fiber 1

What is the purpose of grounding to earth?

(1) To protect against the adverse effects of lightning; (2) assist in the reduction of static; and (3) bring a zero-voltage reference to system components.

The 10G-EPON access architecture supports two data rates in the upstream: what are they?

1 Gbps and 10 Gbps.

What is one of the requirements that have been identified for next-generation access network architectures?

10 Gbps downstream data rate capacity.

What is the minimum amount of slack that must be provided for splicing fiber-optic cable in underground installations?

15 meters on both the inbound and outbound span.

How many meters of slack cable are used in an aerial installation, typically?

15-25 meters.

In networks transporting data rates that are higher than _____, Fabry-Perot (F-P) lasers are considered inadequate.

2.5 Gbps

What is the maximum data rate the XG-PON2 access architecture supports in the upstream?

2.5 Gbps.

What is the minimum clearance in the middle of a cable span between the power's secondary conductor and the fiber-optic cable belonging to a broadband cable operator?

30 inches.

What is one example of a stipulation in a franchise agreement that would affect network design?

A 100% fiber-optic network.

What is channel bonding?

A 3.0 revision to Data Over Cable Service Interface Specification (DOCSIS) that significantly increases upstream and downstream transport data rates.

What does a point-to-multipoint (P2MP) topology consist of?

A P2MP topology consists of a host element connected through a splitter or optical coupler to two or more receiving elements.

What can be attached to the pulling line to prevent the fiber-optic cable from twisting during installation?

A break-away swivel.

What are the two primary components of an in-line optical connector?

A connector body (which includes two ferrules and two keying mechanisms) and a mating adapter.

What are some prerequisites before performing a fusion splice of optical fibers?

A controlled environment such as a splicing van, trailer, or tent and a stable work surface that is large enough to accommodate the fusion splicer, tools, and the splice closure.

Where would you expect to install a mid-entry splice in a fiber-optic cable network?

A location where a select number of optical fibers need to be spliced, and the remaining buffer tubes and fibers remain untouched.

What is MPEG (Moving Picture Experts Group)?

A universally accepted standard for digital television, first released in 1992.

What is the difference between the fiber-to-the-node (FTTN) and fiber-to-the-curb (FTTC) topologies?

An FTTC is allowed a smaller number of RF amplifiers between the optical fiber and the customer premises.

What is a positive-intrinsic-negative (PIN) diode?

An optical detector with current flow that is linear to the intensity of light photons, with one electron/hole pair created for every absorbed photon until saturation.

What can be used as a pulling line in a conduit?

An unused cable that is already installed in the conduit.

Where would you expect Fresnal reflections to occur in a fiber-optic network?

At the connectors and splices where the signal source is entering or exiting the cable.

Why are Velcro straps preferred over standard plastic tie wraps when bundling pigtails for storage in a splice panel?

Because Velcro straps are removable and can hold the pigtails together without placing undue strain on the optical fibers.

What is the purpose of buffer tubes in fiber-optic cable?

Buffer tubes protect and separate the optical fiber in smaller bundles.

How should surface particulates usually be removed from optical connectors?

By using a compressed-air cleaner designed for optical connectors.

What are two critical factors for a successful installation of fiber-optic cable?

Cable pulling tension and cable bend radius.

What is one reason why broadband cable operators install fiber-optic cable in stages instead of changing the infrastructure all at once?

Changing the infrastructure all at once would cause too many service disruptions.

What is an example of transport media in a telecommunications network?

Coaxial cable.

Which of the following statements about backup systems is not true?

Commercial power generators are available in single-, two-, or three-phase units.

In an optical node, what are common voltages produced by DC power supplies?

Common voltages produced by DC power supplies include +5, +12, and +24 VDC.

What functions does the detector in an optical receiver perform?

Conversion of an optical carrier to an electrical signal, and demodulation of the modulated optical carrier.

What are the main elements of an optical transmitter?

Data encoder/modulator, electrical interface, laser, optical interface.

What are the main elements of an optical receiver?

Demodulator, electrical interface, optical detector, optical interface.

