jartel-3 guided transmission media

8/18/2019 Jartel-3 Guided Transmission Media

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JARINGAN TELEKOMUNIKASI

Nanang IsmailUIN SGD


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Tipe-tipe Media TransmisiGuided 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 MediaWAVES ARE GUIDED ALONG SOLID MEDIUM

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Model Saluran Transmisi

Menurut Telegrapher's Equations, suatu saluran transmisi terdiri dari serangkaiankomponen dua kutub 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 TembagaPaling lama dan sudah biasa digunakanKelemahan: redaman tinggi dan sensitif terhadap interferensi

Redaman pada suatu kabel tembaga akan meningkat bila frekuensidinaikkan

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

Tiga jenis kabel tembaga yang biasa digunakan:Open wireCoaxial

Twisted Pair

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Open wireSudah jarang digunakan

Kelemahan:◦ Terpengaruh kondisi cuaca dan

lingkungan◦ Kapasitas terbatas (hanya

sekitar 12 kanal voice)

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70 miles open wire from Hawthorne to TonopahPhotograph 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


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Twisted pair

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

Pada suatu bundel twisted pair (lebih dari satu pasang), twistlength (twist rates) masing-masing pasangan dibedakan untukmencegah crosstalk antar pasanganPengiriman sinyal pada twisted pair menggunakan “balancesignaling” untuk mengeliminasi pengaruh interferensi (noise)

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Balance SignalingA balanced transmission line is one whose currents are symmetric withrespect to ground so that all current flows through the transmission line andthe load

◦ none through ground

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

It is also called differential signaling

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Source: York County Amateur Radio Society


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

Notice that the currents are equal and opposite and that thetotal 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

Example #1


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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

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 #3V = +6 VDC

V = -6 VDC

I = 20 mA

I = -25 mA


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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 (balance-unbalance)

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Twisted pairs TypesUnshielded 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 newtechniques, long-range Ethernet and DSL, operating at 10Mbps and even faster, canbe 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 supportsup 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 and can carry up to 16Mbpsover 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 and can handle up to 100Mbpsover a range of 330 feet (100m). Cat 5 cable is typically used for Ethernet networksrunning 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.

Category 5e - Cat 5e (enhanced) operates over a bandwidth of 100MHz on UTP, with arange 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 morestringent standards.

◦ Category 5e is recommended for all new installations and was designed for transmission speeds ofup 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 and supportsup 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 5/5eand Cat 3 cable standards.

◦ Cat 6 features more stringent specifications for crosstalkand 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 preventelectromagnetic interference.Because the shielding is made of metal, it may also serve as aground.

However, usually a shielded or a screened twisted pair cablehas a special grounding wire added called a drain wire .This shielding can be applied to individual pairs, or to thecollection of pairs.

When shielding is applied to the collection of pairs, this isreferred 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 UTPcable (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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Screened shielded twisted pair (S/STP orS/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 7Cat 7 is specified in the frequency range of 1MHz to600MHz.◦ ISO/IEC11801:2002 Category 7/Class F is a cable standard for Ultra

Fast Ethernet and other interconnect technologies that can be madebackward compatible with traditional Cat 5 and Cat 6 Ethernet cable.

◦ Cat 7, which is based on four twisted copper pairs, features evenmore stringent specifications for crosstalk and system noise than Cat6.

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

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Copper Cable Transmission Characteristics

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Crosstalk

Whenever a current flows through a conductor, a magnetic field is set up around the conductor in adirection given by the right-hand corkscrew rule

Because the signal on a transmission line is an electro-magnetic wavefront propagating along the line,current flowing in one direction in one conductor flows in the opposite direction in the other conductor.

The magnetic field around the right hand conductor flows anti-clockwise.

At some distance from the line the effects of the fields cancel out, but near to the conductors the fields re-inforce, and are in the same direction throughout the length of the transmission line

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Source:

magnetic fields(crosstalk)


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If we now bring another pair of conductors close to the first, the re-inforcingfield created by the currents flowing in the first line cuts through the plane ofthe new line, and this has the effect of inducing current into the new line.

We have created a very long narrow transformer, and have caused a couplingbetween the two lines which is crosstalk

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Now let us see what happens if we twist the interfering pair.

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The magnetic fields still rotate around the conductors in the same directions, and they still re-inforce near

to the pair. But now they are not pointing in the same direction all along the length of the line. At everytwist, the direction is reversed, so the net effect on the adjacent pair is cancelled out.

