NCTI Tech I to Tech II

A troubleshooting flowchart is a sequence of events, and questions. A field technician is dispatched on a trouble call for tiling. What is the first question the technician should ask himself?

"Are there similar complaints from other customers?" is the first question the technician should ask himself when dispatched on a trouble call for tiling. This is actually true of any service problem, not just tiling.

What is the mean opinion score (MOS) grading scale?

5 - Perfect. 4 - Fair; imperfections can be seen but they are not too common as to be irritating. 3 - Artifacts appear often enough to be annoying. 2 - Very annoying; nearly impossible to watch anymore. 1 - No image.

How does a Multimedia over Coax Alliance (MoCA) filter alleviate potential problems with the MoCA service?

A MoCA filter alleviates potential MoCA service problems by keeping interference from MoCA signals inside as well as outside the premises wiring, it creates a strong MoCA signal through advantageous reflections, and mitigates harmful reflections from distant non-compliant devices.

What could cause an initialization failure that is signaled by the DS indicator?

A failure during downstream scanning occurs when there is either no DOCSIS carrier or the DOCSIS carrier is not being recognized by the modem because of low amplitude or impairments or degradation to the carrier.

Are certain features included in specific version releases of High-Definition Multimedia Interface (HDMI) guaranteed to work?

A particular HDMI version does not guarantee a particular set of features because features are optional for the manufacturer.

How do a short, an open, and a ground fault disrupt dial tone?

A short anywhere in the telephone wiring will result in no dial tone to all CPE. An open in the telephone wiring will result in selected pieces of equipment having no dial tone, depending on the location of the fault in the circuit and the wiring topology. A ground fault will disable the ability of the network or EMTA to supply dial tone.

When does a split pair occur?

A split pair occurs when the tip (positive conductor) or ring (negative conductor) of one pair is connected to the tip or ring of an adjacent pair.

What does a transpositionor miswire indicate?

A transposition or miswire indicates the improper assignment of individual wire pairs to pins for the wiring scheme tested.

What is the residential phone wiring configuration according to ANSI/TIA/EIA 570-B?

According to ANSI/TIA/EIA 570-B, wiring must be solid No. 24 AWG or larger copper, and twisted-pair cable must comply with the electrical specification of category 5e (CAT-5e) or greater.

After the technician has made appropriate repairs, what is the final step they need to take?

After the technician has made appropriate repairs, they need to verify that the repairs have actually resolved the problem.

What should be done if a cable modem analyzer experiences an interruption during provisioning with the cable modem termination system (CMTS)?

Any interruption to a provisioning step can be diagnosed using information from the cable modem analyzer's status field.

What do artifacts resulting from cable distribution network impairments have in common with one another?

Artifacts resulting from cable distribution network impairments are the result of lost or corrupted data, which result in excessive bit error rate (BER) and poor modulation error ratio (MER).

What is the value in substituting the cable modem analyzer for a cable modem?

As a substitute modem, the analyzer can help determine whether a modem is defective or if the problem is with the computer without going through the process of provisioning another modem.

What does asymmetric data throughput mean?

Asymmetric data throughput is a term that describes the downstream data throughput as being significantly higher downstream than upstream.

What can you locate with audible clicks or other sounds on the telephone test set?

Audible clicks or other sounds on the telephone test set can locate the existence of short and open circuits.

Why is a throughput measurement test a valid measurement of a network's performance?

Because throughput can be compromised by traffic congestion and errors introduced during transport, the throughput measurement is an effective measurement of the network's technical integrity.

What is the difference between the broadcast and multicast addressing schemes?

Broadcast is a one-to-all addressing scheme in which one device sends the same stream of data to an address that all connected devices can receive. Multicast is a one-to-many addressing scheme in which one device sends a stream of data only to specifically addressed devices on the network.

What can be done to keep recorded programming from being overwritten by new recordings?

Change record settings in the set-top box (STB) to keep recorded programming from being overwritten by new recordings.

In what position do you connect the modular test lead on the 77HP?

Connect the modular test lead with the 77HP in the "Tone" position.

