Transmission Media

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JARINGAN TELEKOMUNIKASI

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Tipe-tipe Media Transmisi

Guided transmission media

Kabel tembaga

Open Wires

Coaxial

Twisted Pair

Kabel serat optik

Unguided transmission media

infra merah

gelombang radio

microwave: terrestrial maupun satellite

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Waves are guided along solid medium

Guided Transmission Media 4

Model Saluran Transmisi

Menurut Telegrapher's Equations, suatu saluran transmisi terdiri dari serangkaian komponen kutub dua yang jumlahnya tak terhingga

R menyatakan resistensi konduktor

L menyatakan induktansi salurann

C menyatakan kapasitansi antara dua konduktor

G menyatakan konduktansi materi dielektrik yang memisahkan kedua konduktor

Impedansi karakteristik dinyatakan oleh

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Kabel Tembaga 6

Paling lama dan sudah biasa digunakan

Kelemahan: redaman tinggi dan sensitif terhadap interferensi

Redaman pada suatu kabel tembaga akan meningkat bila frekuensi dinaikkan

Kecepatan rambat sinyal di dalam kabel tembaga mendekati 200.000 km/detik

Tiga jenis kabel tembaga yang biasa digunakan: Open wire Coaxial Twisted Pair

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Open wire 7

Sudah jarang digunakan

Kelemahan:

Terpengaruh kondisi cuaca dan lingkungan

Kapasitas terbatas (hanya sekitar 12 kanal voice)

70 miles open wire from Hawthorne to Tonopah

Photograph taken by Brian Hayes in 1999

(http://flickr.com/photos/brianhayes/321552411/)

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Coaxial

(A)

(B)

(C)

(D)

Bandwidth lebar (45-500 MHz) Lebih kebal terhadap interferensi

Contoh penggunaan : pada antena TV, LAN dsb.

RG58 coax and BNC Connector

Twisted pair

Twisted pair dibangun dari dua konduktor yang dipilin Kabel dipilin untuk mengeliminasi crosstalk

Pada suatu bundel twisted pair (lebih dari satu pasang), twist length (twist rates) masing-masing pasangan dibedakan untuk mencegah crosstalk antar pasangan

Pengiriman sinyal pada twisted pair menggunakan balance signaling untuk mengeliminasi pengaruh interferensi (noise)

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Balance Signaling

A balanced transmission line is one whose currents

are symmetric with respect to ground so that all current flows through the transmission line and the

load

none through ground

Note that line balance depends on the current through the line, not the voltage across the line

It is also called differential signaling

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Source: York County Amateur Radio Society

Examples of a Balanced Line All using DC rather than AC to simplify the analysis

Notice that the currents are equal and opposite and that the total current flowing through ground = 25mA-25mA = 0

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I = 25 mA

V = +6 VDC

6 V

6 V

V = -6 VDC

I = -25 mA

240

240

Example #1

Note that the total current flowing through ground is again 0

Because the ground current is 0, the ground is not required

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I = 25 mA

V = +9 VDC

V = -6 VDC

I = -25 mA

360

240

Example #2

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Is the line balanced?

No although the voltages are equal and opposite, the currents are not!

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Example #3

V = +6 VDC

V = -6 VDC

300

240

I = 20 mA

I = -25 mA

FYI:

Coaxial is an example of unbalanced transmission line

Many types of antenna (dipoles, yagi etc.) are balanced load

So, to feed balanced antenna with unbalance transmission lines we have to use baluns (balance-unbalance)

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Twisted pairs Types

Unshielded Twisted pair (UTP)

Shielded Twisted pair (STP)

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Unshielded Twisted pair (UTP)

Category 1- originally designed for voice telephony only, but thanks to some new techniques, long-range Ethernet and DSL, operating at 10Mbps and even faster, can

be deployed over Cat 1

Category 2 - accommodate up to 4Mbps and is associated with token-ring LANs.

