ncti 2, NCTI jones, ROC II, Course 1, NTCI: Troubleshooting Advanced Services
Converted into a digital DS0 circuit and switched to other cable telephony customers or to the telephone company's network.
A constant bit rate (CBR) telephone system is considered to be circuit-switching technology because the analog audio signal is
A symbol.
As the level of modulation increases, so does the number of bits that are represented by a signal transition. What are transitions representing more than one bit known as?
MPEG-2.
Each of the MPEG standards describes a specific part of the digital coding process. Which standard describes the data transport process?
Jitter.
In cable telephony, latency is a measure of the delay of the system. What term is used to describe how much the latency varies?
When making the upstream connection.
There are three defined connections in proper sequence that a Data Over Cable Service Interface Specification (DOCSIS®) modem must make for operation. At which point does the modem begin the ranging process to establish communications between the modem and the cable modem termination system (CMTS)?
Third generation (3G).
Which of the following technologies allows Internet access for mobile phone users?
the attribute of being active as a critical thinker means?
you observe and take notes relevant to the issue
Regarding digital video quality at the customer premises,
(QOS) metrics are important to help identify potential problems before they can affect a customer's more subjective (QOE).
How many home network devices categories have been defined by the DLNA?
, dms, dmp, dmr, dmc, dmpr
what kind of reasoning is described as applying a general statement that you know to be true to a new situation?
-deductive
how does internet protocol multicast differ from broadcast?
-multicast traffic is only sent to specific modem addresses on the network, broadcast is sent to all modems on the network
When using a digital signal analyzer to troubleshoot data throughput in the DOCSIS network, what is the minimum modulation error ratio (MER) into the cable modem for a 256-QAM carrier?
32 dB or greater.
Modulation error ratio (MER) is an indicator of digital modulation signal quality. For error-free reception and adequate margin, what should be the minimum MER reading fro a 256-quam signal?
32 dB.
when using a digital analyzer to troubleshoot data throughput in the docsis network, what is the minimum modulation error MER into the cable modem for a 256 QAM carrier
32Db or greater
how many upstream channels can be bonded in docsis 3.0?
4 upstream
When you use a digital analyzer to examine a digital signal, one of the values you should check is the symbol rate. What should the symbol rate setting for a 256-QAM signal specified by the (ITU) in ITU-T J.83 Annex B?
5.360537 megasymbols per second (MS/s)
What would be the downstream throughput if two 256-QAM channels with a throughput of 38 megabits per second (Mbps) were bonded?
76 Mbps.
. what would be the downstream throughput if 256 quam channels with a throughput of 38 mbs were bonded?
76 mbs
which release of the institute of electrical and electronics engineers 802.11 specification was the first wireless accepted wireless standard to be branded with the wifi name?
802.11
Bit error ratio (BER) is one of the measurements a technician used to determine how well the network is operating. What is the acceptable post-BER at the end of the drop?
<1.0E-9.
In addition to being accurate and detailed, a successful troubleshooter knows that...
A critical step in troubleshooting is verifying the signal levels and signal quality at the tap to establish the baseline performance for the installation.
Analyzing the problem further to get a more narrow definition of the issue before trying to diagnose the symptoms of the problem.
A logical progression of events for resolving a customer's report of digital video artifacts on various channels could include
Adds null packets to the adaptation field.
A multiplexer ensures that all transport stream packets are 188 bytes. What does the multiplexer do when the header and the payload do not equal 188 bytes?
Describe the difference between a "short" and a "cross" in unshielded twisted-pair (UTP) cable.
A short is an undesired electrical connection between the paired wires. A cross is the term for when the connection is complete to the proper terminals, but either wire of one pair shorts to either wire of another pair.
Although off-network programming is not the responsibility of a cable operator.
A technician needs to understand that customers viewing video through the internet may report problems with a video program that has not been scrutinized by the cable operator.
Which of the following scenarios describes the hybrid wiring topology?
A three-bedroom house: The master bedroom telephone jack is connected directly to an EMTA, and bedrooms two and three are fed from the master bedroom telephone jack.
The sync byte field.
A transport stream contains an information table that is necessary for a decoder to sort data and reconstruct a program. In a transport stream header, which field is used by the decoder to indicate the beginning of a transport stream packet?
What is the term for the error caused when one end of an unshielded twisted-pair (UTP) cable is terminated in the T568A configuration and the other end in the T568B configuration
A transposition.
What is a limitation of using the shorted modular plug for testing the wiring of a modular connector?
A wiring error such as a transposition can go unidentified because each pair is terminating into the same value of resistance, which is a short.
Parity.
ASCII is a seven-bit binary data code. In practice, however, it is coded with eight bits. What is the 8th bit used for?
A technician needs to understand that customers viewing video through the Internet may report problems with a video program that has not been scrutinized by the cable operator.
Although off-network programming is not the responsibility of a cable operator,
By measuring the average power from the carrier's center frequency to both carrier edges.
Amplitude measurements are obtained differently on analog and digital quadrature amplitude modulation (QAM) carriers. How are amplitude measurements on QAM digital carriers obtained?
You have a cable modem analyzer and you want to replace the cable modem to determine whether the modem is bad. How should the modem analyzer be connected to replace the modem?
An Ethernet cable is connected from the cable modem analyzer to the customer's computer, and the RF drop input cable is connected to the cable modem analyzer.
Interframe coding, a form of temporal compression, uses...
An intra-coded frame to compare picture information between consecutive frames, using motion vectors, which results in predicted frames (P-frames).
Perceptual quality metrics (PQM) provide cable operators with...
An objective measurement of human visual perception based on a statistical analysis of quality of service (QOS) measurements and MPEG encoding data.
What is the likely problem when there is dial tone on one phone connected to an outlet, but not on two other phones connected to two different outlets?
An open circuit caused by a break in a conductor, poor contact in a modular connector, or an incorrect wire connection.
A logical progression of events for resolving a customer's report of digital video artifacts on various channels could include...
Analyzing the problem further to get a more narrow definition of the issue before trying to diagnose the symptoms of the problem.
Tiling, missing audio, and picture are examples of artifacts that...
Are likely under control of the technician in the hybrid fiber/coax (HFC) network or at the customer premises.