What are the most common digital video points of failure prior to the video signal entering the distribution network?

Corrupted digital data received at the headend from the source, over-compression, statistical multiplexing, rate shaping, and signal levels are all possible points of failure for digital video prior to the signal entering the distribution network.

What are the four IP provisioning modes available for DOCSIS 3.0 and 3.1 modems?

DOCSIS 3.0 modems can be provisioned to operate in one of four IP modes: IPv4, IPv6, alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).

Which DOCSIS version provided the option to increase the top frequency of the upstream to 85 MHz, and bumped the downstream range to 108 MHz to 1,002?

DOCSIS 3.0 provided the option to increase the top frequency of the upstream to 85 MHz, and bumped the downstream range to 108 MHz to 1,002 MHz.

What information should be gathered before beginning to troubleshoot a high-speed data (HSD) problem?

Discuss the problem with the customer and then ask them to demonstrate the problem they are experiencing so that you can view the symptoms and assess the problem, taking note of any unusual screens or customer entries.

What type of questions should the technician ask the customer during the identify and analyze stage of the six-step troubleshooting process?

During the identify and analyze stage of the six-step troubleshooting process, ask the customer about any work done on the premises and about any unusual events such as power outages or electrical storms prior to the problem, and if anyone has tried to fix the problem already.

How does environmental damage to UTP cable occur?

Environmental damage to UTP cable occurs when system components are subject to water, dirt, oil, sunlight (ultraviolet), air pollution, rodents, and so on.

How does a receiver know the bit error rate (BER) of a digital modulation carrier?

Forward error correction (FEC) data is added to the original data stream during modulation so that the receiver can detect and repair bit errors.

Which step in the six-step troubleshooting process requires a discussion with the customer to gather more detail about the problem?

Identifying the problem, the first step in the troubleshooting process, requires a discussion with the customer to gather more detail about the problem, such as the time of day that the problem occurs.

What is the value of the cable modem status indicators?

If a cable modem is unable to complete its provisioning, the modem status indicators can help pinpoint the cause of the problem.

What are some of the probable causes of a situation where a customer has a picture but no sound?

If a customer has a picture but no sound, the sound could be muted on the STB or the TV set, the volume could be set too low, the cables or connectors could be installed incorrectly, the headphones could be connected, the STB could be improperly configured for audio output, or the surround sound system may not be powered up or may be faulty or improperly configured.

What should be checked if an embedded multimedia terminal adapter (EMTA) signals the presence of foreign voltage on the TELEPHONE 1 port when the telephone lines are connected?

If foreign voltage on the telephone line is suspected, immediately disconnect the line from the EMTA and check the network interface device (NID) to ensure that the lines from the previous telephone provider are disconnected.

What is the significance of the REN rating when diagnosing a telephone ringer problem?

If the total REN of the telephones, fax machines, etc., connected to one telephone line exceeds the REN of the service, some or all of the ringers may not operate.

How many pixels are color-averaged in a 4:2:2 profile?

In a 4:2:2 profile, the colors from two pixels are averaged together and the resulting color fills those two pixels.

Which layers of the seven-layer Open Systems Interconnection (OSI) reference model are present in the DOCSIS implementation?

In the DOCSIS implementation of the OSI reference model, Layers 1 through 4 are specific to cable networks and are present only between the cable modem and the CMTS.

List several causes of digital video impairments in a cable distribution network.

Incorrect signal levels leading to noise and distortions, CPD (common path distortion) caused by corroded connections, ingress noise due to cracked cables or high-power intermittent noise, impedance mismatches due to unterminated taps causing reflections, defective equipment, cable and connector faults, and lack of proper grounding are all causes of digital video impairments in a cable distribution network.

What should be done if a transposition error is discovered when using a twisted-pair cable tester to locate a fault in a premises that is cabled in the star topology?

Inspect the wiring order at the local connector before going to the opposite end and perform the same task. When cabled in the star topology, repeat the same process for each cable by moving the tester remote unit to each room that has a data outlet until all the cables have been tested.

What forms of compression are intraframe and interframe coding?

