test #1
What piece of test equipment is most suitable for diagnosing embedded multimedia terminal adapter (EMTA) operation?
What piece of test equipment is most suitable for diagnosing embedded multimedia terminal adapter (EMTA) operation?
When troubleshooting a continuous dial tone problem, what is it necessary to do?
B) Identify where the polarity of the telephone wiring is reversed.
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?
C) A transposition.
Which of the following are among the reasons why a customer may not be able to order video-on-demand (VOD)?
C) 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 type of signal impairment causes the constellation symbol points to spread out toward the grid lines?
B) Random noise.
Quality of service (QoS), as measured by availability, describes the
B) Ratio of time that a system or service is available for use to total time.
Coherent interference causes the constellation display to look like a series of small donuts. What is one cause of coherent interference?
A) In-channel ingress.
The digital video artifacts of loss of lip sync and smearing are associated with
A) The types of artifacts generally found at the customer premises due to timing delay and frame rate, respectively.
Which Data Over Cable Service Interface Specification (DOCSIS) layer is used by the cable modem termination system (CMTS) to differentiate between cable modems?
B) The DOCSIS Media Access Control (MAC) layer
When equipment is connected via the component video output,
C) Format settings for vertical resolution, scan method, and aspect ratio may need to be adjusted manually.
To resolve where the source of a digital video problem lies, a technician uses
C) The divide-and-conquer method for troubleshooting, which can begin with measurements on customer premise equipment that offer easier access for testing.
What would be the downstream throughput if two 256-QAM channels with a throughput of 38 megabits per second (Mbps) were bonded?
D) 76 Mbps.
What should be checked as a possible cause of hum on a customer's telephone line?
D) Shielding problems in the station wiring, poor terminations, or poor grounding and bonding connections.
What does a flashing battery LED on an embedded multimedia terminal adapter (EMTA) indicate?
D) The EMTA recently ran off battery power and is currently being charged.
Telephone test sets can be used to troubleshoot and locate open and short circuits. To locate a short circuit, open one side of the telephone line at any location and place the telephone test set in the loop—one lead connected to each side of the opened line. A loud click can be heard if the circuit is closed when troubleshooting which side of a fault?
D) The battery side of a fault.
What was done in Data Over Cable Service Interface Specification (DOCSIS) 3.0 to allow enough bandwidth for upstream carriers from previous DOCSIS versions?
D) 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?
D) The placement of pair numbers 3 and 4.
What is a possible solution for a customer having intermittent one-way telephone calls?
D) Tighten all RF connectors and terminate unused outlets, as this will prevent noise or ingress from intermittently entering the return path.
What is a predominant application for a wiremapper?
D) To certify the structured wiring in commercial buildings.
One of the last things a technician does when following a process for troubleshooting and resolving problems with digital video quality is
D) Verify the problem is resolved by taking measurements to confirm the resolution and ensuring the resolution did not introduce new problems.
In troubleshooting a digital-to-analog converter, try the suspect converter in a different, working outlet to
B) Determine if the original outlet needs to be repaired.
How is silver satin cable used to connect telephone equipment to wall outlets typically pinned?
D) Reversed at opposite ends, or cross-pinned.
Which step in the troubleshooting process requires a discussion with the customer to gather more detail about the problem?
B) Step 1: Identify the problem.
The poor quality of analog programming displayed on a digital TV set, a common complaint of customers, can be caused by
D) Image rescaling that standard definition TV (SDTV) analog programs require to be displayed on a 1080p resolution display.
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?
A) <1.0E-9.
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?
B) 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
B) Transmitted once with data that tells the decoder where, on the single frame, the array is displayed.
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?
C) Verify that the problem has been resolved and that phone service is running perfectly on all phones.
When using a digital signal analyzer to troubleshoot data throughput in the Data Over Cable Service Interface Specification (DOCSIS) network, what is the minimum modulation error ratio (MER) into the cable modem for a 256-QAM carrier?
D) 32 dB or greater.
When a viewer receives a "Channel not available, try again later" message, the probable cause is
D) There is insufficient bandwidth from the headend to the hub to accommodate the data stream for the requested channel
When do the telephone ports on the embedded multimedia terminal adapter (EMTA) receive their Internet protocol (IP) addresses and configuration files?
D) 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.
Describe the difference between a "short" and a "cross" in unshielded twisted-pair (UTP) cable.
A) 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.
When a communications issue is suspected in an HDMI device, the technician should
A) Try an alternate HDMI port on the device, if one is available.
You are using a 77HP tone generator in the Off/Polarity position to test a telephone line for voltage and polarity. You read the light emitting diode (LED) color to interpret the line status and the polarity and notice that the LED is bright green. What does a bright green LED indicate when testing a telephone line for voltage and polarity?