In walking through the flowchart for the six-step process of troubleshooting a report of tiling by a single customer, one of the first questions asked should be...
Are there similar complaints from other customers?
<1.0E-9.
Bit error rate (BER) is one of the measurements a technician uses to determine how well the network is operating. What is an acceptable post-BER at the end of the drop?
Two true inputs.
Boolean logic is a form of algebra in which all values are reduced to either true or false. In a NAND gate, which of the following inputs would produce an outcome of false?
Four.
Both carriers in quadrature phase shift keying (QPSK) are amplitude modulated with half of the data stream, then combined together to produce the QPSK symbol. How many amplitude and phase states does a QPSK signal use?
The telephone wiring is in the bus topology and the twisted-pair cable tester is connected at the EMTA, with the remote unit connected to the last outlet in the loop. If the tester indicates a wiring error, what is the quickest way to locate the incorrectly wired outlet?
Break the loop into smaller sections and retest the two sections to identify which one has the wiring error. Continue to divide the section with the error into smaller sections until the wiring error is identified.
American National Standards Institute (ANSI)/Telecommunications Industry Association (TIA)/ Electronic Industries Alliance (EIA).
Businesses often have a room that contains the cables and equipment for telephone communications. Which standards are used for the telephone room requirements?
Phase shift keying (PSK).
By definition, modulation is the process of altering the amplitude, frequency, phase or some combination of these characteristics of the continuous wave (CW) carrier by the coding of a baseband signal. In what type of modulation is the frequency and amplitude the same for a one or zero
To determine if objective network data measured by quality of service (QOS) parameters match a customer's overall satisfaction level...
Cable operators use a quality of experience (QOE) measurement based on mean opinion score (MOS) and perceptual quality metrics (PQM).
Authorizing encrypted video services.
CableCARDs have two primary functions. One is user authentication. What is the other function?
When troubleshooting telephone service in the customer premises, what is the next step if there is no dial-tone voltage at the telephone outlet?
Check for voltage at the embedded multimedia terminal adapter (EMTA); if no voltage is present, the problem is either the network signal entering the EMTA or the EMTA is bad.
If a customer reports that a program's audio plays but there is no video display, the recommended actions are...
Check if any cables are disconnected, make sure the TV set is properly configured, and check to see if the TV in on (if audio runs through a different system such as surround sound).
If a digital video service customer reports that the set-top box does not respond to the remote control, what is the quickest and easiest thing to do first?
Check the line of sight between the remote control and the set-top box.
To eliminate possible causes of audio issues, a technician can...
Check the set-top box and the television set to ensure audio connections have been made correctly.
Compressing a raw digital video file so that each pixel retains its own luminance information, but the chrominance is averaged from the original pixel pairs to a 4:2:2 profile.
Chrominance subsampling, which usually takes place in the studio environment, is the process of
In-channel ingress.
Coherent interference causes the constellation display to look like a series of small donuts. What is one cause of coherent interference?
In a DOCSIS network, why is the data throughput over the return or upstream path typically less than the throughput of data over the forward or downstream path?
Compared to the downstream path, the narrower bandwidths and lower orders of modulation used to transport data over the return path cause the downstream and upstream data throughput to be unequal or asymmetrical.
Chrominance subsampling, which usually takes place in the studio environment, is the process of...
Compressing a raw digital video file so that each pixel retians its own luminance information, but the chrominance is averaged from the original pixel pairs to a 4:2:2 profile
The downstream carrier.
Data Over Cable Service Interface Specification (DOCSIS®) modems require both the downstream and upstream portions of the hybrid fiber/coax (HFC) network to be working properly. Signal levels, modulation error ratio (MER), and bit error rate (BER) measurements should be taken to troubleshoot what?
In troubleshooting a digital-to-analog converter, try the suspect converter in a different, working outlet to...
Determine if the original outlet needs to be repaired.
The cliff effect.
Digital receivers are resistant to noise until the number of impairments on the system reach the point where the receiver can no longer detect the digital signal. What is this known as?
Service authorization, received signal quality, and return path operations.
Digital set-top box diagnostics can aid a technician with which of the following parameters while troubleshooting?
Tiling.
Digital video problems can be caused by a loss of data to the receiver or by over-compressed content data. Which digital video problem can be recognized by blocks of video information, in the shape of squares or rectangles that are missing or incomplete on the display?
if the customer demonstrates that they are internet savy, what should be the next step in the customer education portion of the high speed data server installation?
Direct the customer to the cable operators web page to show them what information is available and to help them setup their email
What must be done before using a twisted-pair cable tester to diagnose unshielded twist-pair (UTP) cable wired in the star topology inside the customer premises?
Disconnect all customer premises equipment (CPE) from all the jacks in the customer premises.
what version of the docsis specification included the option to increase the tap frequency of the upstream to 85 Mhz?
Docsis 3.0
the use of a directional coupler requires which of the following adjustments in the return paths?
Each return amplifier must be adjusted so that the levels received at the next amplifier are within 15 db of eachother
During the modulation stage.
Error correction data enables the receiver to restore bits of data lost during transmission, and reconstruct the original content. At what stage is the error correction data inserted?
Decibels per millivolt per hertz (dBmV/Hz).
Errors can be avoided when measuring signals of different bandwidth by converting all measurements to a common value-per-frequency unit. What measurement removes any errors attributable to bandwidth and allows for comparisons between signals of differing bandwidths?
Why does it take a few minutes for a cable modem analyzer to become functional once connected to the network?
Every time the cable modem analyzer function is enabled, the instrument performs a self-provisioning of the instrument's internal modem which enables communication with the cable modem termination system (CMTS).
When can the T568A wiring configuration, recommended in ANSI/TIA/EIA 570-B, be used for installing (8P8C) modular plugs and jacks for residential telephone service?
For telephone only installations that do not include data connections.
When equipment is connected via the component video output...
Format settings for vertical resolution, scan method, and aspect ratio may need to be adjusted manually.
A network comprised of several local area networks (LAN) and metropolitan area networks (MAN) interconnected into a single network covering a large geographic area
Generally speaking, a wide area network (WAN) can be described as
Equipment in the central office for POTS senses the change in voltage and generates a dial tone where the EMTA senses the change and generates a dial tone in PacketCable.
