ET2080 JARINGAN TELEKOMUNIKASI

Report
ET2080 JARINGAN TELEKOMUNIKASI
STEI - ITB
Tutun Juhana – Program Studi Teknik Telekomunikasi
Tipe-tipe Media Transmisi
2

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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Guided Transmission Media
Waves are guided along solid medium
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Model Saluran Transmisi
5


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
• Bandwidth lebar (45-500 MHz)
• Lebih kebal terhadap interferensi
• Contoh penggunaan : pada antena TV,
LAN dsb.
= CORE (D)
= DIELECTRIC (C)
= SHIELD (B)
= JACKET (A)
RG58 coax and BNC Connector
8
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Source: Radio Laboratory Handbook, School On Digital Radio Communications for
Research and Training in Developing Countries, ICTP
9
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Twisted pair
10

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
11

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
Source: York County Amateur Radio Society
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Examples of a Balanced Line
All using DC rather than AC to simplify the analysis
12
V = +6 VDC
Example #1
I = 25 mA
6V


6V
I = -25 mA
V = -6 VDC

Notice that the currents are equal and opposite and that the
total current flowing through ground = 25mA-25mA = 0
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V = +9 VDC
I = 25 mA
Example #2


I = -25 mA
V = -6 VDC


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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V = +6 VDC
Example #3
I = 20 mA


I = -25 mA
V = -6 VDC


Is the line balanced?
No – although the voltages are equal and opposite,
the currents are not!
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
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 (balanceunbalance)
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Twisted pairs Types
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

Unshielded Twisted pair (UTP)
Shielded Twisted pair (STP)
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Unshielded Twisted pair (UTP)
17



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.)
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
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.)
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
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)
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




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.)
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
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)
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Shielded twisted pair (STP or STP-A)
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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)
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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
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
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
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Optical Fiber
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Optical Fiber Advantages
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
Weight and Size


Material Cost


Fiber cable costs significantly less than copper cable for the same transmission capacity
Information Capacity


Fiber cable is significantly smaller and lighter than electrical cables to do the same job
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:




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


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
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


Cladding


Carries the light signal (pure silica glass and
doped with germanium)
Keeps light signal within core (Pure Silica
Glass)
Coating

Protects Optical Fiber From Abrasion and
External Pressures (UV Cured Acrylate)
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Mengapa cahaya bisa bergerak sepanjang
serat optik?
31


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
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ncore > ncladding
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
Critical angle
the critical angle we know that q² equals 90° and sin
90° = 1 and so
 At
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

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for rays where q1 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 q1 is greater than the critical value the ray is
refracted into the cladding and will ultimately be lost outside the
fiber
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Numerical Aperture (NA)
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Light Modes
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
Can be as few as one mode and as many as tens of
thousands of modes
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Fiber Transmission Windows (Bands)
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Transmitter Light Sources
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
Light Emitting Diodes (LED)






VCSEL’s–Vertical Cavity Surface Emitting
Laser





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
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 switching–Most 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
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Klasifikasi Serat Optik
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
Berdasarkan mode gelombang cahaya yang
berpropagasi pada serat optik
Multimode Fibre
 Singlemode Fibre


Berdasarkan perubahan indeks bias bahan
Step index fibre
 Gradded index fibre

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Step Index Fiber vs Gradded Index Fiber
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
Pada step index fiber, perbedaan antara index bias
inti dengan index bias cladding terjadi secara drastis
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

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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
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Multimode Optical Fiber
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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
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Distortions in Fiber
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
If a short pulse of light from a source such as a laser
or an LED is sent down a narrow fiber, it will be
changed (degraded) by its passage down the fiber
It will emerge (depending on the distance) much weaker
 lengthened in time (“smeared out”), and
 distorted in other ways


The reasons for the above are as follows:
Attenuation
 Maximum Power
 Polarization
 Dispersion
 Noise

