Fiber Installation and Activation
In networks transporting data rates that are higher than _____, Fabry-Perot (F-P) lasers are considered inadequate.
2.5 Gbps
What is the difference FTTN and FTTC topologies?
An FTTC is allowed a smaller number of RF amplifiers between the optical fiber and customer premises.
Eliminating pull lines using HASB can achieve how much of a cost savings over conventional pulling techniques?
More than 40%
In regard to providing high-speed data (HSD) service,
The CMTS can provide a data transfer rate up to 38Mbps using 256-QAM in a single 6MHz channel.
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.
What is the purpose of grounding to earth?
(1) To protect against the adverse effects of lightening; (2) assist in the reduction of static; and (3) bring a zero-voltage reference to system components.
The 10GEPON 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 architecture?
10Gbps 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 inbound and outbound span.
How many meters of slack cable are typically used in aerial installation?
15-25 meters.
What is the maximum data rate the 10GPON access architecture supports in the upstream?
2.5 Gbps
What is the minimum clearance in the middle of a cable span between the powers secondary conductor and the fiber-optic cable belonging to a broadband cable operator?
30"
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 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 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 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 required of mechanical splices used for acceptance testing?
A mechanical splice used for acceptance testing should be simple to use and reusable.
What is MPEG?
A universally accepted standard for digital television, first released in 1992.
What is a 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 that is missing a pull line?
An unused cable that is already installed in the conduit.
Where would you expect Fresnel reflections to occur in a fiber-optic network?
At connections and mechanical splices where the signal source is entering or exiting the cable.
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, the average power of the video carrier is used to adjust the QAM carrier's amplitude.
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 hold the pigtails together without placing undue strain on the optical fibers.
What is the wavelength allocation for video distribution (RF overlay) in BPON access systems?
Between 1550 and 1560 nm
What is the purpose of buffer tubes in fiber-optic cable?
Buffer tubes protect and separate the optical fibers 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 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.
The quality and attenuation value of a mechanical splice of optical fibers is dependent on which tool during the preparation process?
Cleaving tool
What is an example of transport media in a telecommunications network?
Coaxial cable.
In a HFC fiber optic node, what are common voltages produced by DC power supplies?
Common voltages produced by DC power supplies include 5, 12, and 14 VDC
Which of these are concerns for RFoG and FTTx systems?
Consideration of how and who will provide AC power to the ONT at the customer premises.
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.
What 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 the intensity changes in the light wave?
Direct
Which type of star topology used in a PON places the PON splitters into the FAT located deep in the network and closer to the customer premises than the centralized split?
Distributed star
When activating a fiber-optic network, which acceptance testing stage includes adjusting attenuation levels for the first time?
During equipment activation
CWDM applications were expanded to include use in what band, where a large absorption loss occurred with older single mode fibers?
E-band.
Which type of optical amplifier produces no measurable distortion to the modulated light wave?
EDFA.
Which type of PON architecture was formed to develop a cost-effective, high bandwidth,easy-to-provision solutionmfor connecting businesses, schools, libraries, and customer local area networks to the public internet?
EPON
Which optical splitter package is similar in appearance and size to a standard fusion splice protector?
FBT
What type of FTTx topology does a PON use to make a P2MP fiber-optic cable connection between the broadband cable headend and the customer premises?
FTTH
What information should always be included in fiber-optic network documentation?
Fiber assignments
Why do many optical nodes accept two independent power supplies?
For redundant powering of the node.
Besides protection, what else must the coating on an optical fiber cable 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 type of optical coupler provides the least amount of insertion loss?
Fused.
Which type of PON access architecture replaced APON?
GPON
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.
What is one element used in the transmission and reception of DWDM?
High quality, temperature cooled distributed feedback lasers.
Which standards organization is considered to be the creator of the world's most recognized communications standards, know as "recommendations"?
ITU
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.
What information is documented at fiber-optic slack and slice locations?
Incoming and outgoing sequential markings showing the cable's physical length.
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 static electricity on long lengths of 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.
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 centralized power node?
It can provide sufficient power for a fiber-optic node, including outside plant amplifiers and customer premises NIDs for telephony service.
What is the current standardized outside diameter of the cladding of SMF?
It is 125um, with an accuracy of +-1um
What is digital modulation?
It is the interruption of light waves in a coded sequence.
In what type of installation is WWDM used?
It is used in passive optical networks.
Why might a technician who is troubleshooting an outage in an optical network what to refer to the network's as-built documentation?