Generating a dial tone in either a traditional telephone call or a PacketCable voice over Internet protocol call is similar, except
Add-drop multiplexing.
Grooming is one method used to control the content sources on a hybrid/fiber coax (HFC) network. What is grooming also referred to as?
The audio and video packets are separated.
High definition television uses several processes to take the data sent by the cable company and display it on the television set. What happens to the data when it is demultiplexed?
From a dynamic host configuration protocol (DHCP) server that provides the CMTS with the modem's IP address, which is forwarded to the modem during initialization.
How does a DOCSIS modem receive its Internet protocol (IP) address?
What information about the digital carrier can be learned by accessing the adaptive equalizer function of the digital signal analyzer?
How much the adaptive equalizer has to compensate for linear distortions of the digital carrier.
How does IP multicast differ from IP broadcast?
IP multicast traffic is only sent to specific modem addresses on the network, IP broadcast traffic is sent to all modems on the network.
What internet protocol (IP) address modes can a DOCSIS 3.0 and 3.1 modem be provisioned in?
IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).
How are 8-position, 8-connect (8P8C) modular connectors pinned to (UTP) cable, which is used for connecting computers and broadband modems to a local area network (LAN)?
Identical at opposite ends, or straight-through.
One of the first things a technician needs to address in troubleshooting issues with digital video quality is...
Identify the problem by asking the customer to describe the problem and whether or not it is intermittent or constant.
When troubleshooting a continuous dial tone problem, what is necessary to do?
Identify where the polarity of the telephone wiring is reversed.
Check the station wiring and connectors between the EMTA and the telephone outlets
If a customer has no dial tone (NDT) on any of their phones, but there is a dial tone directly from the embedded multimedia terminal adapter (EMTA), what should be done next?
Check if any cables are disconnected, make sure the TV set is properly configured, and check to see if the TV is on (if audio runs through a different system such as surround sound).
If a customer reports that a program's audio plays but there is no video display, the recommended actions are
The program is being played on a second set-top box in a whole house or multi-room digital video recording (DVR) configuration.
If a digital video service customer calls with an issue related to not being able to delete a recorded program, it could be caused by
Check the line of sight between the remote control and the set-top box.
If a digital video service customer reports that the set-top box does not respond to the remote control, what is the quickest and easiest thing to do first?
A digital signal analyzer to measure modulation error ratio (MER) and bit error rate (BER) before forward error correction (FEC).
If digital carrier quality is marginal, intermittent tiling will be a problem. What should be used to identify and troubleshoot this condition?
3 dB.
If there is a problem with one particular digital channel, adjacent channels should also be tested. A difference of more than how many decibels (dB) between adjacent digital channels can reduce the modulation error ratio (MER) performance of the channel with the lower signal level?
The poor quality of analog programming displayed on a digital TV set, a common complaint of customers, can be caused by...
Image rescaling that standard definition TV (SDTV) analog programs require to be displayed in a 1080p resolution display.
A root raised cosine filter.
In a quadrature amplitude modulation (QAM) signal, the faster the signal transition from one symbol to another, the higher the number of harmonics. In a QAM modulator, what is used to eliminate these harmonics and limit the occupied bandwidth of the channel?
0-0.8 volts.
In a transistor-transistor logic (TTL), each terminal is constantly, and instantaneously, in one of two voltage conditions. What is typically a low voltage state?
A critical step in troubleshooting is verifying the signal levels and signal quality at the tap to establish the baseline performance for the installation.
In addition to being accurate and detailed, a successful troubleshooter knows that
Transmitted once with data that tells the decoder where, on the single frame, the array is displayed.
In intraframe coding, data for redundant pixel arrays are
False.
In order to more easily discuss and design logic gates, high and low voltage states are designated by a few simple terms. Which of the following can be used to refer to a low voltage state?
Gray coding.
In quadrature amplitude modulation (QAM) bipolar coordinate graphs, all adjacent symbols are different by only one bit. What is this planned condition known as?
Telephone jacks and circuitry to send and receive telephone calls over the DOCSIS network.
In the DOCSIS HFC access network, an embedded multimedia terminal adapter (EMTA) includes
Internet protocol television (IPTV) and high-speed data (HSD).
In the broadband cable system, digital services can be grouped into two product categories; digital television (DTV) and Data Over Cable Service Interface Specification (DOCSIS®) products. Which of the following digital services fall under the DOCSIS product category?
Determine if the original outlet needs to be repaired.
In troubleshooting a digital-to-analog converter, try the suspect converter in a different, working outlet to
Are there similar complaints from other customers?
In working through a flowchart for the six-step process of troubleshooting a report of tiling by a single customer, one of the first questions asked should be
Coherent interference causes the constellation display to look like a series of small donuts. What is one cause of coherent interference?
In-channel ingress.
Some of the common causes of digital video impairments in a distribution network include...
Incorrect signal levels, common path distortion caused by corroded connections and impedance mismatches due to unterminated taps.
Which of the following describes why the HFC return path design is especially sensitive to ingress and noise?
Ingress and noise from multiple drops along a service area funnels into a common point, affecting all signals from that service area
An intra-coded frame to compare picture information between consecutive frames, using motion vectors, which results in predicted frames (P-frames).
Interframe coding, a form of temporal compression, uses
What will any short in the premises wiring or connected CPE do to telephone or HSD service in the premises network.
It will disable both services.
Inter-symbol interference (ISI).
Linear distortion of a received signal is defined as any characteristic change (frequency response, phase, tilt, bandwidth, etc.), other than amplitude, from the transmitted signal. On a digital carrier, what does linear distortion cause?
Decibel (dB) values to power and voltage units.
Logarithms and antilogarithms allow signals to be more easily added and subtracted together or have their amplitude and power multiplied and divided. What does an antilogarithm convert?
A customer reports a problem of no dial tone (NDT), Upon inspection, the technician notices that new carpeting has been installed. What should the technician do next?
Look for a cable that runs under the carpet; it is likely that the cable has a short from the carpeting tack strip.
The human eye cannot detect that the data is missing.
MPEG (Motion Picture Experts Group) digital video compression is called lossy because the data output at the decoder is not identical to the data originally input at the encoder. Which of the following explains why the lost data is not a problem?
Bidirectional coded frame (B-frame).
