Communication Mediums for Signal, ITS, and Freeway Surveillance Systems Final Report (1996) / Chapter Skim
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A.1.2 Fiber Mediums and Terminals
A.1.2 Fiber Mediums and Terminals
Pages 63-131
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From page 63... ...
Long lengths, light weight, and small diameters make optical fiber cable instaDabons much easier and less expensive Can copper. Optical fiber cables can be instaBed wad Be same ~:\NCHRPPhase:~pr NCHRP 3-51 ~ Phase 2 Final Report A1-55
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From page 64... ...
Another advantage is the dielectric nature of optical fiber cables. Since optical fiber is made of glass, it does not conduct electncity, nor is it affected by electromagnetic interference or radio frequency interference.
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From page 65... ...
This can be visualized by the following example: When standing on the shore of a smooth lake with a mountain range in the backdrop, at a certain distance Be mountain range is reflected off Be water's surface; however, Were is a point at which the mountain is no longer reflected and Be bottom of the lake is visible. This is similar to light traveling down an optical fiber.
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From page 66... ...
This gives a simplified reason for the different data rate capacities of different multimode fibers. The greater He number of modes, He greater He modal dispersion among those modes and subsequently He lower the data rate capacity; however, He larger fiber cores (in multimode fibers)
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From page 67... ...
Specifying attenuation is usually done in He windows of operation for He optical fiber. A multimode fiber will have He attenuation specified at 850 rim and 1300 nm, while a single-mode fiber will have attenuation specified at 1310 nm and 1550 nm.
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From page 68... ...
The Bird Thorpe is polarization mode dispersion. Modal dispersion occurs only In multimode fiber while chromatic dispersion occurs in bow single-mode and multimode fiber.
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From page 69... ...
Modal dispersion is the dominant factor in multimode fiber but does not occur in single-mode fiber because there is only one mode. Chromatic dispersion is present in both fiber types.
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From page 70... ...
d. Bandwidth Bandwidth is a measure of Be data rate capacity for multimode fiber.
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From page 71... ...
Table A.~.2.~.~-2 Applications Summary for Single-Mode Optical Fiber Application/ Maximum Data Rate Attenuation Wavelength (nary) Specification Distance (m)
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From page 72... ...
Multimode fiber usually operates in two different windows: 850 nm and 1300 nm. The Milt signal will behave differently at each wavelength.
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From page 73... ...
At high data rates (typically in the Gbps range) copper twisted pair communications can exhibit a bit error rate of lo-6.
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From page 74... ...
This phenomena is common u id copper twisted pair cables but rarely occurs with fiber. 3J Temperature Elects The manufacturing process of optical fiber cable plays a major role in He effect Hat temperature will have on its performance.
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From page 75... ...
There are two distinct optical fiber cable designs that meet the specific demands of the cable environment: loose tube cable and tight buffered cable.
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From page 76... ...
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From page 77... ...
These cables, however, are typically more sensitive to temperature extremes and mechanical disturbances than loose tube cables. As a result, tight buffered cables are generally not recommended for outside plant (interbuilding)
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From page 79... ...
When planning to direct bury an optical fiber cable, the soil condition and local environment are important considerations. If Were is a possibility of rodents gnawing through the cable, the use of armored cable is required; however, placement of a cable encoded in a conduchng medium underground increases We probability of lightning strikes.
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From page 80... ...
d. National Electrical Code Restrictions of He NEC and local building codes must be adhered to when installing optical fiber cable.
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From page 81... ...
Consult Be cable manufacturer for more information on these specific conditions. Use of Unlisted Cables Indoors The National Electrical Code allows He use of unlisted cable in inside plant applications, wig some restrictions.
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From page 82... ...
A transition splice win slightly increase We fiber link loss and may add some cost to the installation. These considerations have to be weighed against the cost of nod metallic conduit or an alternate conduit installation that would be required to install unlisted cable to the desired ternunabon point; however, because Were is a cost difference between loose tube cable and tight buffered cable, the options should be compared.
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From page 83... ...
Meckanicat Splicing A mechanical splice, by comparison, is a junction where two or more optical fibers are aligned and held in place by a self-contained assembly approximately two inches in length. Single-fiber mechanical splices rely upon Be alignment of the outer diameter of Be fibers, making the accuracy of core/cIadding concentricity critical to achieving low splice losses.
