Download FIBER INSTALLATION AND ACTIVATION and more Exams Telecommunications Engineering in PDF only on Docsity!
FIBER INSTALLATION AND
ACTIVATION EXAM
What information should always be included in fiber-optic network documentation? - ANSWERS-Fiber assignments Why might a technician who is troubleshooting an outage in an optical network what to refer to the network's as-built documentation?
- ANSWERS-It will help the technician determine specific cable lengths. The number of rectifiers used in a DC power plant design - ANSWERS-Is dependent upon the load placed on the system. What is true of online uninterruptible power supply (UPS) systems? - ANSWERS-They are recommended for commercial applications such as data centers data centers and telecommunications operations. Which of these are concerns for RFoG and FTTx systems? - ANSWERS-Consideration of how and who will provide AC power to the ONT at the customer premises. What is true of the following types of UPS? - ANSWERS-The offline routes incoming power directly to connected devices and switches to battery backup during a power interruption.
Why are backup AC generators included in many commercial AC UPS and DC power systems? - ANSWERS-To provide AC power in the event of a prolonged utility power interruption. Why is - 48VDC with a positive ground used by the telecommunication industry? - ANSWERS-This reverse polarity is a means of mitigating electrolyte corrosion on the outside plant. Which of the following is true of a centralized power node? - ANSWERS-It can provide sufficient power for a fiber-optic node, including outside plant amplifiers and customer premises NIDs for telephony service. What is an option available on most optical nodes for connecting to the power supply? - ANSWERS-Through a power cable that is connected from the power supply directly to the power port of the node. Why do many optical nodes accept two independent power supplies?
- ANSWERS-For redundant powering of the node. In a HFC fiber optic node, what are common voltages produced by DC power supplies? - ANSWERS-Common voltages produced by DC power supplies include 5, 12, and 14 VDC Which type of PON access architecture replaced APON? - ANSWERS-GPON
What is the maximum data rate the 10GPON access architecture supports in the upstream? - ANSWERS-2.5 Gbps The 10GEPON access architecture supports two data rates in the upstream. What are they? - ANSWERS-1 Gbps and 10 Gbps What is a benefit of using P2P topology instead of a P2MP topology?
- ANSWERS-P2P topologies are more stable than P2MP topologies. Which standards organization is considered to be the creator of the world's most recognized communications standards, know as "recommendations"? - ANSWERS-ITU In which component in a fiber-optics communication system do changes to the intensity of the optical signal occur? - ANSWERS-The optical transmitter What is the drawback of using F-P lasers in HSD networks? - ANSWERS-The emission of a number of discrete wavelengths or side modes. Why are laser diodes most effective when coupled to a singlemode fiber? - ANSWERS-It's high coupled power, directionality. and speed. What are the factors that contribute to an optical receiver's sensitivity?
- ANSWERS-Noise, responsitivity, response time, linear response, back reflection, and optical detector material.
What is a PIN diode? - ANSWERS-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 does the amplification process in an APD introduce into the electrical output of an optical detector? - ANSWERS-Noise What functions does the detector in an optical receiver perform? - ANSWERS-Conversion of an optical carrier to an electrical signal, and demodulation of the modulated optical carrier. What happens if the optical signal exceeds the maximum specified input power into a photodetector? - ANSWERS-Nonlinear operation resulting in distortion, data errors, and signal loss. What is a characteristic of light in a laser beam? - ANSWERS-The laser beam consists of a limited range of wavelengths (monochromatic), with all light waves in phase (coherent light). Monitoring the status of optical nodes - ANSWERS-Involves the use of a node transponder that continuously monitors a number of critical functions. Digital return path transmissions - ANSWERS-Use dense wavelength division multiplexing (DWDM) digital return transmitters in hub-to- headend architectures.