C) A clear working line with correct polarity.
What is the likely problem if the DS indicator on an embedded multimedia terminal adapter (EMTA) flashes continuously and never progresses to another stage?
C) There is either no DOCSIS carrier or the DOCSIS carrier is not being recognized by the EMTA.
What information is provided from a Ping command?
B) 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.
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?
C) Check the line of sight between the remote control and the set-top box.
Before using a twisted-pair cable tester it is a good idea to know which wiring scheme was used at the time the connectors were installed. If eight-pin connectors were used, what is the difference between the Universal Service Order Codes (USOC) wiring configuration and the T568A wiring configuration?
B) The configuration of pairs 3 and 4 are completely different.
Digital set-top box diagnostics can aid a technician with which of the following parameters while troubleshooting?
A) Service authorization, received signal quality, and return path operations.
When troubleshooting a telephone service problem in the customer premises, what is the best way to identify the problem?
A) Talk to the customer and ask what they are experiencing and listen carefully to their answer.
What does it mean when the embedded multimedia termination adapter's (EMTA) ONLINE LED is flashing during registration?
A) The DOCSIS cable modem is acquiring the IP addresses and configuration files.
In the telephone test set, placing the T/M switch in the "T" (talk) position establishes an off-hook condition for dialing and talking. What is an off-hook condition of a telephone?
A) The active, in use, state of a telephone.
What are some advantages of using a twisted-pair cable tester to troubleshoot telephone station wiring and unshielded twisted-pair (UTP) cable in the customer premises?
A) The twisted-pair cable tester is designed specifically to test twisted-pair cable continuity and its connections, as well as identify and diagnose wiring errors.
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?
B) = 32 dB.
A logical progression of events for resolving a customer's report of digital video artifacts on various channels could include
C) Analyzing the problem further to get a more narrow definition of the issue before trying to diagnose the symptoms of the problem.
If a customer reports that a program's audio plays but there is no video display, the recommended actions are
C) 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).
What will any short in the premises wiring or connected customer premises equipment (CPE) do to telephone or high-speed data (HSD) service in the premises network?
C) It will disable both services.
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?
C) Look for a cable that runs under the carpet; it is likely that the cable has a short from the carpeting tack strip.
The first step in testing wiring configurations is to determine which configuration you are testing. When testing the Universal Service Order Codes (USOC) wiring configuration, which of the following pairs is the default pair that is ready to test?
C) Pair 1 (pins 4 and 5).
Some of the common causes of digital video impairments in a distribution network include
D) Incorrect signal levels, common path distortion caused by corroded connections, and impedance mismatches due to unterminated taps.
What are two features that were added in Data Over Cable Service Interface Specification (DOCSIS) 3.1 to extend the viability of hybrid fiber/coax (HFC) networks into the next decade?
D) Orthogonal frequency division multiplexing (OFDM) and low-density parity-check (LDPC).
Regarding digital video quality at the customer premises,
D) 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).
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?
D) The telephone wiring polarity is incorrect, and the customer has a mix of older and newer DTMF touch-tone telephones.
Although off-network programming is not the responsibility of a cable operator,
A) 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) A three-bedroom house: The master bedroom telephone jack is connected directly to an embedded multimedia terminal adapter (EMTA), and bedrooms two and three are fed from the master bedroom telephone jack.
How does Internet protocol (IP) multicast differ from IP broadcast?
A) 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 Data Over Cable Service Interface Specification (DOCSIS) 3.0 and 3.1 modem be provisioned in?
A) IP version 4 (IPv4), IP version 6 (IPv6), alternate provisioning mode (APM), and dual-stack provisioning mode (DPM).
How are 8-position, 8-contact (8P8C) modular connectors pinned to unshielded twisted-pair (UTP) cable, which is used for connecting computers and broadband modems to a local area network (LAN)?
A) Identical at opposite ends, or straight-through
The indicators on a twisted-pair cable tester include pass, reversal, open, short, miswire, and split pair. What does a pass status indicate?
C) Pass indicates that the twisted-pair cable connections are "pinned" for straight-through wiring and the connection is electrically continuous without open or short circuit conditions.
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
C) The program is being played on a second set-top box in a whole house or multi-room digital video recording (DVR) configuration.
When using an inductive amplifier probe to identify a pair of wires, what is the purpose of shorting the leads of a tone-carrying pair?
C) The short cancels the induced tone on the pair of wires, thus the correct pair is identified when the tone disappears.
Tiling, missing audio, and frozen picture are examples of artifacts that
A) Are likely under the control of the technician in the hybrid fiber/coax (HFC) network or at the customer premises.
