Digital Technician
What is a characteristic of the most common audio compression formats?
The most common audio compression formats are all lossy compression schemes with algorithms for discarding audio data with minimal perceived loss of quality by the listener.
From what is a sine wave created?
A sine wave is created from the values of sine through a full counterclockwise rotation at 0, 45, 90, 135,180, 225, 270, 315, and 360 degrees plotted on a graph.
Which compressed digital audio format is commonly found in movie soundtracks and used in consumer home theater system for its ability to handle surround sound formats?
AC-3.
How does using content delivery networks (CDN) to deliver streaming content from virtual multichannel video programming distributors (vMVPD) improve the viewing experience?
By shortening the distance between customers with their client devices and the servers that stream the content.
What type of noise is caused by the movement of electrons present in every component, system, and measuring instrument?
Random noise, properly called additive white Gaussian noise (AWGN), is caused by the movement of electrons present in every component, system, and measuring instrument.
What is Huffman coding based upon?
Huffman coding is a form of lossless compression that is based on certain characters or combinations of characters appearing in text more frequently than others.
Which of the following is true about Internetprotocol TV (IPTV)? Choose all that apply.
IPTV enables telephone companies to offer as many or more TV channels than a broadband cable operator. With IPTV the only channels transported on the network are those selected by customers from a server in the headend.
In a statistical multiplexer (statmux), what adjusts the channel flow through the buffers to prevent simultaneous peak bit rates of the channels in the multiplex?
Rate shaping algorithms.
Multicast distribution is preferred for what type of TV content?
Scheduled programs or live events that begin at specific times with the potential for millions of simultaneous viewers.
What does the transmission control protocol (TCP) add to the headers of each segment that are used by the receiving host to reassemble the segments in the correct order?
Sequence numbers.
Error vector magnitude (EVM)
Presented as a linear percentage calculation of average error over peak signal magnitude.
The Moving Pictures Expert Group (MPEG) defines transport stream composition in the MPEG-2 Transport Stream (MPEG-2 TS) specification. What is periodically inserted in an MPEG-2 TS to tell the decoder which packet identifiers (PID) are associated to reconstruct a program??
Program specific information (PSI).
What type of compression discards redundant data between frames while keep the changed data intact?
Temporal compression.
What is a common file extension for an MPEG-2 Program Stream (MPEG-2 PS) of digital TV (DTV) content that is stored in a computer file container?
The .VOB extension (for video object) is a common file container for a MPEG-2 PS for DTV content that is stored in a computer file container.
How many characters does the American Standard Code for Information Interchange (ASCII) 7-bit binary data code differentiate?
The general-purpose ASCII 7-bit binary data code differentiates 128 different characters.
How is a digital receiver able to detect and correct errHow is a digital receiver able to detect and correct errors in the payload that occur during transport?
The digital receiver uses forward error correction (FEC) data to detect and correct errors in the payload that occur during transport.
What position in the American Standard Code for Information Interchange (ASCII) character string is a single parity bit added?
The eighth-bit position to become the most significant bit (MSB).
Which logic gate acts as a logical either/or operator followed by a NOT gate?
The exclusive-NOR (XNOR) gate.
Which logic gate combines different logic gates to act as a logical either/or operator?
The exclusive-OR (XOR) gate.
What delays reception of data transported using the transmission control protocol (TCP)?
The extra data being sent for sequencing of segments by TCP creates overhead, that, along with acknowledgements of reception, delays the reception of data
Why does a television camera capture more light information, known as luminance, than color information, known as chrominance?
The mathematics and physics of a television camera attempt to duplicate the eye's physiology by capturing more light information, known as luminance, than color information, known as chrominance.
What happens when two channels of equal power, but different frequencies, are combined for transport over a network?
The total power of the combined channels is 3 dB over that of either channel.
What must a technician know to effectively use any test instrument?
To effectively use any test instrument, the technician needs to know what information the instrument is providing and recognize acceptable and unacceptable measurements.
Why does each Moving Picture Experts Group (MPEG)-2 group of pictures (GOP), begin with an Intra-coded frame (I-frame)?
To enable the decoder to reconstruct a video received in mid-stream, and a place where the video can be edited or a commercial inserted.
Why is randomizing included in the forward error correction (FEC) process?
To help the receiver maintain synchronization with the modulator.
Why is it common practice to set the average amplitude of digital modulation channels 6 to 10 dB below the maximum specified into the laser?
