NCTI MT1-MT2 FINAL EXAM CURRENTLY TESTING VERSIONS OF THE EXAM WITH QUESTIONS AND CORRECT DETAILED ANSWERS/EXPERT VERIFIED FOR GUARANTEED PASS! /LATEST UPDATE

NCTI MT1-MT2 FINAL EXAM CURRENTLY TESTING VERSIONS OF THE EXAM WITH QUESTIONS AND CORRECT DETAILED ANSWERS/EXPERT VERIFIED FOR GUARANTEED PASS! /LATEST UPDATE According to SCTE- and NCTA- recommended trunk system map symbols, fiber-optic cable is represented by - Correct Answer Double arrows within a small circle on a solid line." "The forward path signal in a traditional tree-and-branch architecture - Correct Answer originates at the headend and is transmitted downstream through coaxial trunk cable and trunk amplifier." "Across 6 MHz, what is the maximum in- channel frequency response (ICFR) defined in the Data Over Cable Service Interface Specification (DOCSIS)? - Correct Answer 3.0 dB peak-to-valley (P/N)." "When sweeping the upstream return path in a hybrid fiber coax (HFC) network, where are the upstream levels and sweep responses measured? - Correct Answer The Headend." "Even though the downstream sweep test pulses are intended to fit in the narrow frequency band between channels, what parameter can cause interference if set too high? - Correct Answer Sweep test pulse amplitude." "What does a normalized reference trace from a fiber-node test point eliminate from the sweep process? - Correct Answer Slope response variations of the Headend and optical transport." "In a HFC network, - Correct Answer Processing equipment in the headend converts the forward RF signal to a light signal." "During aerial plant construction, - Correct Answer The strand is tensioned so its sag profile matches that of the overhead utility power lines." "With underground plant construction, - Correct Answer The fiber-optic and coaxial cables are often places underground with other utility lines to jointly share construction costs." "Standby power supplies - Correct Answer continue providing an output voltage even during a utility power outage by using a back up power source." "Centralized power configurations - Correct Answer provide the advantage of increased reliability through sharing of expensive backup generators and sophisticated monitoring equipment among different power realms." "When transmitting broadband signals - Correct Answer In a two way hybrid fiber/coax (HFC) network, two or more individual optical fibers are required for each optical node location." "RF trunk amplifiers - Correct Answer Have attenuator pads, equalizers, and duplex filters that control and route the RF signals." "Verifying plant reliability includes - Correct Answer Frequency response sweeping, which is adjusting RF amplifier circuits to amplify all frequencies in the bandpass spectrum as equally as possible" "Which of the following is a requirement in the process for measuring leakage using a dipole antenna, as required by the FCC? - Correct Answer The antenna must be placed 3 meters from the system components and 3 meters from the ground." "Many cable companies require which type of leaks to be fixed? - Correct Answer All types of leaks must be fixed." "According to the FCC, the leakage log should contain which of the following? - Correct Answer The probable cause of the leakage." "Which of the following FCC required information must a cable system keep on file for two years? - Correct Answer Annual CLI calculations, regular (quarterly) monitoring programs, and a list of all channels used in the aeronautical bands." "If your leakage detector indicates there is a leak and displays a reading of 14 microvolts per meter (uV/m) when you are 80 feet from a possible leak source, what is the approximate calculated level of the leak from 10 feet? - Correct Answer 112 uV/m." "If a large signal leak is found in the aerial plant, what is a good first step in locating the leak? - Correct Answer Drive around until an absolute peak is found." "Which of the following best describes demand maintenance procedures with regard to signal leakage? - Correct Answer The demand maintenance procedures can improve the CLI measurement results by identifying and correcting the largest leaks first." "When troubleshooting signal leakage in the drop system, what is indicated if all signs of signal leakage disappear when the ground block is disconnected and terminated on the side connected to the customer premises? - Correct Answer The backward route from the ground block to the tap can be eliminated as a source of The backward route from the ground block to the tap can be eliminated as source of leakage." "Which typical over-the-air signal sources can cause a false alarm with a signal leakage detector? - Correct Answer Typical sources include aircraft communication signals and ham, mobile, and government radio broadcasts." "When adjusting or selecting the elements of a dipole antenna for measuring signal leakage, what is the approximate length of each element relative to the wavelength of the signal being measured? - Correct Answer One-quarter wavelength." "Which of the following problem(s) are caused by egress? - Correct Answer Interference with aeronautieal navigation and communication, amateur radio public service, and cellular communications." "What cumulative leakage index (CLI) meets Federal Communications