Category 3 - Cat 3 cable operates over a bandwidth of 16MHz on UTP and supports up to 10Mbps over a range of 330 feet (100 m).

Key LAN applications include 10Mbps Ethernet and 4Mbps token-ring LANs.

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UTP (cont.)

Category 4 operates over a bandwidth of 20MHz on UTP

can carry up to 16Mbps over a range of 330 feet (100 m).

The key LAN application is 16Mbps token ring.

Category 5 operates over a bandwidth of 100MHz on UTP

Can handle up to 100Mbps over a range of 330 feet (100m).

Cat 5 cable is typically used for Ethernet networks running at 10Mbps

or 100Mbps.

Key LAN applications include 100BASE-TX, ATM, CDDI, and 1000BASE-T.

It is no longer supported, having been replaced by Cat 5e.

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Category 5e Cat 5e (enhanced) operates over a bandwidth of 100MHz on UTP, with a range

of 330 feet (100 m).

The key LAN application is 1000BASE-T.

The Cat 5e standard is largely the same as Category 5, except that it is

made to somewhat more stringent standards.

Category 5e is recommended for all new installations and was designed

for transmission speeds of up to 1Gbps (Gigabit Ethernet).

Although Cat 5e can support Gigabit Ethernet, it is not currently certified

to do so.

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UTP (cont.)

Category 6 - specified under ANSI/TIA/EIA-568-B.2-1,

Operates over a bandwidth of up to 400MHz

Supports up to 1Gbps over a range of 330 feet (100 m).

Cable standard for Gigabit Ethernet and other network protocols that is backward compatible with the Cat 5/5e and Cat 3 cable standards.

Cat 6 features more stringent specifications for crosstalk and system noise.

Cat 6 is suitable for 10BASE-T/100BASE-TX and 1000BASE-T (Gigabit Ethernet) connections.

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Shielded Twisted Pair (STP)

Twisted pair cables are often shielded in attempt to prevent electromagnetic interference.

Because the shielding is made of metal, it may also serve as a ground.

However, usually a shielded or a screened twisted pair cable has a special grounding wire added called a drain wire.

This shielding can be applied to individual pairs, or to the collection of pairs.

When shielding is applied to the collection of pairs, this is referred to as screening.

The shielding must be grounded for the shielding to work.

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STP (cont.)

Screened unshielded twisted pair (S/UTP)

Also known as Fully shielded (or Foiled) Twisted Pair (FTP), is a screened UTP cable (ScTP).

Shielded twisted pair (STP or STP-A)

Screened shielded twisted pair (S/STP or S/FTP)

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Screened unshielded twisted pair (S/UTP)

ET2080 Jaringan Telekomunikasi

Shielded twisted pair (STP or STP-A)

1 Jacket

2 Shield-foil

3 Drain wire 4 Solid twisted pair

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Screened shielded twisted pair (S/STP or S/FTP)

1 Jacket

2 Rip-cord

3 Shield-foil

4 Drain wire

5 Protective skin

6 Polymer tape

7 Solid twisted pair

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Category 7

Cat 7 is specified in the frequency range of 1MHz to 600MHz. ISO/IEC11801:2002 Category 7/Class F is a cable standard for Ultra

Fast Ethernet and other interconnect technologies that can be made

backward compatible with traditional Cat 5 and Cat 6 Ethernet cable.

Cat 7, which is based on four twisted copper pairs, features even more

stringent specifications for crosstalk and system noise than Cat 6.

