FIBER OPTIC COMMUNICATION SYSTEM

TOPIC 1 : INTRODUCTION TO FIBER OPTIC COMMUNICATION SYSTEM

Course Learning Outcome

1. Explain clearly the basic concept of fiber optic communication system and system performance(C2)

2. Handle systematically the related communication equipments in performing the assigned practical work(P3)

3. Perform problem solving skill through end of chapter question on any given topic(A2)

Fiber Optic Cable

Fiber Optic

Fiber Optic lamp Profesional lamp – fiber optic

Army Exchange

Endosecopic

Fiber To The Home (FTTH)

Definition

Fiber optics – •A means to carry information from one point to another or serves as transmission medium (optical fiber).•A technology that uses thin strand of glass (or plastic) threads (fibers) to transmit data. •A fiber optic cable consists of a bundle of glass threads, each of which is capable of transmitting messages modulated onto light waves.

History

1870 - John Tyndall

1880 – Alexander Graham Bell

1950 – Development of the fiberscope.

1960 – Line of sight optical

transmission using laser

1966 – Kao and Hockham

1970 – Drs. Robert Maurer,

Donald Keck, and Peter Schultz

2000 and beyond

Fiber optic good

enough?

Why fiber optic?

Advantages?

Disadvantages?

Fiber vs Metallic Cables

• Advantages:– Larger bandwidth – Immune to cross-talk– Immune to static interference– Do not radiate RF– Spark free– No corrosion, more environment resistive.

• Disadvantages– Initial cost of installation high– Brittle (serpih)– Maintenance and repair more difficult and more

expensive

The Advantages of Fiber-Optic Communications System

•The advantages of fiber-optic systems warrant considerable attention.

•This new technology has clearly affected the telecommunications industry and will continue to thrive due to the numerous advantages it has over its copper counterpart.

•The major advantages include.

•Wide Bandwidth•Low Loss Electromagnetic Immunity•Light Weight•Small Size•Noise Immunity and Safety Security•Economic•Reliability

Wide Bandwidth

• Fiber optic communications can run at10 Ghz and have the potential to go as high as 1 Thz (100,000 GHz).

• A 10 Ghz capacity can transmit (per second):– 1000 books– 130,000 voice channels– 16 HTDV channels or 100 compressed HDTV channels.

• Separate Voice, data and video channels are transmitted on a single cable.

Electromagnetic Immunity

• Copper cables can act as an antennae picking up EMI from power lines, computers, machinery and other sources.

• Fiber is not susceptible to Electro-Magnetic Interference and thus no interference allowing error-free transmissions.

Light Weight and Volume

• Comparison:– Fiber – 9lb per 1000 ft. (due mainly to packaging).– Coax – 80lb per 1000 ft.

• Fiber optic cables are substantially lighter in weight and occupy much less volume than copper cables with the same information capacity.

• Fiber optic cables are being used to relieve congested underground ducts in metropolitan and suburban areas.

• For example, a 3-in. diameter telephone cable consisting of 900 twisted-pair wires can be replaced with a single fiber strand 0.005 inch.

• In diameter (approximately the diameter of a hair strand) and retain the same information carrying capacity.

Small Size

• Use where space is at a premium:– Aircraft, submarines– Underground conduit– High density cable areas – Computer centers.

Noise Immunity and Safety

• No electricity thus no spark hazards so can be used through hazardous areas.

• Because fiber is constructed of dielectric materials, it is immune to inductive coupling or crosstalk from adjacent copper or fiber channels.

• In other words, it is not affected by electromagnetic interference (EMI) or electrostatic interference.

Security

• Since fiber does not carry electricity, it emits no EMI which could be used for eavesdropping.

• Difficult to 'tap' – cable must be cut and spliced.• Because light does not radiate from a fiber optic cable, it is

nearly impossible to secretly tap into it without detection.• For this reason, several applications requiring

communications security employ fiber-optic systems. • Military information, for example, can be transmitted over

fiber to prevent eavesdropping. • In addition, metal detectors cannot detect fiber-optic

cables unless they are manufactured with steel reinforcement for strength.