If the second pair is twisted as well, the crosstalk is reduced still further, provided that the twists in thetwo pairs are not in phase with each other. This is an important consideration when designing andmanufacturing cables.

By twisting the pairs we have reduced the potential for crosstalk.


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External noise pickup is ideally the same on the twoconductors (zero difference) and ignored by the receiverresulting in total noise suppressionOnly the differential (opposite on the two conductors) datasignal is let into the receiver

◦ +2.5V 1 + N - ( -2.5V 2 + N ) = +5.0V Diff

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External noise pickup on either of the two conductors cannot beneutralized and will interfere with desired signal received

The differential (opposite on the two conductors) data signal and Noiseis let into the receiver

◦ +2.5V 1 + N - ( -2.5V 2 ) = +5.0V Diff + N

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Crosstalk MeasurementCrosstalk is measured in two ways and resulted in NEXT (Near-endcrosstalk) and FEXT (Far-end crosstalk)

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PSNEXTPower sum NEXT (PSNEXT) isactually a calculation, not ameasurement

PSNEXT is a measure of differencein signal strength betweendisturbing pairs and a disturbedpair

A larger number (less crosstalk) ismore desirable than a smallernumber (more crosstalk)

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FEXT

Far End Crosstalk (FEXT) is measured at both ends of a cable, bytransmitting a signal into one pair at one end and measuring the resultingsignal power on an adjacent pair at the other end.The FEXT is given by

◦ FEXT = POUT/P IN = 10 log (P OUT/P IN) dBA higher FEXT values correspond to better cable performance

FEXT is highly influenced by the length of the cable, since the signalstrength inducing the crosstalk is affected by how much it has beenattenuated from its source

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Equal Level Far End Crosstalk (ELFEXT)

ELFEXT is a calculated result, rather than a measurementIt is derived by subtracting the attenuation of the disturbing pairfrom the Far End Crosstalk (FEXT) this pair induces in anadjacent pair.ELFEXT loss is critical when two or more wire-pairs carry signalsin the same direction.50 m link example:

◦ For FEXT = 45 dB and Attenuation = 11 dB, then ELFEXT = 45 - 11 = 34 dB

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Power Sum ELFEXT (PSELFEXT)

PSELFEXT is the computed effect of disturbingpairs upon the disturbed pair with respect tothe far end of the cable

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Nominal velocity of propagation (NVP)

NVP refers to how quickly signals travel in a cable expressed as a percentagerelative to the speed of light in vacuum

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Propagation DelayPropagation Delay is the time required for data signal to travel from itssource to its destination over a single pairIf we have more than one pair, for example bellow we have four pairs, thensince each pair has different twist rates, each pair length is different

◦ Therefore, the propagation delay in a 4 pair cable is different for each pair

This variance (delay skew) should not exceed 50 nS on any link segment upto 100 meters

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Delay SkewDelay skew is a calculation, derived from the propagation delayDelay Skew is the difference in Propagation Delay time between thefastest (shortest) and slowest (longest) pairs within the same cablesheathWell-constructed and properly installed structured cabling should havea skew less than 50 nanoseconds (nSec) over a 100-meter linkLower skew is betterAnything under 25 nSec is excellent.Skew between 45 and 50 nanoseconds is marginally acceptable

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Insertion Loss (Attenuation)Attenuation is the loss of electrical power as signal travelsalong a cable

Any passive device inserted in a circuit, such as a cables, has anattenuation and so it is also called insertion loss

Insertion loss (expressed in dB) measures the amount ofenergy that is lost as the signal arrives at the receiving end ofthe cabling linkInsertion loss also increases with the length of the linkThe smaller insertion loss measurement values (expressed indB) are better than larger values.

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Depending upon the gauge of wire used in constructing thepairs, 24 gauge wires will have less attenuation than thesame length 26 gauge (thinner) wires.◦ American Wire Gauge (AWG) is a standardized method of measuring

wire diameter

◦ As the AWG number increases, the wire diameter decreases

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Attenuation to Crosstalk Ratio(ACR)/Headroom

The difference between NEXT (in dB) and Attenuation (in dB)ACR is a very good indicator of the real transmission quality of the linkThe higher the ACR the better as it implies that the desired signal is not being so severelyattenuated that the effect of crosstalk noise will become too significantIn communication channels it is generally considered that a positive value of ACR is required forsuccessful error free transmission

Minimum value of ACR of the cabling system in the applicable bandwidth should be greater than10 dB

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Cable engineering for local area networks By Barry J. Elliott


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Return LossReturn Loss (RL) is a measure of the reflected energy from a transmitted signal at all locationsalong the link and is expressed in decibel (dB).