Commission (FCC) requirements? - Correct Answer 64 or less" "What is the maximum allowable signal detectable in the airspace during a flyover? - Correct Answer 10 uv/m." "CLI calculations do not include leakage below: - Correct Answer 50 uv/m." "Which of the following is a repair order specification when measuring leakage levels? - Correct Answer The location of the leak." "What is the FCC specification regarding repair of leakage of the 20 uv/m level?. - Correct Answer There is no FCC specified time." "A dipole antenna is used for FCC tests because: - Correct Answer Its performance is well characterized." "What are the disadvantages of using an SLM for leakage detection? - Correct Answer Less sensitive than a leakage detector and doesn't have an alarm." "How long must the leakage log be kept on file? - Correct Answer 2 Years." "what leakage level must be entered in the leakage log? - Correct Answer Leaks 20 uv/m or higher measured 10 feet from the cable." "In modern sweep systems, what type of nonintrusive and noninterfering test signal is inserted into the downstream? - Correct Answer Narrow band continuous wave (CW) test carriers, called pulses a frequencies between channels." "How must a directional test point be installed in an amplifier to enable insertion of upstream sweep pulses and view the downstream sweep? - Correct Answer In a path common to the downstream and upstream." "What could cause low-frequency roll-off of the downstream spectrum discovered when sweeping an amplifier? - Correct Answer A loose seizure screw in the downstream path." "When standing waves are displayed in the sweep response, what does the frequency separation between response peaks indicate? - Correct Answer The approximate distance from the test point to the fault." "What do normalized reference traces taken at a fiber-node test point establish? - Correct Answer Baseline sweep responses that are used to balance and sweep all the amplifiers serviced by that fiber-node." "Why is the main downstream output/upstream input port of a distribution amplifier typically the first to be swept in the downstream direction? - Correct Answer To select equalizers and set the output amplitude levels." "If the power out of a transformer must equal the power in, assuming zero efficiency loss, what happens to the output current when the transformed output voltage is 10% lower? - Correct Answer The current increases 10%." "What is the voltage on the secondary of a transformer if the number of secondary windings is 25% of the primary windings? - Correct Answer 25% of the voltage on the transformer's primary." "Which type of rectifier circuit uses two alternating current (AC) waveforms on the transformer secondary? - Correct Answer A full-wave rectifier with a center-tapped transformer secondary." "What term describes changes in output direct current (DC) voltage with changes in input alternating current (AC) voltage expressed as a percentage? - Correct Answer Input regulation." "In a series-pass transistor regulator, which component isolates the Zener diode from changes in the load for improved voltage regulation. - Correct Answer The emitter follower configured transistor (series-pass transistor)." "In a feedback linear regulator, what enables a stable output voltage while enabling a wide range of output current through the load? - Correct Answer The current across the Zener diode is constant." "What characteristic of foldback limiting circuitry protects equipment if the load is accidentally shorted? - Correct Answer The supplied voltage and current drops to near-zero or zero when maximum current limit is reached." "In a basic step-up switcher circuit design, what does the inductor do when the switch is closed and conducting current to ground? - Correct Answer It stores energy in its magnetic field with the current lagging the voltage by 90 degrees." "In a basic step-up switcher circuit design, what is the relationship of the square- wave duty cycle to the output voltage? - Correct Answer The larger the duty cycle, the higher the voltage." "What characteristic of a ferroresonant power supply provides voltage regulation as the source voltage changes? - Correct Answer With the flux in the core saturated, then the secondary voltage remains constant as the primary voltage changes." "What enables set-top boxes (STB) and Data Over Cable Service Interface Specification (DOCSIS) modems to operate as completely separate systems that operate independent of each other? - Correct Answer STB and DOCSIS modems are assigned different upstream channels with dedicated receivers in the headend." "What did the 1.1 version of the Data Over Cable Service Interface Specification (DOCSIS) introduce, incorporating solutions for transporting real-time data applications (such as voice traffic) over the cable operator's managed IP network, and doing so with quality comparable to that of the telephone company? - Correct Answer PacketCable." "What amplitude level should the output of return amplifiers be adjusted? - Correct Answer So that the amplifier gain is equal to the path attenuation that follows the amplifier." "What should be checked if a large percentage of set-top boxes (STB) transmit above 55 dBmV, the upper end of the STB transmission level range? - Correct