SPECTRUM DESIGNER 1 -> 2

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

2.5 Gbps

The process of combing digital services in the headend is called:

Multiplexing

What is the expected DC voltage on most hybrid fiber coax (HFC) network equipment?

+24 VDC, +_ 0.5V

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.

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 value of interstage equalizer should be installed if the associated amplifier tombstone field is blank and the amplifier output slope is 7 dB?

7 dB.

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?

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How is the AC voltage separated from the RF signal in a distribution amplifier?

???By a capacitor that passes RF but blocks the low frequency 60 hertz (Hz) AC voltage which finds a low resistance path through the RF choke that blocks RF.????

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.

Shorts in the coaxial cable and excessive amounts of current can damage the distribution amplifier. Several devices can be used to protect the distribution amplifier from these problems. Which device shorts to ground when an overvoltage situation occurs?

A fast transfer electronic crowbar (FTEC).

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 can be used as a pulling line in a conduit that is missing a pull line?

A polyethylene terephthalate rope that can be installed by vacuum.

What is Moving Picture Experts GroupMPEG?

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

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

A well-lit location that is large enough for a table to accommodate the fusion splicer, tools, and the splice closure.

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.

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 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.

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 carrier is used to adjust the QAM carrier's amplitude

What is required for checking the physical network integrity when maintaining the coaxial cable network?

Being observant and performing some minor tasks while engaged in regularly scheduled activities

What is the purpose for distribution amplifiers in a hybrid fiber/coax (HFC) network?

Boost the downstream signals before being divided and circulated throughout neighborhoods in the coaxial cable portion of the network.

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 require too many new drops to be created.

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

Coaxial cable.

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.

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

Coarse wavelength division multiplexingCWDM applications were expanded to include use in what band, where a large OH absorption loss occurred with older single-mode fibers?

E-band.

Where does a distribution amplifier module receive the direct current (DC) required for operation?

From a DC power supply module that converts the alternating current (AC) voltage to DC voltage.

What technologies are defined in DOCSIS 4.0 to help sustain the Hybrid fiber/coaxHFC network infrastructure for several more years?

Full Duplex DOCSISFDX and Extended Spectrum DOCSISESD.

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 taperFBT.

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.

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 dro

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 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.

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 multiplexingWWDM used?

It is used in passive optical networks.

What does a thermal control circuit in a distribution amplifier do?

It maintains the amplifier output levels as the input levels vary with temperature changes.

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

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.

What are some advantages of using flexible conduit?

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.

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 requirements to be followed when entering, exiting, and working in confined spaces.

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

More than 40%.

What term describes the frequency spectrum into an amplifier having higher amplitude at low frequencies than the high frequencies?

Negative tilt.

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 photodiodeAPD introduce into the electrical output of an optical detector?

Noise.

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

Optical receiver.

What product based on the Data Over Cable Service Interface SpecificationDOCSIS defines the protocols for Internet protocolIP telephony over Hybrid fiber/coaxHFC networks?

PacketCable.

Which layer of a Synchronous optical networkSONET maps the signals into a Synchronous payload envelopeSPE?

Path.

What is used to select which distribution amplifier secondary downstream output ports are active and whether they have equal or unequal output levels?

Plug-in modules or jumpers.

In a centralized server Video-on-demandVOD architecture,

QAM modulators located in the customer premises convert video content to RF for delivery over the HFC network to the regional headend.

In an optical network, what is reflectance?

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

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 areas?

Ring.

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.

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.

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

TRUNK

Since they provide the same functions, what is the primary difference between the Fiber distribution hubFDH and Fiber access terminalFAT?

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

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

The International Telecommunication UnionITU.

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.

How can a distribution amplifier be identified in the network or on a network design map?

The distribution amplifier has multiple downstream outputs

When configuring the upstream return in a distribution amplifier with multiple upstream ports, the amplitude levels for which port should be adjusted first?

The distribution amplifier upstream port with the most attenuation in its upstream path.

What is a drawback of using Fabry-Perot (F-P) lasers in high-speed dataHSD 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.

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

The fixed V-groove splicer.

When opening a distribution amplifier station housing, why is it usually unnecessary to loosen the bolts at the bottom of the housing?

The housing lid is usually attached to the base of the housing with hinges.

When configuring the input stage of a distribution amplifier, what element values can vary from those in the amplifier tombstone, depending on the input amplitude measurements?

The input equalizer and attenuator pad values.????

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)

Why are laser diodes most effective when coupled to singlemode fiber?

The laser's wavelength is 75 degrees from the transmitted wavelength.

How can a less-experienced technician identify what non-standard symbols on the network design maps represent?

The legend at the bottom of the network design map that defines the map symbols, cable types, and amplifier data.

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.

Why is the term "gain control" applied to amplifier gain and controls inaccurate?

The only way to vary the output of any amplifier is to adjust the amplitude level of the signal going into the amplifier.

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 signalSTS 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 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 a distribution amplifier in a fiber node receive the downstream radio frequency (RF) signals?

Through a coaxial cable that is connected to the downstream optical receiver.

What test instrument sends out a test signal and displays any reflections caused by impedance mismatches in the cable that are characteristic of cable faults?

Time domain reflectometerTDR

Describe an application for a distribution amplifier in a hybrid fiber/coax (HFC) network?

To maintain downstream amplitude levels to the addresses farthest from the fiber-node.

What is the purpose of grounding to earth?

To protect against the adverse effects of lightning

In a distribution amplifier, why is the frequency response at the input of the second output stage sloped?

To reduce intermodulation distortion levels caused by amplifying high amplitude input levels.

Why is there a diplex filter at each downstream output port in a distribution amplifier?

To separate the downstream radio frequency (RF) from the upstream RF signals.

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.

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

Turn on the optical receiver.

What is the basic amplifier application that increases the amplitude of the radio frequency (RF) signal to compensate for the signal loss of cable and passive devices preceding the amplifier called?

Unity gain.

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 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 home (FTTH)

Which type of Passive Optical Network (PON) topology places the optical splitters at the headend, and then routes them to each individual customer premises?

home run