver do not move. (lokasi

penghantar dan penerima tidak berubah)

– The transmitting antenna focuses its energy directly toward the receiving antenna. (Penghantaran antena ini memfokuskan tenaga terus ke antena penerima)

– advantage of fixed wireless is that because the receiver’s location is predictable, energy need not be wasted issuing signals across a large geographical area. (kelebihannya, oleh kerana lokasi penerima adalah telah diketahui, tenaga tidak perlu disia-siakan membawa isyarat menerusi kawasan geografi yang besar)

Fixed and mobile wireless communication

mobile wireless– the receiver can be located anywhere within the

transmitter’s range. (penerima boleh berada di mana sahaja dalam liputan pemancar itu)

– Allows the receiver to roam from one place to another while continuing to pick up its signal. (Membolehkan penerima untuk bergerak dari satu tempat ke tempat lain, sambil terus memperolehi signalnya)

Fixed and mobile wireless communication

two types of wireless connections used on computer networks: infrared and wireless LANs. (dua jenis Sambungan wayarles digunakan pada rangkaian komputer: LAN inframerah dan wayarles)

Infrared– transmitted by frequencies in the 300-GHz to 300,000-GHz

range, which is just above the top of the wireless spectrum. (dihantar dengan julat frekuensi GHz 300 hingga 300.000-GHz, iaitu spektrum wayarles tertinggi )

– infrared transmission is most often used for communications between devices in the same room. (penghantaran inframerah ini paling sering digunakan untuk komunikasi antara peranti dalam ruangan yang sama)

types of wireless connections…infrared

– infrared signaling requires more power, travels shorter distances, and transmission around obstacles less successfully than the wireless technique. (isyarat inframerah lebih memerlukan kekuatan, jarak pendek, dan penghantaran di sekitar rintangan kurang berjaya berbanding teknik wayarles)

wireless LANs– WLAN relies on lower frequencies in the 2.4-2.4835 GHz

band, more commonly known as the 2.4-GHz band, to send and receive signals. (WLAN menghantar dan menerima isyarat pada frekuensi rendah iaitu 2.4 GHz)

– two categories: ad hoc and infrastructure

types of wireless connections…wireless LANs

Smaller wireless networks, in which a small number of nodes closely positioned need to exchange data, can be arranged in an ad hoc. (Rangkaian wayarles yang lebih kecil, di mana sejumlah nod berdekatan yang ingin bertukar data, diatur dalam ad hoc)

In an ad hoc WLAN, wireless nodes, or stations, transmit directly to each other via wireless NICs without an intervening connectivity device. (Dalam WLAN ad hoc, nod atau stesen, menghantar terus antara satu sama lain melalui NIC wayarles(wireless adapter) tanpa memerlukan peranti sambungan)

wireless LANs… ad hoc

infrared and wireless LANs connection

An ad-hoc WLAN

WLANs can use the infrastructure mode, which depends on an intervening connectivity device called an access point. (WLAN yang menggunakan mode infrastruktur akan bergantung kepada peranti sambungan tambahan yang disebut access point)

AP (access point) is a device that accepts wireless signals from multiple nodes and retransmits them to the rest of the network. (AP adalah peranti yang menerima isyarat wayarles dari beberapa node dan menghantarnya kembali ke seluruh rangkaian)

wireless LANs… infrastructure

an access point must have sufficient power and be strategically placed so that stations can communicate with it. ( access point mesti mempunyai kekuatan yang cukup dan diletakkan secara strategik sehingga dapat berkomunikasi dengan stesen-stesen)

like other wireless devices, access points contain an antenna connected to their transceivers. (seperti peranti wayarles lain, access point mengandungi antena bersambung kepada transceivers)

wireless LANs… infrastructure


An infrastructure WLAN


Wireless LAN interconnection

Bersambung pada 6/9/2012………..

Documents

EC301 Chapter 3 (3.2)