Answer The value of the attenuator pad at the input of the STB demodulator." "What type of measurement removes any errors attributable to bandwidth and provides an "apples-to-apples" comparison between carriers of differing bandwidths? - Correct Answer The constant power per hertz (power/H2) measurement." "Why are RF return channel carriers unusable for aligning return path equipment? - Correct Answer RF return channel carriers are of short duration and from multiple sources." "Why is 38 MHz typically the highest frequency in the sub-band frequency that is used for upstream modem transmissions? - Correct Answer The upper edge of the sub-band frequency spectrum is prone to group delay caused by the duplex filters." "What enables the set-top box (STB) upstream carrier to be located below 20 MHz and still be reliably received? - Correct Answer The narrow bandwidth and quadrature phase shift keying (QPSK) modulation." "What system is a byproduct of the "funneling effect"? - Correct Answer A many-to-one system." "House amplifiers with a passive return path are used for what type of situation? - Correct Answer For situations when long service drops are used and the forward path needs to be amplified but return path amplification is unnecessary." "Why does the output level from customer premises equipment (CPE) vary? - Correct Answer To compensate for variable amounts of attenuation in the return path of each device." "When calculating return path attenuation in the drop system, what is the attenuation loss through the hot-leg of an unbalanced three-way splitter at sub- split frequencies? - Correct Answer 3.5 dB." "What purpose do diplex filters fulfill when installed at the input and output of a two- way amplifier module? - Correct Answer To route the forward and return signals over different circuit paths to the appropriate section so that they can be amplified separately." "How does the signal attenuation through coaxial cable in the sub-band frequency spectrum compare to the attenuation at forward path frequencies? - Correct Answer At sub-band frequencies, the signal attenuation is significantly less than in the forward path." "What recourse do broadband cable operators have if citizens band (CB) and ham radio signals ingress into their network? - Correct Answer None, as long as the radio transmissions are at or below legal power levels, it is the cable operator's obligation to prevent these signals from entering their network." "How is impulse noise characterized when viewed on a spectrum analyzer? - Correct Answer Impulse noise will appear as random spikes of energy across the entire return path frequency spectrum (5 to 42 MHz)." "How can the amount of thermal noise added to a network be minimized? - Correct Answer By ensuring that the RF input is at or above the specified minimum input level to all amplifiers.." "What location in the network is common path distortion (CPD) most severe? - Correct Answer At the output of a forward amplifier because the forward levels are highest and the return levels are lowest." "What distinguishes a micro-reflection from other types of signal reflections? - Correct Answer In micro-reflections, the echoed signals arrive back at the source with a time delay relative to the incident or transmitted signal, ranging from nanoseconds (ns) to few microseconds (us)." "What are the symptoms of hum on an upstream digital modulation channel? - Correct Answer Bit errors occur, similar to impulse noise and ingress on the upstream path." "Why is it imperative to keep all ingress and impulse noise, even that outside the frequency range of the RF return carriers, to a minimum? - Correct Answer Regardless of the frequency, if the impulse noise or ingress is high enough, it can cause laser clipping." "When looking at a cable modem's PreEqualization Tap response, what do you know if the ninth bar is less than 10 dB below the eighth bar? - Correct Answer That there are high micro-reflections and that the cause is near the modem, likely in the drop system." "What practice can uncover potential return path problems in the drop system that can be mitigated before entering the network? - Correct Answer Prescreening the drop system for ingress or egress." "Why is installing high-pass filters (HPF) at the tap on drops without two-way services considered a short-term solution to ingress and impulse noise migrating into the hybrid fiber/coax (HFC) network? - Correct Answer The HPF will have to be removed when cable modems and digital set-top boxes (STB) are activated at the addresses that have an HPF installed." "What should be done before diagnosing a return path problem in the drop system? - Correct Answer Confirm that the hybrid fiber/coax (HFC) network is working properly." "What spectrum analyzer function is particularly useful as it captures and holds ingress, impulse noise, and other impairments on its display so that they can be viewed and analyzed? - Correct Answer The Max Hold function." "What should be done when the location of electrical interference in the power network is identified? - Correct Answer Notify the power company with the exact location so the cause of the interference can be repaired." "What can be used with a signal level meter (SLM) to check the drop system