MPEG compression uses a series of data frames to allow moving pictures to be coded with a minimal amount of data. Which type of data frame contains the least amount of data?
On a MPEG-2 transport stream.
MPEG-4 advanced video coding (AVC) enables HDTV to be compressed more efficiently without a loss of quality. How must MPEG-4 AVC content be transported?
To save measurement time, some cable operators perform automated measurements on a sample of channels which can result in problems going undetected in unmeasured channels.
Many cable operators have a drop certification program and require measurements using a digital signal analyzer with minimum and maximum criteria programmed into the instrument. Why should the technician recognize and understand which channels are being measured when automated measurements are being performed by the digital signal analyzer?
Approximately seven to twelve.
Migrating cable operations to an all-digital platform replaces analog channels with digital channels. For every 6-megahertz (MHz) analog channel that can be replaced with a 256-QAM (quadrature amplitude modulation) digital carrier, how many additional standard channels can be added to the line-up?
= 32 dB.
Modulation error ratio (MER) is an indicator of digital modulation signal quality. For error-free reception and adequate margin, what should be the minimum MER reading for a 256-QAM (quadrature amplitude modulation) signal?
Which of the following devices have diagnostic pages which can be used to confirm and verify operation of the return path?
Most cable modems, embedded multimedia terminal adapters (EMTA), and STBs have diagnostic pages
Every microprocessor is an IC.
Most electronics used in a cable plant and cable system are designed with integrated circuits (IC). Which statement about the relationship between integrated circuits (IC) and microprocessors is true?
Enhanced TV Binary Exchange Format (EBIF).
New cable services are implemented based on cost and need. What is a subset of tru2way which will allow cable operators to give customers some of tru2way's function without all of its cost?
Impulse noise.
Noise is a generic term to describe unwanted energy in a system. What type of noise occurs from ingress and is characterized by large unpredictable noise bursts?
4.2 megahertz (MHz).
Nyquist-Shannon sampling theorem found that the ideal sampling rate for any analog signal was twice the highest frequency perceived by human eyes and ears. Therefore, where should sampling occur for National Television System Committee (NTSC) analog video?
what are two features that were added in the docsis 3.1 to extend the viability of HFC into the next decade?
OFDM and LDPC
Sends a dynamic host configuration protocol (DHCP) discovery message to the DHCP server.
Once a two-way connection is established, a Data Over Cable Service Interface Specification (DOCSIS®) modem needs additional information to attach to the Internet protocol (IP) network. Which of the following does the modem do when making an IP connection?
Both calling and receiving parties had to have computers that were turned on and running VocalTec software.
One obstacle to wide-spread adoption of early voice over Internet protocol (VoIP) applications was
Identify the problem by asking the customer to describe the problem and whether or not it is intermittent or constant.
One of the first things a technician needs to address in troubleshooting issues with digital video quality is
Verify the problem is resolved by taking measurements to confirm the resolution and ensuring the resolution did not introduce new problems.
One of the last things a technician does when following a process for troubleshooting and resolving problems with digital video quality is
What are two features that were added in DOCSIS 3.1 to extend the viability of hybrid fiber/coax (HFC) networks into the next decade?
Orthogonal frequency division multiplexing (OFDM) and low-density parity-check (LDPC).
The service quality from the PacketCable managed IP network.
PacketCable voice over Internet protocol (VoIP) is differentiated from VoIP service offered by other providers by
An objective measurement of human visual perception based on a statistical analysis of quality of service (QoS) measurements and MPEG encoding data.
Perceptual quality metrics (PQM) provide cable operators with
To create a circular pattern.
Phase noise is an indication of carrier frequency stability. What does phase noise cause the constellation symbol error clouds to do?
What information is provided from a Ping command?
Ping is used to measure the round-trip time for a ping packet to travel over the network form the cable modem to the (CMTS), or other server, and back.
The local loop.
Plain old telephone service (POTS) is the traditional telephone service that, until recently, was the only telephone service. Which of the following is the connection between the customer and the telephone company?
Decibels per milliwatt (dBm).
Power can be measured at a particular frequency, spread over a bandwidth, or equal the total power in a network. What measurement unit is used when expressing the power of a signal?
The peak power is 6- to 13-decibels (dB) greater than the channel's average power.
Power peaks occur randomly, adding to and subtracting from the average power of a quadrature amplitude modulation (QAM) channel. How does the peak power of a QAM channel compare to the channel's average power?
what was added to the first docsis that enabled a broadband cable operators to provide telephone service with quality and reliability that rivaled the products of the traditional telephone companies
QoS controls, enhanced security, and adaptive equalization in the upstream path
Ratio of time that a system or service is available for use to total time.
Quality of service (QoS), as measured by availability, describes the
B) A 55/70 split.
Radio frequency (RF) amplifier manufacturers build amplifiers with diplex filters designed to various forward and return frequency splits. Which of the following is a common frequency split sometimes used in other parts of the world?
Which type of signal impairment cause the constellation symbol points to spread out toward the grid lines?
Random noise.
The process of managing the data rates of multiplexed individual channels on a quadrature amplitude modulation (QAM) carrier.
Rate shaping, a possible point of failure for digital video in the headend, describes
Quality of service (QOS), as measured by availability, describes the...
Ratio of time that a system or service is available for use to total time.
Quality of service (QoS) metrics are important to help identify potential problems before they can affect a customer's more subjective quality of experience (QoE).
Regarding digital video quality at the customer premises,
How is silver satin cable used to connect telephone equipment to wall outlets typically pinned?
Reversed at opposite ends, or cross-pinned.
Which of the following describes the methods used to determine if a STB is non responsive?
STB are polled to see if they respond and a report is created, non-responsive STBs can result in a significant loss of revenue.
Digital set-top box diagnostics can aid a technician with which of the following parameters while troubleshooting?
Service authorization, received signal quality, and return path operation.
What should be checked as a possible cause of hum on a customer's telephone line?
Shielding problems in the station wiring, poor terminations, or poor grounding and bonding.
Incorrect signal levels, common path distortion caused by corroded connections, and impedance mismatches due to unterminated taps.
Some of the common causes of digital video impairments in a distribution network include
Rate-shaping.
Statistical multiplexing is not an error-free system. To account for the times when the bandwidth requirements of the statistically multiplexed programs exceed the bandwidth capacity of the system, what process is used?