A higher RL values correspond to better cable performance

Mismatches predominantly occur at locations where connectors are present, but can also occur incable where variations in characteristic impedance along the length of the cable are excessive

Other RL factors include manufacturing tolerances, installation and termination methods such askinks in the cable, poor cable construction, improper termination or a compressed cable

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Return loss dB = 20 log (Z n + Z 0 )/(Z n − Z 0 )Zn = line impedanceZ0 = characteristics impedance


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Example:◦ Consider the following network’s output port and its termination. The characteristic impedance ( Z 0 ) of

the output of the network is 600 . We have terminated this network in its characteristic impedance(Z0). Let us assume for this example that it is 600 . How well does the network’s output port match itscharacteristic impedance?

◦ Return loss tells us this◦ First let us suppose that Zn is exactly 600 . If we substitute that in the equation, what do we get? Wehave then in the denominator 0. Anything divided by zero is infinity. Here we have the ideal case, an

infinite return loss; a perfect match.◦ Suppose Zn were 700 . What would the return loss be? We would then have:◦ Return lossdB = 20 log(700 + 600)/(700 − 600) = 20 log(1300/100) = 20 log 13 = 22.28 dB .

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Good return loss values are in the range of 25 dB to 35 dB

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DC loop resistanceDC loop resistance for copper conductors, the followingformula is applicableRDC = 0.1095/d 2◦ RDC = loop resistance ( /mi)◦ d = diameter of the conductor (inches)

Example: If we want a 17-mile loop, allowing 100 per mileof loop (for the 1700- limit), what diameter of copper wirewould we need?Ans:◦ 100 = 0 .1095/d ◦ d = 0.1095/100 = 0.001095◦ d = 0.0331 inches or 0.84 mm or about 19 gauge

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Twisted Pair ConnectorsKabel twisted pair untuk komputer menggunakan konektor RJ45 (8 pin)Kabel twisted pair untuk telepon menggunakan konektor RJ11

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Cable Fire Rating

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Cable Comparison

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Cable Legend

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Optical Fiber

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Optical Fiber AdvantagesWeight 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 areactually 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

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 andExternal Pressures (UV Cured Acrylate)

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Mengapa cahaya bisa bergerak sepanjangserat optik?

Karena ada fenomena TotalInternal Reflection (TIR)

TIR dimungkinkan denganmembedakan indeks bias (n)

antara core dan clading◦ Dalam hal ini n core > ncladding◦ Memanfaatkan hukum Snellius

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Remembering Snellius

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n core > n cladding


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Critical angle◦ At the critical angle we know that q ² equals 90° and sin 90° = 1 and so

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

(Total Internal Reflection)

where the angle q 1 is greater than the critical value the ray isrefracted into the cladding and will ultimately be lost outsidethe fiber


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Numerical Aperture (NA)

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Light ModesCan be as few as one mode and as many as tens of thousands of modes

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Fiber Transmission Windows


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Fiber Transmission Windows(Bands)

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Transmitter Light SourcesLight 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

VCSEL’s–Vertical 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 switching –Most expensive

(especially DFB)

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Salah satu cara untuk mengidenifikasikonstruksi kabel optik adalah denganmenggunakan perbandingan antaradiameter core dan cladding. Sebagaicontoh adalah tipe kabel 62.5/125.Artinya diamater core 62,5 micron dan

diameter cladding 125 micronContoh lain tipe kabel:50/125, 62.5/125dan 8.3/125

Jumlah core di dalam satu kabel bisaantara 4 s.d. 144

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Klasifikasi Serat Optik

Berdasarkan mode gelombang cahaya yangberpropagasi 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

Pada step index fiber, perbedaan antara index biasinti dengan index bias cladding terjadi secaradrastis

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Pada gradded index fiber, perbedaan index bias bahan dari inti sampaicladding 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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Singlemode Optical Fiber

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If a short pulse of light from a source such as a laseror an LED is sent down a narrow fiber, it will bechanged (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 waysThe reasons for the above are as follows:

◦ Attenuation◦ Maximum Power◦

Polarization◦ Dispersion◦ Noise

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AttenuationThe pulse will be weaker because all glassabsorbs light

◦ More accurately, impurities in the glass canabsorb light but the glass itself does notabsorb light at the wavelengths of interest

In addition, variations in the uniformity ofthe glass cause scattering of the lightBoth the rate of light absorption and theamount of scattering are dependent on thewavelength of the light and thecharacteristics of the particular glassMost light loss in a modern fiber is causedby scattering

So, internally, attenuation is caused by :◦ Absorption◦ Scattering

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External factors ofattenuation◦ Micro Bending

◦ Caused by small deviationsin fiber core

◦ Macro Bending

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It can cause microbending also


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Maximum PowerThere is a practical limit to the amount of power that can be sent on afiber

◦ This is about half a watt (in standard single-mode fiber) and is due to anumber of non-linear effects that are caused by the intense electromagneticfield in the core when high power is present

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PolarizationOne way of thinking about light is toconceive of it as an electromagneticwave just like a radio wave

◦ An electromagnetic wave consists oftwo fields: An electric field and amagnetic field

◦ Both of these fields have a directionand a strength (or amplitude)

◦ Within the electromagnetic wave thetwo fields (electric and magnetic) areoriented at precisely 90° to one another

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The orientation of theelectromagnetic field is referred toas “polarization”

The established convention whendiscussing polarization of

electromagnetic fields is to refer tothe direction of the electric fieldwith respect to some plane orboundary towards which the waveis headed

The field orientations can alsochange over time and we get whatare called “circular” and “elliptical”polarizations

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LinearCircular Elliptical


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Conventional communication optical fiber is cylindrically symmetric butcontains imperfections

Light travelling down such a fiber is changed in polarization

Note: Light that comes from a mixture of all the possible polarizations(generated by, say, a light bulb) is called unpolarized

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DispersionDispersion occurs when a pulse of light is spread out duringtransmission on the fiber

◦ A short pulse becomes longer and ultimately joins with the pulse behind,making recovery of a reliable bit stream impossible

There are many kinds of dispersion but the most important three arebelow:

◦ Material dispersion (chromatic dispersion)◦ Modal dispersion◦ Waveguide dispersion

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Material Dispersion (chromatic dispersion)

Both lasers and LEDs produce a range ofoptical wavelengths (a band of light) ratherthan a single narrow wavelengthThe fiber has different refractive indexcharacteristics at different wavelengths andtherefore each wavelength will travel at a

different speed in the fiberThus, some wavelengths arrive before othersand a signal pulse disperses (or smears out)

Expressed in picoseconds per kilometer pernanoseconds (ps/km/n)

Maximum information-carrying capacity at1310 nm also known at zero-dispersionwavelength

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Modal dispersion

When using multimode fiber,the light is able to take manydifferent paths or “modes” as ittravels within the fiberThe distance traveled by lightin each mode is different fromthe distance travelled in othermodesTherefore, some componentsof the pulse will arrive beforeothersNot issue in single mode fiber

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Waveguide dispersionWaveguide dispersion is a very complex effect and is caused by theshape and index profile of the fiber core

However, this can be controlled by careful design and, in fact,waveguide dispersion can be used to counteract material dispersion

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NoiseFiber doesn't pick up noise from outside the system

However, there are various kinds of noise that can come fromcomponents within the system itself (we will not cover this, you cantake Optical Communication System course to learn it)

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Bandwidth-distance product

Because the effect of dispersion increases with the lengthof the fiber, a fiber Information carrying capacity is oftencharacterized by its bandwidth-distance product, oftenexpressed in units of MHz×km.

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

For example, a common multimode fiber with bandwidth-distance 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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Optical Fiber Selection Table

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Optical Fiber Connectors

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Fiber Optic Installation Safety


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RulesKeep all food and beverages out of the work area. If fiber particles are ingested they can causeinternal hemorrhagingWear 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 meansAlways wear safety glasses with side shields and protective glovesTreat 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 lightsource at the other end

◦ Use a fiber optic power meter to make certain the fiber is dark. When using an optical tracer or continuitychecker, look at the fiber from an angle at least 6 inches away from your eye to determine if the visible light ispresent..

Only work in well ventilated areasContact 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 beenthoroughly washedKeep 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 doneDo not smoke while working with fiber optic systems.

Source: http://www.jimhayes.com/

jartel-3 guided transmission media

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