To achieve this, shielding has been added for individual wire pairs and the cable as a whole

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Cable Legend 26

Optical Fiber 27

Optical Fiber Advantages

Weight and Size Fiber cable is significantly smaller and lighter than electrical cables to do the same job

Material Cost Fiber cable costs significantly less than copper cable for the same transmission capacity

Information Capacity Recently, bit-rates of up to 14 Tbit/s have been reached over a single 160 km line using optical amplifiers

No Electrical Connection Electrical connections have problems:

Ground loops (in a conductor connecting two points that are supposed to be at the same potential, often ground, but are

actually at different potentials) causing noises and interferences

Dangerous (must be protected)

Lightning poses a severe hazard

No Electromagnetic Interference Because the connection is not electrical, you can neither pick up nor create electrical interference (the

major source of noise)

Longer distances between Regenerators (hundreds of kilometers) Open Ended Capacity

The maximum theoretical capacity of installed fiber is very great (almost infinite)

Better Security It is possible to tap fiber optical cable. But it is very difficult to do and the additional loss caused by the tap is relatively

easy to detect

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Optical Fiber Elements

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Core

Carries the light signal (pure silica glass and doped with germanium)

Cladding

Keeps light signal within core (Pure Silica Glass)

Coating

Protects Optical Fiber From Abrasion and External Pressures (UV Cured Acrylate)

Mengapa cahaya bisa bergerak sepanjang serat optik?

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Karena ada fenomena Total Internal Reflection (TIR)

TIR dimungkinkan dengan membedakan indeks bias (n) antara core dan clading

Dalam hal ini ncore > ncladding

Memanfaatkan hukum Snellius

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Remembering Snellius 31

ncore > ncladding

Critical angle

At the critical angle we know that equals 90 and sin 90 = 1 and so

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for rays where 1 is less than a critical value then the ray will propagate along the fiber and will be bound within the fiber

(Total Internal Reflection)

where the angle 1 is greater than the critical value the ray is refracted into the cladding and will ultimately be lost outside the

fiber

Numerical Aperture (NA) 34

Light Modes

Can be as few as one mode and as many as tens of

thousands of modes

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Fiber Transmission Windows (Bands) 36

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Transmitter Light Sources

Light Emitting Diodes (LED) Used for multimode: 850 nm or 1300 nm Wide beam width fills multimode fibers Wider spectrum (typically 50 nm) Inexpensive Cannot modulate as fast as lasers

VCSELsVertical Cavity Surface Emitting Laser Used for multimode at 850 and 1300 nm Quite narrow spectrum Narrow beam width (does not fill multimode fibers) Much less expensive than FP or DFB lasers

Fabry-Perot (FP) and Distributed Feedback (DFB) Lasers Used for singlemode: 1310 nm or 1550 nm Narrow spectrum (can be less than 1 nm) Narrow beam width (does not fill multimode fibers) Highest power and fastest switchingMost expensive

(especially DFB)

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Salah satu cara untuk mengidenifikasi konstruksi kabel optik adalah dengan menggunakan perbandingan antara diameter core dan cladding. Sebagai contoh adalah tipe kabel 62.5/125. Artinya diamater core 62,5 micron dan diameter cladding 125 micron

Contoh lain tipe kabel:50/125, 62.5/125 dan 8.3/125

Jumlah core di dalam satu kabel bisa antara 4 s.d. 144

Klasifikasi Serat Optik 39

Berdasarkan mode gelombang cahaya yang berpropagasi pada serat optik

Multimode Fibre

Singlemode Fibre

Berdasarkan perubahan indeks bias bahan

Step index fibre

Gradded index fibre

Step Index Fiber vs Gradded Index Fiber 40

Pada step index fiber, perbedaan antara index bias inti dengan index bias cladding terjadi secara drastis

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Pada gradded index fiber, perbedaan index bias bahan dari inti sampai

cladding berlangsung secara gradual

Contoh profile gradded index:

Untuk 0 r a

r = jari-jari di dalam inti serat

a = jari-jari maksimum inti serat

Multimode Optical Fiber 42

Step-index multimode. Used with 850nm, 1300 nm source.

Graded-index multimode. Used with 850nm, 1300 nm source.

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Singlemode Optical Fiber 43

Bandwidth-distance product

Because the effect of dispersion increases with the length of the fiber, a fiber Information carrying capacity is often characterized by its bandwidth-distance product, often expressed in units of MHzkm.