Economics

•Presently, since the cost of fiber is comparable to copper it is expected to drop as it becomes more widely used. •Because transmission losses are

considerably less than for coaxial cable, expensive repeaters can be spaced farther apart. •Fewer repeaters mean a reduction in

overall system costs and enhanced reliability.

Reliability

•Once installed, a longer life span is expected with fiber over its metallic counterparts, because it is more resistant to corrosion caused by environmental extremes such as temperatures, corrosive gases, and liquids.

Disadvantages of Fiber-Optic System

• In spite of the numerous advantages that fiber-optic systems have over conventional methods of transmission, there are some disadvantages, particularly because of its newness.

• Many of these disadvantages are being overcome with new and competitive technology. The disadvantages include:

i. Interfacing Costsii. Strengthiii. Remote powering of devicesiv. Inability to interconnected

Interfacing Costs

• Electronic facilities must be converted in order to interface to the fiber. • Often these costs are initially overlooked. • Fiber-optic transmitters, receivers, couplers, and

connectors, for example, must be employed as part of the communication system. • Test and repair equipment is costly. • If the fiber-optic cable breaks, splicing can be costly and

tedious task. • Manufacturers in this related field however are

continuously introducing new and improved field repair kits.

Strength

•Optical fiber , by itself has a significant lower tensile strength than coaxial cable. •Surrounding the fiber with stranded Kevlar

(A nonmetallic, difficult to-stretch, strengthening material) and a protective PVC jacket can help to increase the pulling strength. •Installations requiring greater tensile

strengths can be achieved with steel reinforcement.

Remote Powering Of Devices

• Occasionally, it is necessary to provide electrical power to a remote device.

• Because this cannot be achieved through the fiber, metallic conductors are often included in the cable assembly.

• Several manufacturers now offer a complete line of cable types, including cables manufactured with both copper wire and fiber.

Inability to interconnect

•Inability to interconnect easily requires that current communication hardware systems be somewhat retrofitted to the fiber-optic networks. •Much of the speed that is gained through optical fiber

transmission can be inhibited at the conversion points of a fiber-optic chain. •When a portion of the chain experiences heavy use,

information becomes jammed in a bottleneck at the points where conversion to, or from, electronic signals is taking place. •Bottlenecks like this should become less frequent as

microprocessors become more efficient and fiber-optics reach closer to a direct electronic hardware interface.

Advantage

Bandwidth · High bandwidth and capacity· Lower signal attenuation (loss)

Immunity to Electrical Noise, Electromagnetic Immunity

· Immune to noise (electromagnetic interference [EMI] · No crosstalk· Lower bit error rates

Signal Security · Difficult to tap· Nonconductive (does not radiate signals)

Size and Weight · Reduced size and weight cables

Overall System Economy · Low overall system cost· Lower installation cost

Reliability · Less restrictive in harsh environments

Disadvantage

Interfacing Costs•High planning, installation, and maintenance cost

Strength •lower tensile strength than coaxial cable

Remote Powering of Devices

•necessary to provide electrical powerto a remote device.• Cannot be achievedthrough the fiber, metallic conductors are often included in the cable assembly.

Inability to interconnect •incompatibility with the electronic hardware systems that make up today's world.

Shaper Decoder

Photocell or light

detector

Amplifier

Original voice or video

Coder and Converter

Light Source Transmitter

Pulses

Information Input (Voice

or video)

Digital data from computer

Fiber Optic cable

Light ON/OFF at rapid rate

Pulses

Digital data to computer

Block Diagram of Fiber Optic Communications

Block Diagram Function

Transmitter

Coder / Converter

Light Source

Fiber Optic Cable

Receiver

Light Detector

ADC

Transmitter Section• The information signals to be transmitted may be voice,

video or computer data. • The first step is to convert the information into a form

compatible with the communication medium. • This is usually done by converting the continuous analog

signal such as voice and video(TV) signal into a series of digital pulses.

Coder or converter

• The information at input is converted into digital signals by coder or converter circuit.

• This circuit is actually ADC (analog to digital converter).

• Thus, it converts analog signals into proportional digital signals.

• If the input signals are computer signals, they are directly connected to light source transmitter circuit.