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From page 84... ...
. For single fiber fusion splicing, the use of splice trays win organizers designed for use win RTV is recommended.
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From page 85... ...
The chosen splicing method affects both equipment (fusion splicer, mechanical splice fixtures, etc.) and hardware requirements (splice trays, splice closures and centers for storage and protection of Be splices)
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From page 86... ...
Though the ElA=A-568 Commercial Building Wiling Standard allows for a maximum individual splice loss of 0.30 dB for multimode fibers, today's technology makes possible average losses of 0.10 dB or belter. Lastly, Me installer must consider the preference of his customer.
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From page 87... ...
Attaches connector to adapter. Keeps contamination to a minimum and protects polished A fiber optic pigtail is typically a one- or two-fiber cable Hat has been terminated on one end who a fiber connector.
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From page 88... ...
Field Connector~zation General Connectorization Technology With the advent of easy-to-install field connectors and new methods of fanning out loose-tube cables, field connectonzation has become the most common method for tenn~nadng fiber optic cables in the ITS market. Use of field connectonzation throughout We network, is recommended TV He exception of patch cords, equipment cords, or cross-connect jumpers.
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From page 89... ...
fiber, around Me buffer where We fiber enters the connector, and as a bead surrounding the fiber on the endface of the connector. Secondly, He connector endface must be polished.
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From page 90... ...
, no heat generation, very robust polish for 99+% yield, and faster installation. The increase in field installation has become the focus for connector development in recent years.
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From page 91... ...
No-Cure, No-Polish Connectors Advantages: No epoxy, no polish in the field, no consumables, few tools needed, and minimal set-up required. This connector incorporates a fiber stub already bonded into the ferrule in the factory, where He endface of Be ferrule is polished to a PC finish.
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From page 92... ...
Not recommended is We use of fan-out kits for tight-buffered cables when terminated in patch panels or outlets, because We 900 Am buffered fibers provide excellent reliability when protected by the patch panel. There are severe alternatives for fanning out cables; the decision depends on We type of cable used and We application.
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From page 93... ...
If Mere are plans to install a large quantity of optical fiber, Men Me equipment should probably be purchased. Some general purchase cost estimates, depending on Me features, are: fusion splicers, $10k to $40k; outdoors, $10k to $50k; and connector tools kits, $800 to $1500.
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From page 94... ...
It measures He total optical power loss from connector tip to connector rip. This measurement includes fission and mechanical splices as well as connector pairs.
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From page 95... ...
Aniityville, New York /ntroaluction There are a significant number of applications for so-called "Low-end Fiber Optic Transmission Systems" in He emerging [rs market. These systems transmit the common data and video signals used by this marketplace via interference-free, ground-Ioop-free fiber optic cable, and are ~:\NCHRP\Phasc:.~p' NCHRP 3-51 · Phase 2 Final Report A1-87
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From page 96... ...
Wide Bandwidth: The attenuation of fiber optic cable is uniform as a function of distance, not frequency dependent as is the case wad coaxial cable. As a result, high data rates or high frequency signals can be conveyed over long distances without repeaters or special equalizing equipment.
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From page 97... ...
Low-end vs. High-end Fiber Optic Transmission Systems Low-end fiber optic transmission systems primarily consist of point-to-point links, carrying data wad bit rates of 50 to 100 Kb/s or less compared to high-end systems which usually operate at multi-megabit data rates.
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From page 98... ...
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From page 99... ...
This cable is usually constructed along Me lines of similar electrical cable, but with special protective means for Me optical fiber within. For systems requiring transmission over distances of a few kilometers, or where two or more fiber optic cables must be joined, an optical splice is commonly used.
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From page 101... ...
over hand have very small light emoting surfaces and can couple many times more power to Me fiber than L`EDs. They usually require more elaborate circuitry to operate properly.
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From page 102... ...
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From page 103... ...
Rather, the entire optical bandwidth is turned on and off similar to the way early "spark transmitters" in He infancy of radio, turned wide portions of the RF spectrum on and off. Research being done, however, to attempt to fine tune these devices so that, in the future, coherent transmissions as they are caned, may wed be the way the fiber optic field progresses.