for RF continuity at sub-band frequencies? - Correct Answer A signal generator" "What information can be gathered by a return path monitoring system that captures the quadrature amplitude modulation (QAM) return channel from a DOCSIS modem? - Correct Answer The group delay, in-band ripple/tilt, and micro-reflections on the QAM channel." "What feature of DOCSIS proactive network maintenance (PNM) can save the technician hours of troubleshooting? - Correct Answer PNM peforms correlation of data from all the modems in an area to pinpoint where the likely problem in the network can be found." "When should a preamplifier be used to measure impairments with a spectrum analyzer? - Correct Answer If the noise floor drops less than 10 dB when the input signal is removed from the spectrum analyzer." "What does the spectrum analyzer Zero Span function do? - Correct Answer The Zero Span function stops the analyzer's sweep and parks its tuner to a specific frequency, displaying amplitude vs. time" "How is laser clipping in the return path characterized on a spectrum analyzer? - Correct Answer By an elevated noise floor above 42 MHz after the optical signal has been converted back to RF typically in the headend." "If a return path impairment appears to be caused by impulse noise, why is it a good idea to begin troubleshooting at distribution taps of 17 dB or lower? - Correct Answer Low value taps have less isolation between ports and offer less attenuation to ingress and impulse noise coming from an individual drop system." "Why are 6 MHz and 41 MHz good choices for test carriers when injecting test carriers into a return path spectrum of 5 MHz to 42 MHz? - Correct Answer These frequencies are at the edges of the return frequency spectrum and are available." "Where should the injected sweep pulses be placed to avoid interference with active return carriers when sweeping the return path? - Correct Answer Between active return carriers only if there is adequate space to accommodate the bandwidth of the injected sweep pulses." "What is reported when the signal level meter (SLM) in a return path alignment system displays the return test carriers as a delta measurement? - Correct Answer The calculated difference between the configured Input and the received input." "When is the return path considered to be properly balanced with unity gain? - Correct Answer When the test carriers injected into the last amplifier in the cascade reach the transceiver in the headend with the same level as from the node." "What should be done about injected test carriers at the node appearing at the transceiver in the headend with frequency response variations of less than 1 dB? - Correct Answer These variations are normal and Can Usually be disregarded," "level, what value equalizer and attenuator pad should be installed if the transceiver reports 3.2 dBmV at 6 MHz and 2.5 dBmV at 41 MHz? Equalizers come in 2 dB increments and attenuator pads in dB increments? - Correct Answer A O dB equalizer, and 3 dB attenuator pad. ( 3.2-2.5=.7)" "Which type of digital modulation contains four symbols with 2 bits in each symbol? - Correct Answer Quadrature phase shift keying (QPSK)," "decimal values can eight bits How many of data represent? - Correct Answer 256" "What is a characteristic of orthogonal frequency division multiplexing (OFDM) channel subcarriers? - Correct Answer They can be modulated at the maximum order of modulation for a given bandwidth that is suitable for the condition of the network." "What media access control (MAC) protocols are specified for digital set-top boxes (STB)? - Correct Answer ALOHA and time division multiple access (TDMA)." "Which advanced Physical Layer (PHY) technology developed and added to DOCSIS 2.0 includes byte interleaving? - Correct Answer Advanced time division multiple access (A TDMA)." "Chipsets with ingress cancellation algorithms are most effective for removing impairments in what portion of the RF return frequency spectrum? - Correct Answer Within the upstream channel bandwidth" "The code words and spreading algorithm of synchronous code division multiple access (S-CDMA) enable simultaneous transmission of up to how many modems on the same RF return channel? - Correct Answer 128" "What happens to the data throughput when transitioning from quadrature phase shift keying (QPSK) to 16-QAM (quadrature amplitude modulation) in a channel of the same bandwidth? - Correct Answer The data throughput doubles." "What access schemes were introduced with advanced Physical (PHY) Layer technologies in DOCSIS 2.0? - Correct Answer Advanced time division multiple access (A-TDMA) and synchronous code division multiple access (S CDMA)." "In a DOCSIS 3.1 orthogonal frequency division multiple access (OFDMA) upstream channel, the average power of the subcarriers are normalized to what bandwidth? - Correct Answer 1.6 MHz." "Which optical band is used for optical amplifiers due to the attenuation loss and availability of economical optical amplifiers? - Correct Answer The C band." "What is one limitation of Fabry-Perot (FP) lasers that is eliminated in distributed feedback (DFB) lasers? - Correct Answer Side modes" "In what applications are avalanche photodiodes (APD) most likely to be used? - Correct Answer In fiber-to-the-home (FTTH) architectures where the high attenuation of optical splitters must be overcome." "Why is the E band undefined for fiber- optics communications? - Correct Answer There is a lot of older fiber cable still in use that may have unacceptable water-peak attenuation." "In the traditional analog return path, what is critical about the upstream optical transmitter? - Correct Answer To make sure the RF level into the upstream transmitter is correct." "In a traditional analog return, the optical detectors are responsive to the power of the received signal. How does the signal level at the output of the upstream receiver relate to changes to its input power? - Correct Answer The signal level at the output of the upstream receiver changes 2 dB for every 1 dB change of received optical power level." "Why is using dBmV, a voltage measurement, acceptable to express the power per Hz power allocation across the channel bandwidth? - Correct Answer Because a constant 75-ohm impedance is being used." "Regarding various optical power meter types, - Correct Answer Enhanced power meters evolved for roles where measurements need to be easily stored, recalled transmitted, and downloaded." "When measuring transmit and receive power with an optical power meter, - Correct Answer The meter's calibration must be traceable to the National Institute of Standards Technology (NIST)." "When measuring end-to-end attenuation, - Correct Answer The light source and optical power meter must be referenced together prior to making any field measurement." "A light source - Correct Answer Is crucial for accurately measuring optical fiber power and attenuation." "When a laser light source is used to test fibers, - Correct Answer A 2 kHz modulation provides a test signal that allows the fiber under test to be detected by an optical fiber identifier." "Optical fiber identifiers - Correct Answer Detect live traffic signals or modulated test signals on an individual optical fiber." "When aligning the optical return path, what are the ideal characteristics of the test signal injected into the upstream optical transmitter? - Correct Answer A noise signal of the same bandwidth to be used for upstream transport" "What evolved after the introduction of switched digital video (SDV) illustrated some limitations of legacy hybrid fiber coax (HFC) networks? - Correct Answer Distributed access architecture (DAA)" "What is it necessary in the optical return path to get the most performance from the DOCSIS 3.1 specification? - Correct Answer Some combination of higher transmit power, more sensitive receivers, and lower path loss." "The proper calibration of test equipment is necessary to ensure accurate measurements. Calibration must be performed using test equipment and signals whose accuracy is validated and traceable to what agency? - Correct Answer The National Institute of Standards and Technology (NIST)." "Specific test equipment is necessary to complete proof-of-performance (POP) tests in the headend. Which piece of test equipment is used for headend POP measurements? - Correct Answer A waveform monitor." "Which calibration is acceptable for FCC proof-of-performance (POP) testing? - Correct Answer By the manufacturer or approved service center." "Why is the use of spreadsheets to detail proof-of-performance test procedures recommended? - Correct Answer Because of the calculations required." "What must occur in a video signal in order to observe the composite triple beat (CBT) on a spectrum analyzer? - Correct Answer The signal must be turned off" "The number of field test points for proof- of-performance tests depends on: - Correct Answer The number of customers," "To minimize the burden on small cable operators, FCC proof-of-performance (POP) testing is required in systems having a minimum of how many customers? - Correct Answer 1,000" "Where should at least one proof-of- performance test point be located? - Correct Answer At the end of the longest cascade," "What guidelines does the FCC specify for how the proof-of-performance (POP) tests are performed? - Correct Answer Proof of good engineering practices and that test procedures are documented" "When performing proof-of-performance (POP) testing, why should a bandpass filter be used during the video signal to coherent beats test? - Correct Answer To eliminate interference generated by the spectrum analyzer itself." "Besides RS-232 ports, what type of interface is common on an optical power meter? - Correct Answer A USB interface can provide easy download of information to a PC." "Optical power meters used for testing fiber-to-the-user (FTTX) installations operating downstream from the headenc should be calibrated for which wavelengths? - Correct Answer 1,490 nm, 1,550 nm, and 1,577 nm." "A wavelength-isolating power meter is most commonly used in - Correct Answer Point-to-multipoint FTTX installations." "Optical loss test sets perform multiple functions because they include the features of multiple pieces of test sets The features of which other test sets a combined into an optical loss test set? - Correct Answer A stabilized light source, an optical return loss meter, an enhanced A stabilized light source, an optical return meter, an enhanced optical power meter, and an optical talk set."