Light source• The light source block is a powerful light source. • It is generally a FOCUS type LED (Light Emitting Diode) or low

intensity laser beam source (such as Injection Laser Diode-solid state laser) or in some cases infrared beam of light is also used.

• The rate, at which light source turns ON/OFF, depends on frequency of digital pulses.

• Thus, its flashing is proportional to digital input.• In this way, digital signals are converted into equivalent light

pulses and focused at one end of fiber-optic cable.• They are then received at its other end.

Fiber–optic cable

• Fiber–optic cable – when light pulses are fed to one end of fiber-optic cable, they are passed on to other end.

• The cable has VERY LESS attenuation (loss due to absorption of light waves) over a long distance.

• Its bandwidth is large; hence, its information carrying capacity is high.

Receiver section

• Light detector or photocell or photodetector is used to detect light pulses.

• It is a transducer, which converts light signals into proportional electrical signals.

• These signals are amplified and reshaped into original digital pulses, (while reshaping, distortion & noise are filtered out) with the help of shaper circuit.

ADC circuit (Analog to Digital Converter)-

• The signals are connected to decoder. It is actually ADC circuit (Analog to Digital Converter), which converts digital signals into proportional analog signals like voice, video or computer data.

• Digital signals for computer can be directly taken from output of shaper circuit.

0V

5V

Pulses before shaper process

Pulses after shaper process

Application in Communication System

• Analog System

• Digital

Undersea Cable

• Undersea cables are laid on the ocean floor and require several layers of armor to protect the system from damage due to pressure or shifts along the ocean floor.

• The fibers are single-mode optical light guides operating at 1.312 mm. The data rate on each fiber pair is 280Mbps, and repeaters are spaced every 35km.

• Submarine cables are typically buried as they approach shore. This helps protect submarine cables from fishing operations from accidently breaking the submarine cable

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Construction of Undersea Cable

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Fiber Optic World Infrastructure Map

High Definition Television (HDTV)

• The high bandwidth provided by fiber makes it the perfect choice for transmitting broadband signals, such as high-definition television (HDTV) telecasts.

• Analog television is a relatively high bandwidth signal of more than 5 MHz.

• Digital television (in particular HDTV) has bit rates of more than 1.5Gbps.

• High resolution computer graphics can have a bandwidth exceeding 500 MHz.

• All of these television and video applications are ideal for fiber.

High Definition Television (HDTV)

Triple Play Technology

• A triple-play network is one in which voice, video and data are all provided in a single access.

• Most FTTH systems are called "triple play" systems offering voice (telephone), video (TV) and data (Internet access).

• To provide all three services over one fiber, signals are sent bidirectionally over a single fiber using several wavelengths of light.

Triple Play

Ethernet

– Ethernet is a baseband networking technology that has been defined by international standards, specifically IEEE 802.3. A baseband technology devotes the entire bandwidth of the media to one channel

– Is the standard local area network (LAN) access method - used to connect computers in a company or home network as well as to connect a single computer to a cable modem or DSL modem for Internet access.

– It enables the connection of

up to 1024 nodes over coax,

twisted-pair, or fiber optic cable.

Fiber Optic in Local Area Network

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Types of ethernet:Twisted pair : 10Base-T, 100Base-T, 1000Base-T, etcCoax : 10Base5 “thick”, 10Base2 “thin”Fiber : FOIRL, 10Base-F, 100Base-Fx, 100Base-Fx, etc

• The 10, 100 or 1000 in the media type designation refers to the transmission speed of 10 Mbit/s, 100 Mbit/s or 1000 Mbit/s.

• The "BASE" refers to baseband signalling, which means that only Ethernet signals are carried on the medium.

• The TX, FX refer to the physical medium that carries the signal.

• Fiber Optic Inter-Repeater Link (FOIRL) – The most commonly used fiber optic medium type is the link segment.

There are two fiber optic link segments in use today, the original FOIRL segment, and the newer 10BASE-FL segment.

– The original FOIRL specification provided a link segment of up to 1000 meters between two repeaters only. As the cost of repeaters dropped and more and more multiport repeater hubs were used, it became cost-effective to link individual computers to a fiber optic port on a repeater hub.