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From page 105... ...
There are special coupling gels Hat can be applied between glass surfaces to reduce this loss when necessary. Fiber Characteristics There are three types of fibers in use today: Step Index, Graded Index, and Single Mode.
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From page 106... ...
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From page 107... ...
Multimode fibers are In common use for short and medium length point-topoint transmission systems, while single mode fiber is commonly used for long distance purposes. Multimode fiber is usually convex by L`EDs while single mode fiber is almost always Given by a laser diode.
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From page 108... ...
This produces a "smearing" effect or uncertainty where the start and end of the pulse occur, and it limits He maximum frequency that can be smutted. Typical bandwidths for common fibers range from a few hundred MA per Km for multimode fiber, to thousands of MHi per Km for single mode fiber.
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From page 109... ...
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From page 110... ...
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From page 111... ...
Optical Connectors Fiber optic cable is usually connected to peripheral equipment and to other fibers by means of optical connectors. These connectors are similar to Weir electrical counterparts in function and outward appearance but are actually high precision devices.
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From page 112... ...
The SMA usually has a step-down front barrel and is recommended for connecting fibers to each other or to fiber optic transmission equipment. Two plastic sleeves are supplied with each type connector.
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From page 113... ...
Optical Splices While optical connectors can be used to connect fiber optic cables together, there are over methods that result In much lower losses. Two of the most common and popular are Be elastomenc splice, and the fission splice.
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From page 115... ...
A s~ngle-mode receiver for example, designed to accept He tiny amount of light coming from an 8/10 micron fiber, would overload if connected to He output of a 62.5 micron fiber. By He same token, a 62.5 micron transmitter would only launch a tiny amount of light into an 8/10 micron single mode fiber.
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From page 116... ...
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From page 117... ...
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From page 118... ...
Designing a Fiber Optic System The design of a fiber optic system requires that several primary factors be considered. While not complicated, these determinations are necessary to assure that enough light Will be present at We receiver for proper operation and Rat Be final overall system will operate as desired.
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From page 119... ...
Fiber Optic Parameters: Optical Wavelength Optical Connectors Fiber Core Diameter Cladding Diameter Fiber Cable Length Attenuation (dB/Km) Ambient Requirements Environmental (Underground Conduit)
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From page 120... ...
Committee to standardize commercial camer-to-ca~ner optical interfaces. Single Mode Fiber Optic (SMFO)
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From page 121... ...
In contrast, the DS-n, T1 digital hierarchy evolved to support wire and radio and does not define optical physical transmission standards. SONET is an international standard [called Synchronous Digital Hierarchy (SDH)
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From page 123... ...
Thus, the overhead assignments presented in Figure A.~.2.3-2 are generally assigned for implementation as presented in Figure A.~.2.3-3 A path represents repeaterIess links; a line represents node to node links; and a path represents end-to-end application/user links. Spare communications capacity available for these functions is allocated independent of Me payload.
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From page 124... ...
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From page 125... ...
LLJ of I1J J ~ ct Q X LO x J J Q Y ~ ~_ LLJ 2 · .
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From page 126... ...
on SONET/SDH include: G.702 Digital hierarchy bit rates G.703 Physical/elec~ical characteristics of hierarchical digital interfaces G.707 Synchronous digital hierarchy bit rates G.708 Network node interface for the synchronous digital hierarchy G.709 Synchronous multiplexing structure G.773 Protocol suites for Q interfaces for management of transmission systems c:\NCHRP\Phase2~p ~NCHRP3-51· Phase2FmalReport A1-118
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From page 127... ...
conversely, random arrival, bursty, data has been traditionally served by packet data communication technology. In reality, video has been served by analog technology and has not histonca}Ry represented a digital network load.
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From page 128... ...
/ / 1 ·o D Q en ~ ._ .
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From page 129... ...
ATM we define Public and Private User Network Interfaces ~s)
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From page 130... ...
ITU-T for fixture public multimedia telecommunication services. ATM defines bow ~ infrastructure and end user interfaces and services.
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From page 131... ...
[15] ITU-T Recommendation 1.363, MISDO ATM Adaptation Layer (ML)
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