Intraframe coding is a form of spatial compression and interframe coding is a form of temporal compression.

List likely causes of remote control problems?

Likely causes of remote control problems include: (1) A blocked line of sight between the remote control and the set-top box (STB); (2) a defective STB; (3) weak or dead batteries in the remote control; (4) a deprogrammed remote control; or (5) a defective remote control.

What requirement do many cable operators have when high-speed data (HSD) and Internet protocol (IP) voice service is installed?

Many cable operators require that outlets providing signals to Data Over Cable Service Interface Specification (DOCSIS) modems or embedded multimedia terminal adapters (EMTA) undergo a series of measurements which certify the outlets as compliant in delivering and transporting DOCSIS carriers.

How is the bit error rate (BER) of a digital modulation carrier displayed on most digital signal analyzers?

Most digital signal analyzers display the BER in scientific notation. BER is the number of bits in error received, divided by the total number of bits received. For example, 1.0E-6 equals one error per million bits received and 1.0E-9 equals one error per billion bits received.

What is the advantage of using the cable modem analyzer to measure modem performance parameters instead of using a computer connected to a modem?

Most modem analyzers provide detailed information that is not available when running comparable measurements from a computer, plus, the modem analyzer is portable and battery powered, which is relatively easy to carry into the backyard and connect to a tap or other location in the network.

In the wiremap test, what does no continuity (open faults) indicate?

No continuity (open faults) in the wiremap test indicates a broken conductor, a missed termination in a connector or jack, or a mismatched connection (for example, T568A termination on one end and T568B on the other end).

What can be done at the customer premises to reduce the effects of ringing and contouring artifacts?

Nothing can be done at the customer premises to reduce the effects of ringing and contouring artifacts because these artifacts are caused by digital video processing, before the video signal enters the cable distribution network.

How will the green LEDs sequence on a correctly terminated cable?

On a correctly terminated cable, the green LEDs will sequence from 1 to 4 on both units.

What is the difference between on-network and off-network programming?

On-networking programming is under the control of the cable operator and off-network programming is not under the control of the cable operator as it arrives at the customer location via the Internet.

What does open indicate?

Open indicates a break in the electrical path.

What are perceptual quality metrics (PQM) used for?

PQM are objective metrics of human visual perception based on statistical analysis of quality of service measurements and MPEG encoding data.

What does pass indicate?

Pass indicates that the cable tested is correctly "pinned" and electrically continuous without open or short circuit conditions.

What does placing the T/M switch of the Harris TS21 in the "T" position establish?

Placing the talk/monitor (T/M) switch of the Harris TS21 in the "T" (talk) position establishes an off-hook condition for dialing and talking.

What problems can be caused by using a USOC wiring configuration on a modular plug or jack used for data?

Problems caused by using a USOC wiring configuration on a modular data plug or jack include excessive crosstalk, impedance mismatches, and an unacceptable signal delay differential.

What is the benefit of using quality of experience (QoE) compared to quality of service (QoS)?

QoE is a subjective perception of digital video quality, whereas QoS is a measure of objective network data.

What are the two types of telephone station wiring typically installed in customer premises?

Quad station wire and unshielded twisted-pair (UTP) cable are the two types of station wire typically installed in customer premises.

What digital video artifact, caused by some customer premises equipment, is never a factor with plasma displays?

Response time is not a factor for plasma displays. Illuminated pixels follow a cycle of charge, activation, and discharge. The pixel is dark during discharge, which clears the retina of the last image.

What does reversal for telephone wiring mean?

Reversal means that the tip and ring wires at the main unit jack are switched at the remote jack. The tip and ring pin assignment will depend on the specific wire configuration.

What circuit condition in the telephone wiring can prevent touch-tone telephones from transmitting the DTMF tones used for tone dialing?

Reverse polarity in the telephone wiring can prevent some touch-tone telephones from transmitting the DTMF tones used for tone dialing.

What does short indicate?

Short indicates a short circuit condition exists.

Although capable of delivering a high-definition (HD) signal, what are some limitations of a component video signal?