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• 10BASE-FL (10Mbps, baseband, over fibre optic cable)– The new Fiber Link specifications which replaces the older FOIRL specifications, and is

designed to interoperate with existing FOIRL-based equipment.– It provides for a full duplex fiber optic link segment up to 2000 meters long providing that only

10BASE-FL equipment is used in the segment. If 10BASE-FL equipment is mixed with FOIRL equipment, then the maximum segment length may be 1000 meters.

– A 10BASE-FL segment may be attached between two computers, or two repeaters, or between a computer and a repeater port.

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• 10BASE-FB – The Fiber Backbone link segment system. The 10BASE-FB specifications

describe a special synchronous signaling backbone approach that allows the limit on the number of repeaters that may be used in a given Ethernet system to be exceeded. 10BASE-FB links do not attach to computers or end nodes, and are only used to link special 10BASE-FB repeater hubs together in a large repeated backbone system. 10BASE-FB links may be up to 2000 meters in length.

• 100BaseX– The 100BaseX (Fast Ethernet) standard is an extension of the existing

Ethernet standard. It runs on UTP Category 5 data grade cable and uses CSMA/CD in a star wired bus topology, similar to 10BaseT where all cables are attached to a hub.

• 100Base-Sx– 100BASE-SX standard was released as a low cost upgrade in performance

from 10BASE-FL systems. It utilizes 850nm devices and ST connectors. Segment length are limited to 300m

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• 100Base-BX10– 100BASE-BX10 supports single-mode, single fiber and a signaling

speed of 125 Mbd. It also supports greater than a 10 km span. The optical output is -14 dBm with a sensitivity of -29.2 dBm.

• 100Base-Lx10– 100BASE-LX10 is a version of Fast Ethernet over two single mode

optical fiber.– It has a nominal reach of 10 km and a nominal wavelength of

1310 nm. – The 100BASE-LX10 support is for single-mode, dual fiber connections

at a signaling speed of 125 Mbd.

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• Gigabit Ethernet (1 to 100 Gigabit Ethernet)

– Gigabit Ethernet is the latest version of Ethernet and based on the same Ethernet standard but 10 times faster than Fast Ethernet and 100 times faster than Ethernet. It also supports additional features that accommodate today's bandwidth-hungry applications and match the increasing power of the server

– Gigabit Ethernet requires the use of optical fiber on all connections beyond 100 meters due to the extreme difficulty in transmitting very narrow pulses over copper media and having them recognizable at a receiver.

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Example of Gigabit Ethernet Scenario

Existing Ethernet LANs with 10 and 100 Mbps cards can feed into a Gigabit Ethernet backbone.

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• Fiber Distributed Data Interface (FDDI)

– FDDI is a set of ANSI and ISO standards for data transmission on fiber optic lines in a local area network (LAN) that can extend in range up to 200 km.

– The FDDI protocol is based on the token ring protocol. – FDDI local area network can support thousands of users.

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– FDDI network contains two token rings, one for possible backup in case the primary ring fails. The primary ring offers up to 100 Mbps capacity. If the secondary ring is not needed for backup, it can also carry data, extending capacity to 200 Mbps.

Application in MAN & WAN

• SONET (Synchronous Optical Networking) and SDH (Synchronous Digital Hierarchy) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers or highly coherent light from light-emitting diodes (LEDs).

• At low transmission rates data can also be transferred via an electrical interface.

• The method was developed to replace the Plesiochronous Digital Hierarchy (PDH) system for transporting large amounts of telephone calls and data traffic over the same fiber without synchronization problems.

• SONET and SDH use different terms to describe the three layers. SDH uses the terms path, multiplex section, and regenerator section while SONET uses the terms section, line, and path.

• The Synchronous Optical Network (SONET) and Synchronous Digital Hierarchy (SDH) are a set of related standards for synchronous data transmission over fiber optic networks that are often used for framing and synchronization at the physical layer.

• SONET is the United States version of the standard published by the American National Standards Institute (ANSI). SDH is the international version of the standard published by the International Telecommunications Union (ITU).

• SONET/SDH can be used in an ATM or non-ATM environment. Packet Over SONET/SDH (POS) maps IP datagrams into the SONET frame payload using Point-to-Point Protocol (PPP).