This value is a product of bandwidth and distance because there is a trade off between the bandwidth of the signal and the distance it can be carried

For example, a common multimode fiber with bandwidth-distance product of 500 MHzkm could carry a 500 MHz signal for 1 km or a 1000 MHz signal for 0.5 km.

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Fiber Optic Installation Safety Rules

Keep all food and beverages out of the work area. If fiber particles are ingested they can cause internal hemorrhaging

Wear disposable aprons to minimize fiber particles on your clothing Fiber particles on your clothing can later get into food, drinks, and/or be ingested by other means

Always wear safety glasses with side shields and protective gloves Treat fiber optic splinters the same as you would glass splinters.

Never look directly into the end of fiber cables until you are positive that there is no light source at the other end Use a fiber optic power meter to make certain the fiber is dark. When using an optical tracer or continuity

checker, look at the fiber from an angle at least 6 inches away from your eye to determine if the visible light is present..

Only work in well ventilated areas

Contact wearers must not handle their lenses until they have thoroughly washed their hands. Do not touch your eyes while working with fiber optic systems until they have been thoroughly washed

Keep all combustible materials safely away from the curing ovens Put all cut fiber pieces in a safe place. Thoroughly clean your work area when you are done

Do not smoke while working with fiber optic systems. Source: http://www.jimhayes.com/

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Provides a means for transmitting electro-magnetic signals through the air but do not guide them (wireless transmission)

Unguided Transmission Media 46

Electromagnetic Spectrum for Wireless Communication

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3 kHz 300 GHz 400 THz 900 THz

Radio wave and microwave Infra Red Light wave

Transmission and reception are achieved by means

of antennas

For transmission, an antenna radiates electromagnetic radiation in the air

For reception, the antenna picks up electromagnetic waves from the surrounding medium

The antenna plays a key role

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Directional Antenna

the transmitting

antenna puts out a focused

electromagnetic beam

the transmitting and

receiving antennas must be aligned

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Dr. Yagi and his Yagi antenna

(example of directional antenna)

Omnidirectional Antenna

the transmitted signal

spreads out in all directions and can be

received by many antennas

In general, the higher

the frequency of a signal, the more it is

possible to focus it into a directional beam

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Microwave

Frequencies in the range of about 30 MHz to 40

GHz are referred to as microwave frequencies

2 GHz to 40 GHz

wavelength in air is 0.75cm to 15cm

wavelength = velocity / frequency

highly directional beams are possible

suitable for point-to-point transmission

30 MHz to 1 GHz

suitable for omnidirectional applications

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Terrestrial Microwave 52

Terrestrial Microwave

Limited to line-of-sight (LOS) transmission

This means that microwaves must

be transmitted in a straight line and that no obstructions can

exists, such as buildings or

mountains, between microwave stations.

To avoid possible obstructions, microwave antennas often are positioned on the tops of buildings, towers, or mountains

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Applications

Long-distance telecommunication service

requires fewer amplifiers or repeaters than coaxial cable

requires line-of-sight transmission

Example

telephone system

TV distribution

Short point-to-point links

Data link between local area network

closed-circuit TV

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Another apps: cellular communication, and LANs

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Freq. Band Use Range Data Rate