Which type of map contains node information?

Design map.

Which type of optical detection involves a photodiode that converts the light waves to an electrical signal that varies in proportion to intensity changes in the light waves?

Direct.

Which type of star topology used in a passive optical network (PON) places the PON splitters into fiber access terminal (FAT) located deep in the network and closer to the customer premises than the centralized split?

Distributed star.

Which acceptance-testing stage includes adjusting attenuation levels for the first time?

During equipment activation.

Coarse wavelength division multiplexing (CWDM) applications were expanded to include use in large metropolitan networks, utilizing wavelengths in what band?

E-band.

Which type of optical amplifier produces no measurable distortion to the modulated light wave?

Erbium-doped fiber amplifiers (EDFA).

Which type of passive optical network (PON) architecture was formed to develop a cost-effective, high-bandwidth, easy-to-provision solution for connecting businesses, schools, libraries, and customer local area networks to the public Internet?

Ethernet PON (EPON).

What information should always be included in fiber-optic network documentation?

Fiber assignments.

What type of fiber-to-the-x (FTTx) topology does a passive optical network (PON) use to make a point-to-multipoint (P2MP) fiber-optic cable connection between the broadband cable headend and the customer premises?

Fiber-to-the-premises (FTTP).

Besides protection, what else must the coating on an optical fiber do?

Function over a wide temperature range; be compatible with cable gels; adhere to the glass cladding over the lifetime of the cable; and be mechanically strippable for splicing operations.

Which optical splitter package is similar in appearance and size to a standard fusion splice protector?

Fused biconical taper (FBT).

Which type of optical coupler provides the least amount of insertion loss?

Fused.

What do diameter differences between spliced fibers look like on an optical time domain reflectometer (OTDR)?

Gain in one direction and high loss in the opposite direction.

Which type of passive optical network (PON) access architecture replaced asynchronous PON (APON)?

Gigabit-capable PON (GPON).

What is one element used in the transmission and reception of dense wavelength division multiplexing (DWDM)?

High-quality, cooled distributed feedback lasers.

The number of rectifiers used in a DC power plant design

Is dependent upon the load placed on the system.

Which of the following is true of a node using centralized power?

It can provide sufficient power for a fiber-optic node, including outside plant amplifiers and customer premises network interface devices (NID) for telephony service.

What is the current standardized outside diameter (OD) of the cladding of single-mode fiber?

It is 125 µm, with an accuracy of ±1 µm.

What is digital modulation?

It is the interruption of light waves in a coded sequence.

In what type of installation is wide wavelength division multiplexing (WWDM) used?

It is used in passive optical networks.

Why might a technician who is troubleshooting an outage in an optical network want to refer to the network's as-built documentation?

It will help the technician determine specific cable lengths.

Which answer best describes network topology?

It's a sub-layer of network architecture that describes the physical and logical configuration of connected elements between the signal source and the network termination elements.

What is a design option for a broadband cable network that maximizes the use of resources?

Leasing spare fibers.

When preparing fiber-optic cable for connection to a patch panel, how much buffer tube and fiber slack should be provided?

Leave enough slack in the buffer tubes to allow the splice trays to reach the splicing equipment and enough fiber slack to store on individual trays for later additions, moves, and changes.

What are the factors that contribute to an optical receiver's sensitivity?

Noise, responsivity, response time, linear response, back reflection, and optical detector material.

What does the amplification process in an avalanche photodiode (APD) introduce into the electrical output of an optical detector?

Noise.

What happens if the optical signal exceeds the maximum specified input power into a photodetector?

Nonlinear operation resulting in distortion, data errors, and signal loss.

Which element of a passive optical network (PON) uses a Bragg grating filter?

Optical line terminal (OLT).

Which component of an optical modulation system contains an optical detector and a demodulator?

Optical receiver.

Which component of a digital optical network is used to receive digital modulation light waves and convert them to an electrical signal?

Optical transponder.

What is a benefit of using a point-to-point (P2P) topology instead of a point-to-multipoint (P2MP) topology?