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
Attenuation
Internal
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External
Single-mode fibers will not tolerate
a minimum Bend Radius
of less than 6.5 to 7.5 cm
Graded-Index Multimode Fiber will
typically tolerate a minimum bend
radius of not less than 3.8 cm
The fibers commonly used in
customer-premises applications
(62.5-m core) can tolerate a bend
radius of less than an inch (2.5 cm).
(Source: timbercon.com)
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
Dispersion
 Dispersion
occurs when a pulse of light is spread out
during transmission on the fiber
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
Material Dispersion (chromatic
dispersion)





Lasers and LEDs produce a range of
optical wavelengths (a band of light)
rather than a single narrow wavelength
The fiber has different refractive index
characteristics at different wavelengths
and therefore each wavelength will
travel at a different speed in the fiber
Thus, some wavelengths arrive before
others and a signal pulse disperses (or
smears out)
Expressed in picoseconds per kilometer
per nanoseconds (ps/km/n)
Maximum information-carrying capacity
at 1310 nm also known at zerodispersion wavelength
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
Modal dispersion




When using multimode fiber, the
light is able to take many different
paths or “modes” as it travels
within the fiber
The distance traveled by light in
each mode is different from the
distance travelled in other modes
Therefore, some components of the
pulse will arrive before others
Not issue in single mode fiber
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Bandwidth-distance product
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


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 MHz×km.
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 bandwidthdistance product of 500 MHz×km could carry a 500 MHz
signal for 1 km or a 1000 MHz signal for 0.5 km.
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Fiber Optics Connectors, Splices, and Tools
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
Splices v. Connectors
A
permanent join is a splice
 Connectors are used at patch panels, and can be
disconnected
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
Acceptable Losses
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Connectors
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
Rigid Ferrule Connectors
 2.5
ST
mm ferrule
SC
FC
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
Rigid Ferrule Connectors (cont.)
 1.25
mm ferrule
 Small Form Factor
LC
MU
LX-5
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
Obsolete Connectors
 Simplex
SMA
(1-fiber)
D4
Biconic
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
Duplex Connectors
 Old,
FDDI
bulky
ESCON
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MT-RJ
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
Duplex Connectors (cont.)
Opti-Jack
 Newer,
smaller
 Small Form Factor
Volition
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
Duplex Connectors (cont.)
 New,
popular
 Small Form Factor
Duplex LC
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
Duplex Connectors (cont.)
In telecommunications, SC and FC are being replaced by
LC (in the USA) and MU (in other countries)
 In data communications, SC and ST are being replaced
by LC

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Splices
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
Fusion Splicing
 Melts
the fibers together to form a continuous fiber
 Expensive machine
 Strongest and best join for singlemode fiber
 May
lower bandwidth of multimode fiber
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
Mechanical Splicing
 Mechanically
aligns fibers
 Equipment cost is low
 Per-splice cost is high
 Quality of splice varies,
but better than connectors
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Fiber Optic Cable Testing
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Power meter
OLTS
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OTDR
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
OTDR (Optical Time-Domain Reflectometer)
Dead
zone
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
Visual Cable Tracers and Visual Fault Locators
Cable tracer is just a flashlight
 VFL uses an LED or Laser source to get more light into the
fiber

Useful to test a fiber for continuity
 To check to make sure the correct fiber is connected
 With bright sources, you can find the break by looking for light
shining through the jacket


Visible light only goes 3-5 km through fiber
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
Fiber Identifiers
 Bends
the fiber to detect the
light
 Can be used on live fiber
without interrupting service
 Can detect a special
modulated tone sent down a
fiber
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
Optical Continuous Wave Reflectometer
(OCWR)
 Measures
optical return loss (reflectance) of connectors
 Inaccurate on installed systems because it includes
backscatter and all sources of reflectance
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
Microscope
 Used
to inspect fibers and connectors
 Particularly
during epoxy-polish process
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Fiber Optic Installation Safety Rules
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