Which of the following is true about the SONET transmission standard? - ANSWERS-SONET is the North American standard used for telephony applications. Why was the zero-dispersion point in single-mode fiber moved to 1,550 nm? - ANSWERS-To take advantage of the low intrinsic absorption and lower attenuation at 1550nm single-mode fiber. What type of single-mode fiber is intended for FTTH installations? - ANSWERS-The ITU-T G.657 BiF What are the primary causes of intrinsic loss in SMF? - ANSWERS- Material absorption and Rayleigh scattering The phenomenon, total internal reflection, is what enables an optical fiber to guide light. What characteristic of optical fiber causes total internal reflection? - ANSWERS-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. Where would you expect Fresnel reflections to occur in a fiber-optic network? - ANSWERS-At connections and mechanical splices where the signal source is entering or exiting the cable. Chromatic dispersion is a combination of which two dispersions? - ANSWERS-Material and waveguide dispersion.
What is one advantage and one disadvantage of SMF with a large MFD? - ANSWERS-The larger the MFD, the easier it is to splice and connectorize the fiber, although it becomes more sensitive to bending losses. What is the current standardized outside diameter of the cladding of SMF? - ANSWERS-It is 125um, with an accuracy of +-1um What do diameter differences between spliced fibers look like on an optical time domain reflectometer (OTDR)? - ANSWERS-Gain in one direction and high loss in the opposite direction. Besides protection, what else must the coating on an optical fiber cable do? - ANSWERS-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. How do technicians know the specific type of single-mode fiber used in a particular project? - ANSWERS-They have read the project's specification records. Which type of fiber-optic cable provides the most stable transport characteristics and additional protection from stresses caused by macro and microbends? - ANSWERS-Loose-tube cable
Which optical splitter package is similar in appearance and size to a standard fusion splice protector? - ANSWERS-FBT In what application is a splice closure used? - ANSWERS-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. 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? - ANSWERS-To access the cables rip cord and to check the cutting depth of the knife or ringing tool. What does water do to the glass core of an optical fiber? - ANSWERS-Water causes the glass fiber to become opaque, which degrades the signal as its transported through the 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? - ANSWERS-Trim the strength member back for convenience, but leave it long enough to be tightly clamped to a strain-relief lug in the closure. What is the purpose of splice trays inside splice closures? - ANSWERS-Splice trays are designed to provide protection for mechanical splices, fusion splice protectors, as well as provide storage for the required fiber slack.
How should buffer tubes be secured in the closure? - ANSWERS-The buffer tubes should be secured with tie wraps to allow slight movement without pulling or stressing the optical fibers. How are optical splices secured in a splice tray? - ANSWERS- Retaining clips hold optical splices in place in a splice tray. What is the purpose of buffer tubes in fiber-optic cable? - ANSWERS-Buffer tubes protect and separate the optical fibers in smaller bundles. When splicing fiber-optic cable, why is it a good safety practice to clean off fiber strippers and other hand tools after each use? - ANSWERS-To prevent the accidental transfer of fiber debris or fiber chips onto clean hands. Where would you expect to install a mid-entry splice in a fiber-optic cable network? - ANSWERS-A location where a select number of optical fibers need to be spliced, and the remaining buffer tubes and fibers remain untouched. When would a mid-entry splice in a fiber-optic network be used? - ANSWERS-In a self healing ring network that requires only two fibers to feed an optical fiber drop. What are some prerequisites before performing a fusion splice of optical fibers? - ANSWERS-A controlled environment such as a
be located anywhere in the facility since the distribution cable complies with indoor code requirements for riser or plenum installations. The quality and attenuation value of a mechanical splice of optical fibers is dependent on which tool during the preparation process? - ANSWERS-Cleaving tool What step should be performed at the beginning of every fusion splicing operation? - ANSWERS-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. Which fusion splicer alignment method uses a camera to align the optical fibers before splicing? - ANSWERS-The PAS method. The NESC provides guidelines concerning which portion of the fiber optic cable network? - ANSWERS-Minimum safety clearances between different conductors of overhead and underground electric supply and communications lines. What is a concern when aerial fiber-optic cable is installed between poles, even though there are no high voltage power lines? - ANSWERS-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 used in outside plant fiber-optic cable to protect and isolate the optical fibers from stress? - ANSWERS-Strength members and buffer tubes. What is the purpose of grounding to earth? - ANSWERS-(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. What is the minimum amount of slack that must be provided for splicing fiber-optic cable in underground installations? - ANSWERS- 15 meters on inbound and outbound span. What information is documented at fiber-optic slack and slice locations? - ANSWERS-Incoming and outgoing sequential markings showing the cable's physical length. What can be attached to the pulling line to prevent the fiber-optic cable from twisting during installation? - ANSWERS-A break-away swivel. What should be done to prevent the buildup of lethal static electricity on long lengths of fiber-optic cable? - ANSWERS-Install grounding clamps, which connect the cable exterior and metallic messengers to a good solid ground at each pole site. When working on a ladder, which rungs are forbidden for standing? - ANSWERS-The top two rungs of any ladder.