Some limitations of a component video signal are that it is analog, it requires manual adjustment of resolution settings between the STB and TV set, and it may not provide an HD signal out of some Blu-ray players manufactured after 2010.

At the customer viewing location, there is customer premises equipment (CPE) that commonly causes digital video artifacts. Name some of these devices:

Some of the equipment at the customer viewing location that can cause digital video artifacts includes substandard and faulty hardware, substandard cables and connectors, faulty cables and connectors, poorly adjusted equipment, less-than-optimum wiring schemes, and faulty connections inside and outside of equipment.

Which pinning configuration should be used when 8P8C modular connectors are installed on cables used for connecting computers and modems to the local area network (LAN)?

Straight-through pinning is used when 8P8C modular plugs are installed on cables used for connecting computers and modems to the local area network (LAN).

What are telephone test sets used for?

Telephone test sets are used to monitor the telephone line, check line polarity, place and receive calls, and troubleshoot various faults.

What does the "M" position on the Harris TS21 allow?

The "M" position on the Harris TS21 allows line monitoring without disrupting conversations, data, or signaling.

How many bits are used in Internet protocol version 6 (IPv6)?

The 128-bit numbering scheme of IPv6 yields approximately 3.4 × 1038 addresses.

What two device functions are combined within an embedded multimedia terminal adapter (EMTA)?

The EMTA combines the functions of a DOCSIS cable modem and a multimedia terminal adapter (MTA) within a single element.

What does the Ideal PathFinder test for?

The Ideal PathFinder tests wiring configurations, wiring, and connection faults, including reversals, opens, shorts, transpositions or miswires, and split-pair conditions.

What does the Progressive Electronics 468 Modular cable tester confirm?

The Progressive Electronics 468 modular cable tester confirms proper or indicates improper termination of two-, four-, six-, and eight-conductor modular voice and data cabling.

What happens to an set-top box (STB) after it is plugged in?

The STB heats up after it is plugged in, which changes its performance.

What information can be obtained from the adaptive equalizer taps displayed in the digital signal analyzer?

The adaptive equalizer taps can be used to determine the presence and estimate the location of reflections caused by bad connectors or damaged coaxial cable.

What are the main components in the Data Over Cable Service Interface Specification (DOCSIS) architecture?

The cable modem and the cable modem termination system (CMTS) are the main components in the DOCSIS architecture.

Where is a logical place to begin applying the divide-and-conquer method to an HSD problem in the customer premises?

The cable modem is the logical place to begin using the divide-and-conquer method to identify where an HSD problem originates in the customer premises.

What are the characteristics of a successful troubleshooter? Please provide a few more of your own.

The characteristics of a good troubleshooter include the desire to solve problems and fix things, the know-how to use a variety of pieces of test equipment, accuracy in documenting measurement results, and the pride in your work that prevents you from settling for marginal results.

List some reasons why a customer may not be able to order video-on-demand (VOD).

The customer's credit limit has been reached, the customer's account is in a delinquent status, the proper service codes have not been downloaded to the STB, there are problems with the forward or return signals all are reasons that may keep a customer from ordering VOD.

What process must the digital signal analyzer perform to analyze the digital signal?

The digital signal analyzer must first decode the digital content to analyze the modulated digital signal.

In which of the six stages of troubleshooting is the divide-and-conquer method executed?

The divide-and-conquer method is executed in the "isolate the elements" troubleshooting stage.

Determining whether the cause of a problem is to one side or the other of a specific device describes what type of troubleshooting method?

The divide-and-conquer method of troubleshooting determines whether a problem is to one side or the other of a particular device.

Why do some cable operators choose to perform automated measurements on a sample of channels rather than all channels transported through the network?

The execution of automated measurements can take several minutes, so some cable operators choose to perform automated measurements on a sample of channels rather than on all channels transported through the network.

What is the first step in testing wiring configurations?

The first step in testing wiring configurations is to determine which configuration (USOC or T568A/B) you are testing.

What are the four most common types of telephone line noise?