A dynamic device with the capability of constantly mixing variable bit rate (VBR) programming.
Statistical multiplexing provides the most video services possible within a fixed bandwidth. Which of the following best describes a statistical multiplexer?
Which step in the troubleshooting process requires a discussion with the customer to gather more detail about the problem?
Step 1: Identify the problem.
Which Data Over Cable Service Interface Specification (DOCSIS) layer is used by the CMTS to differentiate between cable modems?
The DOCSIS Media Access Control (MAC) layer.
They are at the same frequency, 90 degrees out of phase with each other.
The I carrier is known as the in-phase carrier and the Q carrier is called the quadrature carrier. What is the relationship between these two carriers?
The storage and retrieval of DTV content.
The MPEG-2 bit stream provides a means to transport compressed digital television (DTV) data and reconstruct it for totally different applications. For what application is the MPEG-2 Program Stream designed?
MPEG-4.
The Motion Picture Experts Group (MPEG) develops standards for digital, compressed moving pictures, and associated audio. Which of the following MPEG standards targets digital television (DTV) applications over the Internet or in mobile devices?
During the modulation stage.
The North American quadrature amplitude modulation (QAM) standard specifies two additional layers of processing before and after modulation, MPEG-2 framing and forward error correction (FEC). Which is a function of the MPEG-2 framing layer?
In the telephone test set, placing the T/M switch in the TALK position establishes an off-hook condition for dialing and talking. What is an off-hook condition of a telephone?
The active, in use state of a telephone.
A loud click can be heard if the circuit is closed when troubleshooting which side of a fault?
The battery side of the fault.
Video capture and processing artifacts that cannot be addressed at the customer premises.
The digital artifacts referred to as blockiness, blurring, mosquito noise, and contour represent
The adaptive equalizer (AE) stage.
The digital receiver is designed to compensate and correct for reasonable levels of linear distortion and noise that are created in the cable network. Which stage measures and corrects linear distortions before the data goes to the forward error correction (FEC) stage?
The types of artifacts generally found at the customer premises due to timing delay and frame rate, respectively.
The digital video artifacts of loss of lip sync and smearing are associated with
To resolve where the source of a digital video problem lies, a technician uses...
The divide-and-conquer method for troubleshooting, which can begin with measurements on customer premise equipment that offer easier access for testing
The Reed-Solomon layer.
The forward error correction (FEC) process contains four processing layers. Which layer is a complex error correction scheme that divides the transport stream data packet into blocks of symbols?
Ensures the receiver can identify, lock, and synchronize its internal clock on the channel.
The modulation process for eight vestigial sideband (VSB) signals has a number of similarities with quadrature amplitude modulation (QAM). However, the 8-VSB modulation process distinguishes itself from the QAM modulation process by adding an Advanced Television System Committee (ATSC) pilot with sync information that does what?
What was done in DOCSIS 3.0 to allow enough bandwidth for upstream carriers from previous DOCSIS versions?
The option to increase the top frequency of the upstream to 85 MHz.
What is the difference between the wiring configurations for a residential, 8-position, 8-contact (8P8C) modular plug and jack in the Universal Service Order Codes (USOC) and ANSI/TIA/EIA 570-B?
The placement of pair numbers 3 and 4.
Image rescaling that standard definition TV (SDTV) analog programs require to be displayed on a 1080p resolution display.
The poor quality of analog programming displayed on a digital TV set, a common complaint of customers, can be caused by
Rate shaping, a possible point of failure for digital video in the headend, describes...
The process of managing the data rates of multiplexed individual channels on a quadrature amplitude modulation (QUM) carrier.
The quantizing process.
The pulse code modulation (PCM) process as it relates to digital television (DTV) consists of sampling, quantizing, and encoding. Which process allows for discerning subtle differences, thereby creating the impression of natural voice and imaging?
he National Telecommunications and Information Administration (NTIA).
The radio spectrum is the radio frequency (RF) portion of the electromagnetic spectrum. Which agency administers the federal use of spectrum to organizations such as the military, Federal Aviation Administration (FAA), and the FBI?
Between 5-42 megahertz (MHz).
The return spectrum is in ever-increasing demand as customers' desire to upload more data onto the cable system increases. What is the return path for most North American cable systems defined as?
The eye diagram.
The same integrated power measurement techniques used for quadrature amplitude modulation (QAM) and other digital signals are used for 8 vestigial sideband (VSB) signals. What 8-VSB measurement technique shows signal transitions as a signal vector moves from symbol to symbol?
It allows for viewing fast transient signals or noise, which is common on the return path.
The spectrum analyzer is the instrument of choice for measuring carrier level, noise, and ingress on the return path. What is the max hold or peak hold function on a spectrum analyzer used for?
When analyzing a problem, what can the technician learn by asking the customer to show or demonstrate the problem?
The symptoms of the problem can be viewed and any unusual screens or customer entries can be identified.
What could cause some dual tone multifrequency (DTMF) touch-tone telephones in the customer premises to have continuous dial tone caused by polarity reversal, but not other telephones?
The telephone wiring polarity is incorrect, and the customer has a mix of older and newer DTMF touch-tone telephones.
Tier I, primary line VoIP.
The tier that enables a cable operator to deliver VoIP service comparable in quality and reliability to POTS, by specifying and controlling the delivery of VoIP packets, is
Velocity of propagation (VOP).
The time between an incident signal and the tap can be used to identify the approximate location of a micro-reflection. The distance to each micro-reflection can be calculated by multiplying the tap time by the cable's what?
Pt = L+10Log10(N)
The total power in a system is an indication of all of the signals lumped together without regard to individual channel levels. What equation is used to calculate the total power of signals of equal amplitude?
What are some Advantages of using a twister-pair cable tester to troubleshoot telephone station wiring and UTP cable in the customer premises>
The twisted-pair cable tester is designed specifically to test and diagnose twisted-pair cable and its connections, as well as measuring data throughput while being fairly inexpensive and easy to use.
The digital video artifacts of loss of lip sync and smearing are associated with...
The type of artifacts generally found at the customer premises due to timing delay and frame rate, respectively.
The information-carrying capacity of a modulation or transport medium.