P2P topologies are more secure than P2MP topologies.

Which statement about pigtails used for optical fiber terminations is true?

Prior to splicing, pigtails should be labeled to correspond with the correct color code and patch panel designation.

What is it about radio frequency over glass (RFoG) that made broadband cable operators envision using it to make a seamless transition from the legacy hybrid fiber/coax (HFC) architecture over to a gigabit-capable passive optical network (GPON) or Ethernet passive optical network (EPON)?

RFoG does not require any changes to be made to the physical structure of the network, which is cost-effective.

In an optical network, what is reflectance?

Reflectance is the reflected light from a single Fresnel reflection event.

Internet protocol (IP) telephony systems

Require a call management server, media gateway, signaling gateway, billing system, and cable modem termination system (CMTS).

Radio frequency over glass (RFoG), fiber-to-the-x (FTTx) systems

Require consideration of how and who will provide AC power at the customer location.

How are optical splices secured in a splice tray?

Retaining clips hold optical splices in place in a splice tray.

What is a consideration for the use of ribbon fiber?

Ribbon fiber requires mid-entry splice techniques.

Which type of network topology has been focused primarily on alternative routing around cities and industrial areas?

Ring.

Which of the following is true about the synchronous optical network (SONET) transmission standard?

SONET is the international standard used for telephony applications.

When installing fiber-optic cable over coaxial cable, what should be done at the coaxial cable expansion loops?

Secure the fiber-optic cable to the strand across the coaxial cable expansion loops using plastic cable ties or support straps.

In a centralized server video-on-demand (VOD) architecture,

Servers store VOD content at each headend and hub location.

Which category of fiber-optic cable design uses some variation of the star topology, typically?

Signal distribution.

What information can be derived from recording the sequential marking information printed on a fiber-optic cable jacket in the "as-built" documentation?

Slack and splice locations.

In what applications is a splice closure used?

Splice closures are used to protect optical fibers and splices against a full range of environmental changes in aerial installations or below ground in vaults.

What is the purpose of splice trays inside splice closures?

Splice trays are designed to provide protection for mechanical splices, fusion splice protectors, and optical splitters as well as provide storage for the required fiber slack.

Which type of network topology allows troubleshooting a problem or switching around the problem to be accomplished easily from the central hub?

Star.

What is used in outside plant fiber-optic cable to protect and isolate the optical fibers from stress?

Strength members and buffer tubes.

Since they can provide the same functions, what is the primary difference between the fiber distribution hub (FDH) and the fiber access terminal (FAT)?

The FAT is typically easier to install and has lower fiber counts than the FDH.

What type of single-mode fiber is intended for fiber-to-the-home (FTTH) installations?

The ITU-T G.657 bend-insensitive fiber (BIF).

Which standards organization is considered to be the creator of the world's most recognized communications standards, known as "recommendations?"

The International Telecommunication Union (ITU).

Why are light emitting diodes (LED) most effective when coupled to multimode fiber?

The LED emits optical energy in hundreds of pathways, each carrying the same data that is coupled into a fiber in separate paths or modes.

What are the two accepted methods for pulling fiber-optic cable off the cable reel as part of an aerial installation?

The back-pull method and the drive-off method.

What is one process that has to happen before digital modulation can occur in an optical transmitter?

The data must be encoded.

The phenomenon, total internal reflection, is what enables an optical fiber to guide light. What characteristic of optical fiber causes total internal reflection?

The difference in refractive indexes, between cladding and core, causes light to be reflected off the cladding and back into the core along the optical fiber.

If tight-buffered distribution fiber-optic cable is installed between the master splice panel in an optical entrance enclosure (OEE) and a rack-mounted fiber-optic distribution panel, where in the facility must the distribution panel be located?

The distribution panel can be located anywhere in the facility since the distribution cable complies with indoor code requirements for riser or plenum installations.

What is a drawback of using Fabry-Perot (F-P) lasers in high-speed data (HSD) networks?

The emission of a number of discrete wavelengths or side modes.