824 - 894 MHz Analog cell phones (AMPS) 20 km per cell 13 kbps/channel

902-928 MHz License free in North America

1.7 - 2.3 GHz PCS digital cell phones < 1 km per cell

1.8 GHz GSM digital cell phones 16 kbps/channel

2.400-2.484 GHz global license free band

2.4 GHz 802.11, Lucent WaveLAN 100 m - 25 km 2 - 11 Mbps

2.45 GHz Bluetooth about 10 m 1 Mbps

4 - 6 GHz commercial (telecomm.) 40 - 80 km 100 Mbps

Infrared short distance line of sight 5 - 100 m 1 Mbps

Freq. Band Use Range Data Rate

824 - 894 MHz Analog cell phones (AMPS) 20 km per cell 13 kbps/channel

902-928 MHz License free in North America

1.7 - 2.3 GHz PCS digital cell phones < 1 km per cell

1.8 GHz GSM digital cell phones 16 kbps/channel

2.400-2.484 GHz global license free band

2.4 GHz 802.11, Lucent WaveLAN 100 m - 25 km 2 - 11 Mbps

2.45 GHz Bluetooth about 10 m 1 Mbps

4 - 6 GHz commercial (telecomm.) 40 - 80 km 100 Mbps

Infrared short distance line of sight 5 - 100 m 1 Mbps

Transmission characteristics

The higher the frequency used, the higher the

potential bandwidth and therefore the higher the potential data rate

Band (GHz) | Bandwidth (MHz) | Data rate (Mbps)

2 7 12

6 30 90

11 40 90

18 220 274

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Attenuation

d is the distance

is the wavelength

repeaters or amplifiers may be placed farther apart for microwave systems - 10 to 100 km is typical

Attenuation increases with rainfall, especially above 10 GHz The assignment of frequency bands is strictly regulated

(http://www.postel.go.id/utama.aspx?MenuID=3&MenuItem=3)

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log10

=

dL Satellite Microwave 58

a satellite is a microwave relay

station link two or more ground-based

microwave transmitter/receivers

(known as earth stations or ground stations)

The satellite receives transmissions on one frequency

band (uplink), amplifies or

repeats the signal, and transmits it on another frequency

(downlink) An orbiting satellite operate on a

number of frequency bands,

called transponder channels

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Geostationary Satellites

It is launched into an orbit above the equator at 35786 km This orbit distance means that the satellite

is orbiting the earth as fast as the earth

is rotating.

It appears to earth stations that the satellite is stationary, thus making communications more reliable and

predictable

Earth stations is less expensive because

they can use fixed antennas

Delay is 250 -500ms for geostationary satellites

Apps: television broadcasting and weather forecasting, and have a number

of important defense and intelligence applications, VSAT

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VSAT

A Very Small Aperture Terminal (VSAT), is a two-way satellite ground station with

a dish antenna that is smaller than 3 meters.

Most VSAT antennas range from 75 cm to 1.2 m.

Data rates typically range from 56 Kbit/s up to 4 Mbit/s

VSATs access satellites in geosynchronous (geostationary) orbit (to relay data from

small remote earth stations (terminals) to other terminals (in mesh configurations)

or master earth station "hubs" (in star configurations).

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Low earth orbit (LEO) and Medium earth orbit (MEO) satellites

For small mobile personal communications terminals,

a network with significantly reduced transmission and processing delay is required

Such a service could be provided by low earth orbit (LEO) and medium earth orbit (MEO) satellite systems

These systems can provide direct personal-terminal-to-personal-terminal connectivity (satellite phone

services)

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LEO

A Low Earth Orbit (LEO) typically is a circular orbit about 400 kilometers above the earths surface and, correspondingly, a period (time to revolve around the earth) of about 90 minutes

One of apps: to provide satellite phone services, primarily to remote areas

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MEO

Medium Earth orbit (MEO), sometimes called intermediate circular orbit (ICO), is the region of space around the Earth above low Earth orbit (altitude of 2,000 kilometers (1,243 mi)) and below geostationary orbit (altitude of 35,786 kilometers (22,236 mi))

The most common use for satellites in this region is for navigation, such as the GPS

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Frequency allocation

Optimum frequency range for satellite transmission

is 1 - 10GHz

Below 1 GHz, there is significant noise from nature

sources

About 10 GHz, the signal is severely attenuated by atmosphere

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Fixed satellite service

Typical frequency bands for

uplink/downlink usual terminology

6/4 GHz C band

8/7 GHz X band

14/12 GHz Ku band

30/20 GHz Ka band

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Mobile satellite service



1.6/1.5 GHz L band

30/20 GHz Ka band

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Broadcasting satellite service



12 GHz Ku band

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Broadcast Radio 69 Physical description

omnidirectional

Applications

AM broadcasting

Operating frequencies

MF (medium frequency): 300 kHz - 3 MHz

HF (high frequency): 3 MHz - 30 MHz

HF is the most economic means of low information rate

transmission over long distances (e.g. > 300km)

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A HF wave emitted from an antenna is characterized by a groundwave and a skywave components.