• The following table lists the hierarchy of the most common SONET/SDH data rates:

SONET Signal Bit Rate (Mbps) SDH Signal SONET Capacity SDH Capacity

STS - 1, OC - 1 51.84 STM - 0 28 DS - 1s or 1 DS - 3 21 E1s

STS - 3, OC - 3 155.52 STM - 1 84 DS - 1s or 3 DS - 3s 63 E1s or 1 E4

STS - 12, OC - 12 622.08 STM - 4 336 DS - 1s or 12 DS - 3s 252 E1s or 4 E4s

STS - 48, OC - 48 2,488.32 STM - 16 1,344 DS - 1s or 48 DS - 3s 1,008 E1s or 16 E4s

STS - 192, OC - 192 9,953.28 STM - 64 5,376 DS - 1s or 192 DS - 3s 4,032 E1s or 64 E4s

STS-768, OC-768 39,813,120 STM-256 21,504 DS - 1s or 768 DS - 3s 16,128 E1s or 256 E4s

SONETOpticalCarrierLevel

SONETFrameFormat

SDH leveland Frame

Format

Payloadbandwidth

(Kbit/s)

Line Rate(Kbit/s)

OC-1 STS-1 STM-0 50,112 51,840

OC-3 STS-3 STM-1 150,336 155,520

OC-12 STS-12 STM-4 601,344 622,080

OC-24 STS-24 - 1,202,688 1,244,160

OC-48 STS-48 STM-16 2,405,376 2,488,320

OC-192 STS-192 STM-64 9,621,504 9,953,280

Table : SONET/SDH Data Rate

SONET/SDH Designations and bandwidths

FTTx (Fiber-to-the-x)• is a generic term for any network architecture that uses

optical fiber to replace all or part of the usual copper local loop used for telecommunications.

It describes the fiber optic network for the "last mile" of the telecom connectivity between the communications provider and the customer.

The four technologies, in order of an increasingly longer fiber loop are: • Fiber to the Node (‐ ‐ ‐ FTTN) or Fiber to the Cabinet ‐ ‐ ‐

(FTTCab) • Fiber to the Curb (‐ ‐ ‐ FTTC), • Fiber to the Building (‐ ‐ ‐ FTTB) • Fiber to the Home (‐ ‐ ‐ FTTH) or Fiber-to-the-Premise

(FTTP). Both are often used interchangeably

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FTTN - fiber is terminated in a street cabinet up to several kilometers away from the customer premises, with the final connection being copper.

FTTCab - this is very similar to FTTN, but the street cabinet is closer to the user's premises; typically within 300m.

FTTC - fiber running directly from the central Office to the outdoor shelters on curbs near homes or any business environment.

FTTB - fiber reaches the boundary of the building, such as the basement in a multi-dwelling unit, with the final connection to the individual living space being made via alternative means.

FTTH - fiber reaches the boundary of the living space, such as a box on the outside wall of a home.

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FTTP - this term is used in several contexts: as a blanket term for both FTTH and FTTB, or where the fiber network includes both homes and small businesses.

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New technology of FTTx

• It is not a surprise when came to know from Draka that they had developed optical fiber cable and connectors that will take the optical communication signals to the house boats floating in Amsterdam lakes!

• Before naming that technology we expect the announcement of a new technology: FTTM – Fiber to the Moon!

If Draka can take fiber to the house boats and Google can aim moon, why Fiber to the Moon – FTTM should remain only as a wild dream?

FTTH

FTTH

FTTB

FTTB

FTTC

FTTC

Quick Test

1. Define fiber optic? 2. The advantages of fiber optic, overcome its

disadvantages. Explain the advantages and disadvantages of fiber optic.

3. Draw the block diagram of fiber optic communication system.

4. State the function of each block in the diagram.

• Which of the following answer, describe the application of fiber optic in communication system.i. Triple Play Systemii. Undersea Communication Cableiii. Digital Transmission Systemiv. Weather forecast System

Quick Test

• State TWO (2) application of fiber optic in Metropolitan Area Network (MAN)?

• FTTH is the application of fiber optic in Metropolitan Area Network (MAN). State the application of FTTH nowadays.

Quick Test