The way in which the term bandwidth is used determines its meaning. In the context of digital communications, what is bandwidth used to describe?
Sidebands and harmonics.
Theoretically, the required bandwidth for a quadrature amplitude modulation (QAM) channel is equal to the symbol rate. However, when a continuous wave (CW) carrier is amplitude modulated, what results from the modulation process?
Trellis coding.
There are four major forward error correction (FEC) layers: Reed-Solomon, interleaving, randomizing, and trellis coding. Which layer deals with the symbol-to-symbol transitions?
Run-length coding.
There are many methods of data compression, each designed to remove redundant data prior to its transmission. Which type of data compression is used by a fax machine?
D) The NOT gate
There are seven basic logic gates, each designed to follow a specific rule of Boolean logic. Which logic gate acts as an inverter by reversing the logical input state?
By allowing for increased data rates through the use of forward and return channel bonding
There are several methods that can be used to make existing bandwidth more efficient. How does the DOCSIS 3.0 specification increase the efficiency of existing bandwidth?
Modulation error ratio (MER).
There are three primary performance measurements of a digital carrier. Which measurement is a good indication as to where the average channel performance is with respect to the cliff effect?
To synchronize a decoder to real time.
There are two types of time stamps, the decode time stamp (DTS) and the presentation time stamp (PTS). What is a time stamp used for?
When a viewer receives a "channel not available, try again later" message, the probable cause is...
There is insufficient bandwidth from the headend to the hub to accommodate the data stream for the requested channel.
If the customer is an internet novice, what would be the benefit of saving your company's website as their home page?
They might appreciate having easy access to a website that contains links to their email and other useful or interesting links
Tiling, missing audio, and frozen picture are examples of artifacts that
Tiling, missing audio, and frozen picture are examples of artifacts that
The conditional access table (CAT).
To decode encrypted programming, a decoder must know where to access the entitlement management messages (EMM). Which of the following tables contains the EMM information?
Cable operators use a quality of experience (QoE) measurement based on mean opinion score (MOS) and perceptual quality metrics (PQM).
To determine if objective network data measured by quality of service (QoS) parameters match a customer's overall satisfaction level,
Check the set-top box (STB) and the television set to ensure audio connections have been made correctly.
To eliminate possible causes of audio issues, a technician can
The divide-and-conquer method for troubleshooting, which can begin with measurements on customer premise equipment that offer easier access for testing.
To resolve where the source of a digital video problem lies, a technician uses
Many cable operators have a drop certification program and require measurements using a digital signal analyzer with minimum and maximum criteria programmed into the instrument. Why should the technician recognize and understand which channels are being measured when automated measurements are being performed by the digital signal analyzer?
To save measurement time, some cable operators perform automated measurements on a sample of channels which can result in problems going undetected in unmeasured channels.
In intraframe coding, data for redundant pixel arrays are...
Transmitted once with data that tells the decoder where, on the single frame, the array is displayed.
The set-top box (STB).
Tru2way is a software platform that allows two-way communications between the cable operator and the home. What hardware does it eliminate the need for?
When a communications issue is suspected in an HDMI device, the technician should...
Try an alternate HDMI port on the device, if one is available.
How should the digital multimeter (DMM) be used to troubleshoot problems in the telephone wiring?
Use the voltmeter function; both the NID and the EMTA provide a steady on-hook voltage.
Minimal delay in exchange for less reliable delivery of data packets, and with no packet management overhead to guarantee and prioritize packet delivery.
Using UDP (user datagram protocol), VoIP packets travel through the network experiencing
Temporal compression.
Using algorithms to remove redundancy between video frames makes it possible to transport digital video on multiple mediums without a perceived loss of quality. What inter-coding process between video images uses motion compensation in the time axis to identify redundant information between video frames?
The decimal point is six places to the right of the one.
Using powers of 10 is a way to work with very small and very large numbers. In the base 10 number 106, what does the exponent value indicate?
Which of the following are among the reasons why a customer may not be able to order video-on-demand?
VOD or pay-per-view credit limits might have been reached, indicating that purchases have not been collected due to a return path problem.
After resolving the problem with the premises wiring issue, which of the following is the next step in the six-step process that the technician should take?
Verify that the problem has been resolved and that phone service is running perfectly on all phones.
One of the last things a technician does when following a process for troubleshooting and resolving problems with digital video quality is...
Verify the problem is resolved by taking measurements to confirm the resolution and ensuring the resolution did not introduce new problems.
The digital artifacts referred to as blockiness, blurring, mosquito noise, and contour represent...
Video capture and processing artifacts that cannot be addressed at the customer premises.
A) 10-decibels (dB) lower than analog.
Virtually all cable systems carry a combination of analog and digital channels, so standard practice is to operate the digital channels at lower average power levels than the analog channels. For 64-quadrature amplitude modulation (QAM) channels, what do most systems set their average power levels to?
Macroblocking.
Visual artifacts are a result of a quadrature amplitude modulated (QAM) downstream signal encountering noise and other radio frequency (RF) impairments. Which of the following is an artifact of overcompression?
IPv4 only, IPv6 only, alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).
What Internet protocol (IP) connectivity modes are supported in DOCSIS 3.0 and 3.1?
Latency, jitter, and calculated mean opinion score (MOS).
What Internet protocol (IP) voice parameters are provided by the IP voice analysis function of a signal level meter (SLM)?
Pulse code modulation (PCM), digital signal (DS) hierarchy, and the T-carrier trunk hierarchy.
What are some of the standards that came out of building the digital public switched telephone network (PSTN)?
The energy in a QAM carrier is distributed across the entire bandwidth of the carrier.
What characteristic of a quadrature amplitude modulation (QAM) carrier causes amplitude measurement inaccuracies on conventional spectrum analyzers and signal level meters (SLM)?
An orthogonal frequency division multiplexing (OFDM) channel that contains a set of contiguous subcarriers called the PHY link channel (PLC).
What does a DOCSIS 3.1 seek first when synchronizing with the cable modem termination system (CMTS) in order to receive operational information?
The EMTA recently ran off battery power and is currently being charged.
What does a flashing battery LED on an embedded multimedia terminal adapter (EMTA) indicate?
The Data Over Cable Service Interface Specification (DOCSIS) cable modem is acquiring the Internet (IP) addresses and configuration files.