Eliminating pull lines using HASB can achieve how much of a cost savings over conventional pulling techniques? - ANSWERS-More than 40% When is it necessary to use the intermediate pull technique to install fiber-optic cable in conduit? - ANSWERS-When the cable route has multiple 90* bends throughout. When installing fiber-optic cable of coaxial cable, what should be done at the coaxial cable expansion loops? - ANSWERS-Secure the fiber optic cable to the strand across the coaxial cable expansion loops using plastic cable ties or support straps. What are two accepted methods for pulling fiber-optic cable off the cable reel as part of an aerial installation? - ANSWERS-The back-pull method and drive-off method. Which component of an optical modulation system contains an optical detector and demodulator? - ANSWERS-Optical reciever What is digital modulation? - ANSWERS-It is the interruption of light waves in a coded sequence. Select the answer that best completes this sentence: In analog modulation, the of the light wave changes in proportion to the analog signal. - ANSWERS-Intensity, direct, incoming.
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? - ANSWERS-Direct Ehich layer of a SONET maps the signals into an SPE? - ANSWERS- Path The frame structure of an STS is divided into two parts. What are they? - ANSWERS-The transport overhead, which contains the section and line layers, and the synchronous payload envelope, which contains the path overhead and payload data. What occurs in the WDM process? - ANSWERS-The optical output from multiple lasers operating at different wavelengths is combined and transported over a common optical fiber. In what type of installation is WWDM used? - ANSWERS-It is used in passive optical networks. CWDM applications were expanded to include use in what band, where a large absorption loss occurred with older single mode fibers?
- ANSWERS-E-band. What is one element used in the transmission and reception of DWDM? - ANSWERS-High quality, temperature cooled distributed feedback lasers.
What is the difference FTTN and FTTC topologies? - ANSWERS-An FTTC is allowed a smaller number of RF amplifiers between the optical fiber and customer premises. 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? - ANSWERS-FTTH In a PON, which category of fiber optic cable is routed from the headend into the ODN? - ANSWERS-Trunk 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? - ANSWERS-Distributed star What are the main elements of an optical transmitter? - ANSWERS- Data encoder/modulator, electrical interface, laser, optical interface What is one process that has to happen before digital modulation can occur in an optical transmitter? - ANSWERS-The data must be encoded. In networks transporting data rates that are higher than , Fabry- Perot (F-P) lasers are considered inadequate. - ANSWERS-2.5 Gbps Why are the amplitude levels into an optical transmitter different between analog television and quadrature amplitude modulation
(QAM) carriers? - ANSWERS-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. What are the main elements of an optical receiver? - ANSWERS- Demodulator, electrical interface, optical detector, optical interface. 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? - ANSWERS-Install an optical attenuator. Typically, what is the first step to take when adjusting an optical receiver? - ANSWERS-Turn on the optical receiver. Which type of optical amplifier produces no measurable distortion to the modulated light wave? - ANSWERS-EDFA. Which component of a digital optical network is used to receive digital modulation light waves and covert them to an electrical signal?
- ANSWERS-Optical transponder. Which type of optical coupler provides the least amount of insertion loss? - ANSWERS-Fused.