The four most common types of telephone line noise are: (1) static; (2) hum; (3) crosstalk; and (4) radio interference.

What is the intent of the Commercial Advertisement Loudness Mitigation (CALM) Act?

The intent of the CALM Act is to keep TV commercials from being louder than the associated television program.

How can the digital signal analyzer's constellation display be used?

The pattern of the constellation display and the clouds around the data symbols can be used to interpret and diagnose modulation errors.

What is the relationship between adjacent orthogonal frequency division multiplexing (OFDM) subcarriers?

The peak power of each OFDM subcarrier aligns with the minimum power of the adjacent subcarrier, or orthogonal.

Why would the provisioning of a cable modem analyzer differ from that of a cable modem?

The provisioning of a cable modem analyzer may differ from a cable modem if there are special restrictions, permissions, or privileges assigned during provisioning to accommodate the cable modem analyzer's use throughout the network.

At what modulation error ratio (MER) does the reception of a 64-QAM and 256-QAM carrier begin to degrade?

The reception of a 64-QAM carrier begins to degrade around 22 dB MER, and a 256-QAM carrier begins to degrade around 28 dB MER, but a 4 dB margin in MER is recommended to assure error-free reception.

When considering which types of signal impairments can cause tiling artifacts on a digital video channel, in what step of the six-step troubleshooting process is the technician is most likely use?

The technician is most likely to use Step 2. Analyzing the Situation, when considering which types of signal impairments can cause tiling artifacts on a digital video channel.

What do the test result indicators include?

The test result indicators include pass, reversal, open, short, transposition or miswire, and split pair.

What type of test equipment is designed specifically to test and diagnose twisted-pair cable?

The twisted-pair cable tester is designed specifically to test and diagnose twisted-pair cable and its connections.

What are the four major components of a telephone circuit in the customer premises?

The voltage/signal source, consisting of the NID/EMTA, the station wiring, the terminations, such as connectors, plugs, and jacks, and the CPE are the four major components of a telephone circuit in the customer premises.

What can cause the data throughput speeds to vary at different times during the day?

Throughput speeds can vary during the day depending on the level of network activity and the amount of data being transported to and from end users.

Using the 200EP, how do you confirm the wire identification?

To confirm the wire identification, touch the tip of the 200EP to the signal-carrying conductor.

How do you test for faults using the Progressive Electronics 468 cable tester?

To test for faults using the 468 cable tester, switch on the transmitter power switch on the side of the transmitter to test the modular telephone or data cable and four-, six-, or eight-position male plug termination connecting to the 468 cable tester.

How does troubleshooting an Internet protocol (IP) voice installation differ from troubleshooting a trouble call?

To troubleshoot an installation, the technician must identify and analyze the problem rather than discussing the problem with the customer as they would during a trouble call.

How can transpositions occur?

Transpositions exist when a complete pair of wires are accidentally terminated where another pair should be terminated. This error is typical when an installer terminates one end of an installation in the T568A configuration and the other end in the T568B configuration.

What is the best way to tell if a basic digital-to-analog converter is defective?

Try the suspect converter on a different outlet or install a known "good" converter on the suspect outlet and see if it works. If it works on the second outlet, then the original outlet must be repaired. If the known "good" converter works on the original outlet, then the original converter is defective.

Name two telephone test sets.

Two telephone test sets are the Lil' Buttie Pro test set and the Harris TS21 craft test set.

When using a digital video interface (DVI) connection and there is no audio, what is a likely cause?

Unlike RF or High-Definition Multimedia Interface (HDMI) connections, DVI connections requires a separate audio connection.

List the functions of a tone generator and inductive amplifier probe when used together.

Used together, a tone generator and inductive amplifier probe: (1) perform a telephone line test/polarity test; (2) perform a continuity test; and (3) confirm wire identification at the network interface device (NID), EMTA, the distribution device, a cross-connect point, or the modular telephone jack.

Using the Ideal PathFinder cable tester, how do you test for faults after selecting the desired wiring configuration?

Using the Ideal PathFinder cable tester to test for faults after selecting the desired wiring configuration, push the "Mode" button to proceed to pass/fail and observe the "Config" LED.