It will help the technician determine specific cable lengths.
What 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.
Why are laser diodes most effective when coupled to a singlemode fiber?
It's high coupled power, directionality. and speed.
What is a design option for a broadband cable network to maximize the use of its optical fiber resources?
Leasing spare fibers.
When preparing the 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.
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 macro and microbends?
Loose-tube cable
What are some advantages of using flexible conduit?
Low COF and the capability to bend around 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 instruments settings and calibration for both the environment and the type of fiber to be spliced.
What are the primary causes of intrinsic loss in SMF?
Material absorption and Rayleigh scattering
Chromatic dispersion is a combination of which two dispersions?
Material and waveguide dispersion.
The 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.
What does the amplification process in an APD introduce into the electrical output of an optical detector?
Noise
What are the factors that contribute to an optical receiver's sensitivity?
Noise, responsitivity, response time, linear response, back reflection, and optical detector material.
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 PON consists of a downstream optical transmitter, an upstream receiver, and a multiplexer/demultiplexer?
OLT
Which component of an optical modulation system contains an optical detector and demodulator?
Optical reciever
Which component of a digital optical network is used to receive digital modulation light waves and covert them to an electrical signal?
Optical transponder.
What is a benefit of using P2P topology instead of a P2MP topology?
P2P topologies are more stable than P2MP topologies.
What product based on the DOCSIS defines the protocols for IP telephony over HFC networks?
PacketCable
Which of these items should be identified on a route map?
Parks
Ehich layer of a SONET maps the signals into an SPE?
Path
What statement about pigtails used for optical fiber termination is true?
Prior to splicing, pigtails should be labelled to correspond with the correct color code and patch panel designation.
What is it about RFoG that made broadband cable operators envision using it to make a seamless transition from the legacy HFC architecture over to a GPON or EPON?
RFoG can operate in parallel with GPON or EPON operating independent of the PON communications protocols and data rates.
In an optical network, what is reflectance?
Reflectance is the reflected light from a single Fresnel reflection event.
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 different tools and equipment to perform splicing.
Which type of network topology has been focused primarily on alternative routing around cities and industrial area?
Ring
Which of the following is true about the SONET transmission standard?
SONET is the North American standard used for telephony applications.
When installing fiber-optic cable of 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.
What category of fiber-optic cable design typically uses some variation of the star topology?
Signal distribution
In what application 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 blow 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, 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 provide the same functions, what is the primary difference between the FDH and the 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 FTTH installations?
The ITU-T G.657 BiF
Which fusion splicer alignment method uses a camera to align the optical fibers before splicing?
The PAS method.
What are two accepted methods for pulling fiber-optic cable off the cable reel as part of an aerial installation?
The back-pull method and drive-off method.
How should 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 the ground.
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 the drawback of using F-P lasers in HSD networks?
The emission of a number of discrete wavelengths or side modes.
What are the two critical elements that align the optical fibers in a connection?
The ferrules and the mating adapter.
What type of fusion splicer is ideal for FTTx splicing?
The fixed V-groove splicer.
What is one advantage and one disadvantage of SMF with a large 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 intermediate pull.
In a centralized server VOD architecture,
The number of servers needed for video content storage is smaller than in distributed server architecture.
What is true of the following types of UPS?
The offline routes incoming power directly to connected devices and switches to battery backup during a power interruption.
What occurs in the WDM process?
The optical output from multiple lasers operating at different wavelengths is combined and transported over a common optical fiber.
In which component in a fiber-optics communication system do changes to the intensity of the optical signal occur?
The optical transmitter
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 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 an 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 payload data.
How is the 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 data centers and telecommunications operations.
Which of the following is true about optical nodes?
They contain four main sections: the optical reciever, 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.
Why is -48VDC with a positive ground used by the telecommunication industry?
This reverse polarity is a means of mitigating electrolyte corrosion on the outside plant.
What is an option available on most optical nodes for connecting to the power supply?
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 1 inch of jacket and any armor that is present, from the end of the cable?
To access the cables 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 are backup AC generators included in many commercial AC UPS and DC power systems?
To provide AC power in the event of a prolonged utility power interruption.
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 1550nm 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 PON, which category of fiber optic cable is routed from the headend into the 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 cables to shorten amplifier cascades?
Use the existing coaxial cable network infrastructure.
What does water do to the glass core of an optical fiber?
Water causes the glass fiber to become opaque, which degrades the signal as its transported through the fiber.