The groundwave follows the surface of the earth and can provide useful communication over salt water up to 1000km and over land for some 40km to 160km

The skywave transmission depends on ionospheric refraction. Transmitted radio waves hitting the ionosphere are bent or

refracted. When they are bent sufficiently, the waves are returned to

earth at a distant location. Skywave links can be from 160km to 12800km.

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FM broadcasting

operating frequencies

VHF (very high frequency): 30 MHz - 300 MHz

TV broadcasting

operating frequencies:

VHF

UHF (ultra high frequency): 300 MHz - 3000MHz

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Infrared 74

Does not penetrate walls

no security or interference problems

no frequency allocation issue

no licensing is required

Apps: Infrared Wireless LAN

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So..youve heard about dB.. What is it?

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Decibel, Gain, dan Loss 77

Power loss : penurunan daya sinyal

Power gain : penguatan daya sinyal

Decibel : satuan untuk menyatakan power loss/gain

Decibel merupakan satuan ukuran daya yang logaritmis

Pertama kali digunakan oleh

Alexander Graham Bell (satuan decibel digunakan untuk

menghormati jasanya)

Decibel : dB

Alexander Graham Bell Born 1847 - Died 1922

Decibel in Action

Gain

g = Pout/Pin

Gain in dB

gdB = 10 log (Pout/Pin)

Loss

L = Pin/Pout

Loss in dB

LdB = 10 log (Pin/Pout)

Overall Gain

g = g1*g2

Overall Gain in dB

gdB = g1(dB) + g2(dB)

Contoh: - Bila daya output 10 Watt dan daya input 1 Watt, maka Gain = 10 dB - Bila daya input 10 Watt dan daya output 1 Watt,

maka Loss = 10 dB (atau Gain = -10 dB)

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Rumus dB menyatakan ukuran daya

Jika kita lebih tertarik akan perubahan pada tegangan maka faktor impedansi harus dimasukkan pada perhitungan dB

Z

Z log 10

V

V log 20

P

P log 10

out

in

in

out

in

out

+

=

=dBg

Power Levels in dB 80

Sampai titik ini kita masih melihat penerapan dB

untuk menyatakan perbandingan daya

Bagaimana cara menyatakan level daya absolut

menggunakan dB?

Gunakan suatu daya referensi

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Daya referensi yang banyak digunakan adalah 1 mW

Satuan dB yang dihasilkan adalah dBm

Contoh: suatu level daya 10 mW bila dinyatakan di dalam dB adalah 10 dBm

Daya referensi lain yang dapat digunakan: 1 Watt (satuan dB yang digunakan dBW)

=

=

W

PP

mW

PP

dBW

dBm

1 log 10

1 log 10

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Contoh penggunaan dB

Daya pancar P1 = 1W atau +30 dBm Gain antena = 30 dB

Redaman link = 110 dB Daya diterima terima P2,dBm = +30 dBm + 30 dB 110 dB +30 dB = 20 dBm

Bila dinyatakan di dalam Watt P2 = 10 W.

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Redaman serat optik 0,5 dB/km

Daya pancar P1,dBm = 0 dBm Redaman serat optik = 0,5 dB/km, maka redaman total serat optik = 0,5*40 =20 dB

Daya terima P2,dBm = 0 dBm 20 dB = 20 dBm

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Satuan lain yang biasa digunakan

untuk menyatakan suatu perbadingan adalah Neper

1 Neper (Np) = 8,685889638 dB

1 dB = 0,115129254 Np John Napier or Neper nicknamed Marvellous Merchiston

(1550, 1617) Penemu Logaritma

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