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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Structured Cabling Architecture
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Unguided Transmission Media
Provides a means for transmitting electromagnetic signals through the air but do not guide
them (wireless transmission)
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Electromagnetic Spectrum for Wireless Communication
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Radio wave and microwave
3 kHz
Infra Red
300 GHz
Light wave
400 THz
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900 THz
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
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
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

the transmitting
antenna puts out a
focused
electromagnetic
beam
the transmitting and
receiving antennas
must be aligned
Dr. Yagi and his Yagi antenna
(example of directional antenna)
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Omnidirectional Antenna
74


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
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

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
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Terrestrial Microwave
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
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.
The Fresnel Zone must be clear
of all obstructions.
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Radius of the first Fresnel zone
R=17.32(x(d-x)/fd)1/2
where d = distance between antennas (in Km)
R= first Fresnel zone radius in meters
f= frequency in GHz
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
Another apps: cellular communication, and LANs
Freq. Band
824 - 894 MHz
902-928 MHz
1.7 - 2.3 GHz
1.8 GHz
2.400-2.484 GHz
2.4 GHz
2.45 GHz
4 - 6 GHz
Infrared
Use
Analog cell phones (AMPS)
License free in North America
PCS digital cell phones
GSM digital cell phones
global license free band
802.11, Lucent WaveLAN
Bluetooth
commercial (telecomm.)
short distance line of sight
Range
Data Rate
20 km per cell 13 kbps/channel
< 1 km per cell
16 kbps/channel
100 m - 25 km
about 10 m
40 - 80 km
5 - 100 m
ET2080 Jaringan Telekomunikasi
2 - 11 Mbps
1 Mbps
100 Mbps
1 Mbps
Transmission characteristics
80

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
ET2080 Jaringan Telekomunikasi
Attenuation
81
 4d 
L  10log

  





2
d is the distance
λ 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)
ET2080 Jaringan Telekomunikasi
82
Satellite Microwave
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83

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
ET2080 Jaringan Telekomunikasi
VSAT
84




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).
ET2080 Jaringan Telekomunikasi
Frequency allocation
85



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
ET2080 Jaringan Telekomunikasi
Fixed satellite service
86

Typical frequency bands for
uplink/downlink
6/4 GHz
8/7 GHz
14/12 GHz
30/20 GHz
usual terminology
C band
X band
Ku band
Ka band
ET2080 Jaringan Telekomunikasi
Mobile satellite service
87

Typical frequency bands for
uplink/downlink
1.6/1.5 GHz
30/20 GHz
usual terminology
L band
Ka band
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Broadcasting satellite service
88

Typical frequency bands for
uplink/downlink
12 GHz
usual terminology
Ku band
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89
Broadcast Radio
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90

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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91



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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94
Infrared
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95

Does not penetrate walls
 no

no frequency allocation issue
 no

security or interference problems
licensing is required
Apps: Infrared Wireless LAN
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96
So..you’ve heard about dB..
What is it?
ET2080 Jaringan Telekomunikasi
Decibel, Gain, dan Loss
97

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
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Decibel in Action
98
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)
ET2080 Jaringan Telekomunikasi
Power Levels in dB
99


Sampai titik ini kita masih melihat penerapan dB
untuk menyatakan perbandingan daya
Bagaimana cara menyatakan level daya absolut
menggunakan dB?
Gunakan suatu daya referensi
ET2080 Jaringan Telekomunikasi




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)
 P 
PdBm  10 log 

1m W 
 P 
PdBW  10 log 

 1W 
ET2080 Jaringan Telekomunikasi
100
101

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 μW.
ET2080 Jaringan Telekomunikasi
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
102
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103



Satuan lain yang biasa digunakan
untuk menyatakan suatu
perbadingan adalah Neper
1 Neper (Np) = 8,685889638 dB
1 dB = 0,115129254 Np
ET2080 Jaringan Telekomunikasi
John Napier or Neper
nicknamed Marvellous Merchiston
(1550, 1617)
Penemu Logaritma

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