To determine if objective network data measured by quality of service (QoS) parameters match a customer's overall satisfaction level,
B) Cable operators use a quality of experience (QoE) measurement based on mean opinion score (MOS) and perceptual quality metrics (PQM).
What should the technician do if the main telephone port on the embedded multimedia terminal adapter (EMTA) has a failure due to faulty provisioning?
B) Call the service center and make sure that the EMTA's media access control (MAC) address matches the address in the operator's database.
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?
B) Check the station wiring and connectors between the EMTA and the telephone outlets.
The digital artifacts referred to as blockiness, blurring, mosquito noise, and contour represent
B) Digital video artifacts originating in the cable distribution network, which may be resolved by replacing faulty coax.
The telephone wiring is in the bus topology and the twisted-pair cable tester is connected at the embedded multimedia terminal adapter (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?
A) 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.
When troubleshooting telephone service in the customer premises, what is the next step if there is no dial-tone voltage at the telephone outlet?
A) 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.
To eliminate possible causes of audio issues, a technician can
A) Check the set-top box (STB) and the television set to ensure audio connections have been made correctly.
What information about the digital carrier can be learned by accessing the adaptive equalizer function of the digital signal analyzer?
A) How much the adaptive equalizer has to compensate for linear distortions of the digital carrier.
In addition to being accurate and detailed, a successful troubleshooter knows that
B) A critical step in troubleshooting is verifying the signal levels and signal quality at the tap to establish the baseline performance for the installation.
Perceptual quality metrics (PQM) provide cable operators with
B) An objective measurement of human visual perception based on a statistical analysis of quality of service (QoS) measurements and MPEG encoding data.
What IP voice parameters are provided by the IP voice analysis function of a signal level meter (SLM)?
A) Latency, jitter, and calculated mean opinion score (MOS).
Interframe coding, a form of temporal compression, uses
A) An intra-coded frame to compare picture information between consecutive frames, using motion vectors, which results in predicted frames (P-frames).
What is a limitation of using the shorted modular plug for testing the wiring of a modular connector?
B) 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.
One of the first things a technician needs to address in troubleshooting issues with digital video quality is
B) Identify the problem by asking the customer to describe the problem and whether or not it is intermittent or constant.
Rate shaping, a possible point of failure for digital video in the headend, describes
B) The process of managing the data rates of multiplexed individual channels on a quadrature amplitude modulation (QAM) carrier.
To perform a wire identification test, connect the test leads of a 77HP tone generator into a modular jack and press the On/Off button to activate the 200EP inductive amplifier probe. Use the 200EP to locate a tone signal at any point along a cable, distribution device, or at a modular telephone jack. How is the wire identification confirmed when using the inductive amplifier probe?
C) By touching the tip of the inductive amplifier probe to the signal-carrying conductor.
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?
D) 5.360537 megasymbols per second (MS/s).
Chrominance subsampling, which usually takes place in the studio environment, is the process of
D) 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.
What must be done before using a twisted-pair cable tester to diagnose unshielded twisted-pair (UTP) cable wired in the star topology inside the customer premises?
D) Disconnect all customer premises equipment (CPE) from all the jacks in the customer premises.
Why does it take a few minutes for a cable modem analyzer to become functional once connected to the network?
D) Every time the cable modem analyzer function is enabled, the instrument's internal modem must be provisioned with the cable modem termination system (CMTS).
When can the T568A wiring configuration, recommended in ANSI/TIA/EIA 570-B, be used for installing 8-position, 8-contact (8P8C) modular plugs and jacks for residential telephone service?
D) For telephone only installations that do not include data connections.
When analyzing a problem, what can the technician learn by asking the customer to show or demonstrate the problem?
C) The symptoms of the problem can be viewed and any unusual screens or customer entries can be identified.
How should the digital multimeter (DMM) be used to troubleshoot problems in the telephone wiring?
C) Use the voltmeter function; both the network interface device (NID) and the embedded multimedia terminal adapter (EMTA) provide a steady on-hook voltage.
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?
D) A short caused by a break in a conductor, poor contact in a modular connector, or an incorrect wire connection.
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?
D) 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.
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
D) Are there similar complaints from other customers?
In a Data Over Cable Service Interface Specification (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?
D) 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.
The Progressive Electronics 468 modular cable tester can be used to test a modular cable and its male plugs for faults. The condition and sequence order of the light emitting diodes (LED) on both the Progressive Electronics 468T (transmitter) and 468R (receiver) will indicate the test results. Which of the following test results is indicated by the green LEDs on both the 468T and 468R when they are sequencing out of order?
A) A transposed-pair test result.