What does it mean when the embedded multimedia termination adapter's (EMTA) ONLINE LED is flashing during registration?
The modem proceeds to an operational state and issues at least one ToD request per 5-minute period for each server specified until local time is established.
What happens if a DOCSIS modem is unable to acquire the current time and date from one or more time-of-day (ToD) servers during registration with the cable modem termination system (CMTS)?
How much the adaptive equalizer has to compensate for linear distortions of the digital carrier.
What information about the digital carrier can be learned by accessing the adaptive equalizer function of the digital signal analyzer?
The modem's downstream service group (DS-SG) if determined.
What information does a DOCSIS 3.1 modem provide in its Bonded Initial Ranging Request (B-INIT-RNG-REQ) message to the cable modem termination system (CMTS)?
Ping is used to measure the round-trip time for a ping packet to travel over the network from the cable modem to the cable modem termination system (CMTS), or other server, and back.
What information is provided from a Ping command?
An adjustment to the modem's timing interval, transmit frequency, or power level.
What instructions might a cable modem termination system (CMTS) send in a RNG-RSP message to modify the modem's transmission parameters?
Tighten all RF connectors and terminate unused outlets, as this will prevent noise or ingress from intermittently entering the return path.
What is a possible solution for a customer having intermittent one-way telephone calls?
When the cable modem termination system (CMTS) receives a registration acknowledge (REG-ACK) message confirming the modem's registration
What is the last step in a cable modem's registration?
There is either no Data Over Cable Service Interface Specification (DOCSIS) carrier or the DOCSIS carrier is not being recognized by the EMTA.
What is the likely problem if the DS indicator on an embedded multimedia terminal adapter (EMTA) flashes continuously and never progresses to another stage?
A bonding block.
What kind of primary protection is recommended to protect the coax within 50 feet of its entrance to a building?
The bit error rate (BER) measurement before forward error correction (FEC).
What measurement is a true indication of a system's quality and can be used to determine how close a system is to failure?
An upstream channel descriptor (UCD) message, a symbol timing message (SYNC), and a bandwidth allocation message (MAP).
What messages must a cable modem receive from the downstream signal in order to begin a transmitting relationship with the cable modem termination system (CMTS)?
A signal level meter (SLM) with digital signal analyzer, cable modem analyzer, and IP voice analysis functions.
What piece of test equipment is most suitable for diagnosing embedded multimedia terminal adapter (EMTA) operation?
Call the service center and make sure that the EMTA's media access control (MAC) address matches the address in the operator's database.
What should the technician do if the main telephone port on the embedded multimedia terminal adapter (EMTA) has a failure due to faulty provisioning?
It prevents a cloned modem from full, illegal, access to the network.
What type of security does the baseline privacy interface (BPI) protocol provide?
Try an alternate HDMI port on the device, if one is available
When a communications issue is suspected in a an High-Definition Multimedia Interface (HDMI) device, the technician should
There is insufficient bandwidth from the headend to the hub to accommodate the data stream for the requested channel.
When a viewer receives a "Channel not available, try again later" message, the probable cause is
When the ONLINE indicator is illuminated, which is after the modem side of the EMTA receives its IP addresses and configuration files from servers in the headend.
When do the telephone ports on the embedded multimedia terminal adapter (EMTA) receive their Internet protocol (IP) addresses and configuration files?
When equipment is connected via the component video output,
When equipment is connected via the component video output,
Carrier level, bandwidth, and system noise.
When modifying the application of a digital receiver to that of a test instrument, the quadrature amplitude modulation (QAM) analyzer is very practical. Most QAM analyzers include a spectrum analyzer to enable analog measurement of what?
Talk to the customer and ask what they are experiencing and listen carefully to their answer.
When troubleshooting a telephone service problem in the customer premises, what is the best way to identify the problem?
5.360537 megasymbols per second (MS/s).
When you use a digital signal analyzer to examine a digital signal, one of the values you should check is the symbol rate. What should the symbol rate setting be for a 256-QAM signal specified by the International Telecommunication Union (ITU) in ITU-T J.83 Annex B?
VOD or pay-per-view (PPV) credit limits might have been reached, indicating that purchases have not been collected due to a return path problem.
Which of the following are among the reasons why a customer may not be able to order video-on-demand (VOD)?
IPV4 addressing
Which of the following is a feature of DOCSIS 2.0?
Multimedia over Coax Alliance (MoCA).
Which set of standards allows television sets, set-top boxes (STB), and DVRs in the home to share digital video content with one another?
Random noise.
Which type of signal impairment causes the constellation symbol points to spread out toward the grid lines?
Every time the cable modem analyzer function is enabled, the instrument's internal modem must be provisioned with the cable modem termination system (CMTS).
Why does it take a few minutes for a cable modem analyzer to become functional once connected to the network?
Packet-switching operates over a shared network and occupies the network only for the duration of time it takes to transport the data packet.
Why is packet-switching technology considered to be more efficient than circuit switching technology?
To enable the cable operator to define special modem classes or service levels that can be prioritized for ranging after a massive outage.
Why would a cable operator consider activating device class identification (DCI) as part of a DOCSIS modem's initialization?
An Ethernet cable is connected from the cable modem analyzer to the customer's computer, and the RF drop input cable is connected to the cable modem analyzer.
You have a cable modem analyzer and you want to replace the cable modem to determine whether the modem is bad. How should the modem analyzer be connected to replace the modem?