Which type of fusion splicer is ideal for fiber-to-the-x (FTTx) splicing?

The fixed V-groove splicer.

What is one advantage and one disadvantage of single-mode fiber with a large mode field diameter (MFD)?

The larger the MFD, the easier it is to splice and connectorize the fiber, although it becomes more sensitive to bending losses.

What is a characteristic of light in a laser beam?

The laser beam consists of a limited range of wavelengths (monochromatic), with all light waves in phase (coherent light).

In underground installations, what are two recommended techniques that prevent the pulling tension through the conduit from exceeding the pulling tension specification of the fiber-optic cable?

The midpoint pull and the intermediate pull.

What is true of the following types of uninterruptible power supplies (UPS)?

The offline type routes incoming power directly to connected devices and switches to battery backup during a power interruption.

What occurs in the wavelength division multiplexing (WDM) process?

The optical output from multiple lasers operating at different wavelengths is combined and transported over a single, common optical fiber.

In which component in a fiber-optics communications system do changes to the intensity of the optical signal occur?

The optical transmitter.

Which fusion splicer alignment method uses a camera to align the optical fibers before splicing?

The profile alignment system (PAS) method.

The quality and attenuation value of a mechanical splice of optical fibers is dependent on which tool during the preparation process?

The quality and attenuation value of the mechanical splice of optical fibers is dependent on the quality of the cleaving tool.

When working on a ladder, which rungs are forbidden for standing?

The top two rungs of any ladder.

When installing aerial fiber-optic cable employing the back-pull method, how should the cable trailer be positioned in order to keep the cable from rubbing on the pole or cable reel when pulled?

The trailer should be positioned in line with the strand and at least twice the distance from the pole as the height from the ground to the set-up chute

The frame structure of a synchronous transport signal (STS) is divided into two parts. What are they?

The transport overhead, which contains the section and line layers, and the synchronous payload envelope, which contains the path overhead and the payload data.

How is the high air speed blowing (HASB) method of installing fiber-optic cable in conduit different from other methods?

There is no need for a pulling rope in the conduit before the cable is installed.

What is true of online uninterruptible power supply (UPS) systems?

They are recommended for commercial applications such as data centers and telecommunications operations.

Which of the following is true about optical nodes?

They contain four main sections: the optical receiver, the RF amplifier module, the reverse optical transmitter, and the DC power supply.

How do technicians know the specific type of single-mode fiber used in a particular project?

They have read the project's specification records.

How does an optical node receive AC voltage?

Through a power cable that is connected from the power supply directly to the power port of the node.

When preparing a fiber-optic cable for splicing, what is the purpose of removing approximately 2.5 cm (1 inch) of the jacket and any armor that is present from the end of the cable?

To access the cable's rip cord and to check the cutting depth of the knife or ringing tool.

What is the core objective of the Data Over Cable Service Interface Specification (DOCSIS) Provisioning of Ethernet passive optical network (EPON), or DPoE, access architecture?

To make the EPON elements appear and operate as DOCSIS elements to the existing DOCSIS-based back office provisioning operations.

When splicing fiber-optic cable, why is it a good safety practice to clean off fiber strippers and other hand tools after each use?

To prevent the accidental transfer of fiber debris or fiber chips onto clean hands.

Why was the zero-dispersion point in single-mode fiber moved to 1,550 nm?

To take advantage of the low intrinsic absorption and lower attenuation at 1,550 nm in single-mode fiber.

When preparing a splice closure, what should be done with the fiberglass rod strength member that runs down the center of loose-tube fiber-optic cable?

Trim the strength member back for convenience, but leave it long enough to be tightly clamped to a strain-relief lug in the closure.

In a passive optical network (PON), which category of fiber-optic cable is routed from the headend into the optical distribution network (ODN)?

Trunk.

Typically, what is the first step to take when adjusting an optical receiver?

Turn on the optical receiver.

Digital return path transmissions

Use dense wavelength division multiplexing (DWDM) digital return transmitters in hub-to-headend architectures.

What is the ideal way for a broadband cable network designer to plan the replacement of coaxial cable with fiber-optic cable to shorten amplifier cascades?