When checking line polarity with a Harris TS21, when does the green LED light up?

When checking line polarity with a Harris TS21, the green LED lights if the red test lead is connected to the ring (negative) side of the line and the black test lead is connected to the tip (positive) side of the line.

When adjusted to the same power level, why does a digital signal appear to be of lower amplitude than an adjacent video carrier when displayed on a spectrum analyzer?

When set to the same power level, the digital signal appears to be at a lower amplitude than the adjacent video because the digital signal is adjusted by the average power of the signal. The video signal is set using the peak envelope power of the video carrier.

When testing the USOC wiring configuration, pair _________ is the default pair ready to test.

When testing the USOC wiring configuration, pair 1 is the default pair ready to test.

What the maximum possible throughput in the downstream when eight, 256-QAM channels are bonded?

With a throughput of 38 Mbps in a 256-QAM channel, the maximum throughput for eight bonded channels is: 38 Mbps × 8 = 304 Mbps.

Which pins on a modular plug breakout adapter should show low resistance on a DMM, when using a shorted modular plug to verify connectivity of pairs in UTP cable?

With the shorted modular plug connected, pins 4 and 5 (pair 1), 3 and 6 (pair 2), 1 and 2 (pair 3), and 7 and 8 (pair 4), all should measure near zero ohms of resistance on a DMM.

What do each of these LED colors on a tone generator indicate for line status and polarity: (1) bright green; (2) bright red; (3) dim green or red; (4) bright green or red flashing, that may appear yellowish; and (5) no LED lights?

A bright green LED indicates a clear working line with correct polarity. A bright red LED indicates a clear working line with reversed power polarity. A dim green or red LED indicates a clear working line that is in use with correct or reverse polarity, respectively. A bright green or red flashing LED, that may appear yellowish indicates a ringing line. No LED lights indicate an open line, a line pair that has no power, or a nonoperational line.

How is availability different from reliability?

Availability is the ratio of time that a device, system, network, or service is available for use to total time. Reliability is the probability that a system or device will not fail during a specified period.

What information can be obtained from the Internet protocol (IP) voice analysis function in a signal level meter?

The IP voice analysis function provides information regarding the voice data packets that are transmitted and received by the embedded multimedia terminal adapter (EMTA), such as latency, jitter, and calculated mean opinion scores (MOS).

Why is the embedded multimedia terminal adapter (EMTA) a good place to begin the isolation step of troubleshooting an Internet protocol (IP) voice problem?

The is the interface between the hybrid fiber/coax (HFC) network and the telephone equipment in the customer premises, which makes the EMTA a logical place to begin the isolation process when troubleshooting an IP voice problem.

Which function does the tester use to locate opens?

The length measurement function is used to locate an open.

What are the three major topologies used for unshielded twisted-pair (UTP) cable installations?

The three major topologies for installing UTP cable are: (1) the star topology; (2) the bus topology; and (3) the hybrid topology.

Using the Lil' Buttie Pro, how do you listen to the telephone line without loading it and interrupting data transmissions and voice conversations?

To listen to a telephone line with the Lil' Buttie Pro test set without interrupting data transmissions and voice conversations, push the talk-bell-monitor (TBM) switch down to the "Monitor" position.

Using the telephone test set, how do you locate a short circuit?

To locate a short circuit using the Harris TS21, open one side of the telephone line and place the test set in the loop — one lead to each side of the opened line.

Using the telephone test set, how do you locate an open circuit?

To locate an open circuit using the Harris TS21, bridge the test set across the circuit line — one test lead on the tip, the other on the ring.

To perform any basic telephone line test/polarity test, use the 77HP tone generator in the "___" position.

To perform any basic telephone line test/polarity test, use the 77HP tone generator in the "Off" position.

How do you place the Lil' Buttie Pro in the talk position?

To place the Lil' Buttie Pro in the talk position, push the TBM switch up in the "Talk" or off-hook position, then read the dialing mode, the measured off-hook line current in milliamperes, and the line polarity (NRM or REV).