Which of the following devices I the best choice when trying to isolate the cause of cable telephony or high speed data cable modem performance problems?
a return path tester can be used to easily isolate the cause of cable telephony or HSD cable modem problems in the drop system
When aligning the return amplifiers which method will deliver the most accurate alignment results?
a return sweep from 5-42 MHz will deliver the most accurate alignment results
it is essential to pay attention to warning signs of stress overload, poor attitude is one of the behaviors that may indicate that you are overstressed, what are symptoms of poor attitude behavior?
a significant change in attitude with a noticeable movement toward negative, hostile, cynical, or paranoid thoughts
if the drop loss at the ground block is 3.2 db and is connected to a three way splitters hot leg and then connected to the 9 Db leg of a directional coupler what will be the total return loss
add them together for the total return
what could result if a customer's network has a data throughput of 6 megabits per second and three different tvs streaming at 12 Mbs each
all three HDTVs will experience glitches, annoying visual artifacts, or buffering
. how can you use the five Ws technique for note taking when troubleshooting a problem?
ask questions that begin with who, what, when, where, and why? Write down the answers to help in your analysis of the problem
Where in the outside plant return path is one of the largest funnel points of RF return signals in the network?
at the node
Which of the following describes the primary source of attenuation in the return path?
attenuation in the return path is primarily due to the coax cable
why are the data throughput rates for both downstream and upstream in docsis networks asymmetrical?
because the narrower bandwidths and lower orders of modulation for the return path carries cause the docsis downstream and upstream data rates to be unequal or aysmmetrical
Some cable operators charge an additional fee when the amount of downloaded data during a billing cycle exceeds a prescribed limit. How might a customer unknowingly approach these limits?
by streaming/downloading high content data i.e movies, tv shows in high definition
What criteria does the docsis certification process ensure?
compliance with the docsis standard and interchangeability between suppliers
what is the trend that desktop computers are moving toward in many homes?
desktop computers are moving toward being used as a home network server
what docsis specification was the first to provide an option for raising the top frequency of the upstream spectrum to 85 mhz in order to create enough bandwidth for upstream carries from modems running on previous versions?
docsis 3.0
The zero span and max hold features of a spectrum analyzer allow accurate measurement of which of the following impairments?
fast transient signals such as impulse noise
from where do docsis modems receive their configuration files, billing system messages, and access control messages?
from the CMTS acting as a proxy or messenger that transferes messages and files between the modems and the respective servers
which of the following is a method for controlling expectations?
identify the source of emotional overload
.you are at a customer's home and you are asking the customer whether the program is intermittent or constant. Which step are you using from the six step troubleshooting process?
identifying the problem
which of the following procedures will reduce impulse noise?
impulse noise can be reduced by tightening all connections and installing 75 ohm terminators on all unused tap ports
what is a common solution to signal reflections where tap values are less than 17 db?
installing high pass filters on all unused tap ports
if a customer already has television service and is adding high speed data service, what should be checked on the digital television channels?
intermittent operation, which is a symptom of noise interference in the downstream
the first version of docsis was approved as an international standard by what organization?
international telecommunication union (ITU)
what internet protocol addresses modes can a docsis 3.0 and 3.1 modem be provisioned in?
ipv4, ipv6, apm, and dpm
what layers of the OSI model are applied between docsis and the CMTS
layers 1-4, physical, data link, network, and transport
which of the following describes long loop automatic gain control?
long loop AGC adjusts the transmit levels of the customer premise equipment
what are some possible causes of signal reflections?
loose or bad connections in the drop system and un-terminated tap ports, especially on low value taps
.by taking control of the expectations you have, you are
more likely to improve your motivation and be a better problem solver
which of the following describes the typical sub band return frequency design for a cable modem?
most cable modems are designed to operate above 28 and below 38 mhz
in the docsis network, why is the data throughput over the return path typically less then the forward or downstream?
narrower bandwidths and lower orders of modulation
what does a home network printer have that enables it to operate through a network connection?
network interface card
Where should the customer be encouraged to go for information and questions before calling in?
online, to the website, FAQ page
what is the role of the router in the home media network
operating between the modem and the rest of the network, the router assigns internet protocol ip address to all of the network elements, then uses the ip addresses to direct traffic among network elements
what features were introduced with docsis 3.1 to increase the downstream and upstream data throughput?
orthogonal frequency division multiplexing (OFDM) and low density parity check (LDPC)
which OSI modem layers does the MAC layer in the docsis overlap?
physical and data link layers
which of the following best describes stereotyped thinking?
presuming that all members of a group have certain characteristics
a network attached storage NAs element should be connected to what element in the home media network?
router
What device can be installed with a cable modem to enable internet access to two or more devices in the customer premises?
router with a built in multi ethernet switch
Which of the following methods is employed to reduce traffic congestion on a HFC network?
splitting the distribution legs into separate optical return paths
which step in the troubleshooting process requires a discussion with the customer to gather more detail about the problem?
step 1-identify the problem
what entertainment multimedia elements are capable of receiving and converting streamed over the top media into television format?
streaming media players, many blu ray disc players, gaming consoles, and smart tv
when analyzing a problem, what can the technician learn by asking the customer to show or demonstrate the problem?
symptoms of the problem can be viewed and any unusual screens or customer entries can be identified
to break the habit of a negative self-talk cycle
tell yourself not now and move onto a positive thought whenever negative ones occur
the most common source of ingress and egress is located at which of the following points in the broadband cable network?
the customer premise and the drop cable
What is the definition of a home media network?
the home media network is defined as a collection of computer and media devices connected together on a single network
which docsis layer is used by the cmts to differentiate between cable modems?
the mac layer
If a digital video service customer calls with an issue related to not being able to delete a recorded program, it could be caused by...
the program is being played on a second set-top-box on a whole house or multi-room digital video recording (DVR) configuration.
Broadband cable operators view tv everwhere as the answer to what competitive service?
the streaming of media, television programs, movies, music, into data packets that can be received over the internet or OTT
Which of the following device applications can be used in a system to reduce ingress noise?
the use of a high pass filter at the tap will block any noise generated on the drop in the return frequencies from entering the leg.
Which of the following describes thermal noise?
thermal noise is caused by fluctuations in electron density within amplifier circuitry. As the signal passes through an amplifier, thermal noise is generated and added to the amplified signal.
what access technology does the first version of docsis 1.0 use to send data upstream over the networks RF return path?
time division multiple access (TDMA)
Why is it good practice to review the service work order with the customer before beginning a high speed data service installation?
to verify account information and to confirm the high speed data order
you are at a customer's home and you believe you have solved the problem, when do you check to be sure the resolution did not introduce any new problems which step are you using from the six step process?
verifying the solution
which of the following mitigation devices provide filtering on sub split return frequencies as described?
window filters act on specific frequencies from 5-42 Mhz
Installing a cable modem and router in a closet or utility room is simplified by having what items in the room?
working computer, platform for modem and router, twisted pair network cable with standard configurations
When helping a new customer set up email for the first time, what suggestion should you make regarding the customers login and password?
write it down and keep it in a safe place