Use the existing coaxial network infrastructure.

What does water do to the glass core of an optical fiber?

Water causes the glass core of the optical fiber to become opaque, which degrades the signal as it's transported through the fiber.

Which of the following statements about AC power distribution at the optical node is not true?

When primary and secondary network power supplies are used at the node, a jumper directs only primary AC power to both of the DC backup power supplies.

When is it necessary to use the intermediate pull technique to install fiber-optic cable in conduit?

When the cable route has multiple 90° bends throughout.

Which of the following statements about local ad insertion is true?

Local ad insertion is performed usually by a video server.

Which type of fiber-optic cable provides the most stable transport characteristics and additional protection from stresses caused by macrobends and microbends?

Loose-tube cable.

Some advantages of using flexible conduit are:

Low coefficient of friction (COF) and the capability to bend around corners and obstructions with minimal splices.

What step should be performed at the beginning of every fusion splicing operation?

Make a number of test splices to set up the fusion splicer and to verify the instrument's settings and calibration for both the environment and the type of fiber to be spliced.

What are the primary causes of intrinsic loss in single-mode fiber?

Material absorption and Rayleigh scattering.

Chromatic dispersion is a combination of which two dispersions?

Material and waveguide dispersion.

The National Electrical Safety Code (NESC) provides guidelines concerning which portion of the fiber-optic cable network?

Minimum safety clearances between different conductors of overhead and underground electric supply and communications lines.

Eliminating pulling lines using high air speed blowing (HASB) can achieve how much of a cost savings over conventional pulling techniques?

More than 40%.

In anticipation of next-generation access (NGA) architectures, the gigabit-capable passive optical network (GPON) wavelength allocation provided optional bands for upstream wavelengths. Which of these optional bands is for distributed feedback (DFB) lasers?

Narrow wavelength band.

Which of these items should be identified on a route map?

Parks.

Which layer of a synchronous optical network (SONET) maps the signals into a synchronous payload envelope (SPE)?

Path.

How should the buffer tubes be secured in the closure?

The buffer tubes should be secured with tie wraps to allow slight movement without pulling or stressing the optical fibers.

What is a concern when aerial fiber-optic cable is installed between poles, even though there are no high-voltage power lines?

The buildup of lethal amounts of static electricity on the fiber-optic cable that can discharge through a person on a ladder or some other conductor connected to ground.

In regard to providing high-speed data (HSD) service,

The cable modem termination system (CMTS) can provide a data transfer rate up to 38 Mbps, using 256-QAM.

What is required of mechanical splices used for acceptance testing?

A mechanical splice used for acceptance testing should be simple to use and reusable.

Why are the amplitude levels into an optical transmitter different between analog television and quadrature amplitude modulation (QAM) carriers?

Because analog carriers have a video sync pulse, which can be used to set amplitude. QAM carriers don't have a sync pulse; so the average power of the carrier is used to adjust the QAM carrier's amplitude.

When would a mid-entry splice in a fiber-optic network be used?

In a self-healing ring network that requires only two fibers to feed an optical fiber drop.

How are optical splitters used in the forward path?

In the forward path, optical splitters are used as passive branching devices that divide an optical signal across multiple output fibers.

In normal power operation,

Incoming commercial power is directed to battery charging circuitry that maintains a proper charge on the backup batteries.

A technician is determining whether the optical power into an optical receiver is within the acceptable dynamic range. He finds that the optical power is too high, but the loss budget agrees with the design. What should he do to optimize the optical power in this situation?

Install an optical attenuator.

What should be done to prevent the buildup of lethal amounts of static electricity on long lengths of aerial fiber-optic cable?

Install grounding clamps, which connect the cable exterior and metallic messengers to a good solid ground at each pole site.

Select the answer that best completes this sentence: In analog modulation, the _____ of the light wave changes in _____ proportion to the _____ analog signal.

Intensity; direct; incoming

Monitoring the status of optical nodes

Involves the use of a node transponder that continuously monitors a number of critical functions.