To reduce noise that accompanies the channel.
What is the purpose of the forward error correction (FEC) interleaving layer?
To reduce the probability of an impairment event corrupting more than one bit in a string.
When a test instrument indicates measurements that fall outside of minimum or maximum requirements, why should a technician recognize what the failed measurements are?
To troubleshoot and resolve the cause of failed measurements.
What type of Moving Picture Experts Group (MPEG)-2 data contains all the information necessary to reconstruct a single image?
intra-coded frame (I-frame) data.
What does a hole in the center of the quadrature amplitude modulation (QAM) constellation symbol error cloud indicate?
short term phase fluctuations in an oscillator creating noise sidebands on both sides of the oscillator signal
What is the decimal range of an 8-bit binary number?
0 - 255
What is the binary equivalent of decimal number 47?
00101111
What is the binary equivalent of decimal number 65?
01000001
High-dynamic range (HDR) video calls for a minimum color depth of 10-bits, which provides up to how many shades of each color?
1,024
What is the binary equivalent of decimal number 140?
10001100
For decimal number 210, what is the binary number?
11010010
For quadrature phase shift keying (QPSK), how many bits are in each symbol?
2 bits
Which generation of wireless access technology is operation in the millimeter frequency band around 30 GHz being considered?
5G
Which is the only 802.11 series of standards that operate at 900 MHz for reliable, slower-throughput connectivity with Internet of Things (IoT) sensors in the customer's home?
802.11ah
How many base-10 numbers can be expressed with two digits?
99
In a Moving Pictures Expert Group Transport Stream (MPEG-TS), what is used to synchronize the decoder video and audio to real-time?
A 27 MHz master clock, the program clock reference (PCR).
What feature of digital TV (DTV) technology did cable operators use until there was demand for high definition TV (HDTV) services?
A feature of DTV technology, video compression enabled broadband cable operators to transport up 12 TV channels in the 6 MHz frequency spectrum of a single analog TV channel until there would be demand for HDTV services.
When defined by the standards bodies, Internet protocol television (IPTV) was intended to have the same look and feel as TV delivered over what network medium?
A hybrid fiber/coax (HFC) network.
Other than presenting the customer with options for viewing multiple channels, what does broadcast distribution of channels over a broadband cable network favor?
A linear schedule of content that customers passively accept.
Forward error correction (FEC)
A mechanism for correcting data at the receiver that gets lost or corrupted during transport.
Which of the following best describes the Open Systems Interconnection (OSI) reference model?
A model that organizes the processes of network communications functions and services by network hardware and software into one of seven categories called layers.
For communications, what is required of the receiver?
A peer function or protocol that reverses the processing functions or protocols to send a signal.
What do all signal level measuring test instruments have through which the instrument sees the energy to be measured?
A resolution bandwidth (RBW) filter.
Micro-reflection
A time delay relative to the incident signal of a few microseconds (µs) or less.
Voice activated personal assistants are always listening for commands, but are programmed to respond only when hearing what? A wake word, such as the assistant's name.
A wake word, such as the assistant's name.
What is the data rate capacity of the eight-level vestigial sideband (8-VSB) RF/Transmission system defined by the Advanced Television Systems Committer (ATSC) for terrestrial digital TV (DTV) broadcasts?
ATSC A/53 Part 2 defines 8-VSB as the RF/Transmission system for terrestrial DTV broadcasts, delivering data rates up to 19.39 megabits per second (Mbps) in a 6-MHz television channel.
What opportunities are there for broadband cable operators that convert frequency spectrum previously used for analog modulation channels to digital modulation channels?
Additional revenue by adding new services or upgrading existing services.
Which compressed digital audio format aligns with the Moving Picture Experts Group (MPEG)-2 specification using more advanced compression algorithms for smaller sized files with better audio playback quality than its predecessor?
Advanced Audio Coding (AAC).
ICFR
Another way to observe how micro-reflections impact a QAM channel.
What type of applications are error vector magnitude (EVM) expressions best suited?
Applications that have small random noise-like errors.
How is the spectral density of a digital modulation channel expressed?
As decibels per millivolt per hertz (dBmV/Hz).
What process within audio PCM encoders accommodates the human ear's nonlinear sensitivity to sound level changes at low and high levels?
Audio PCM encoders use logarithmic companding to support the increased sensitivity of the ear to low levels while allowing enough dynamic range to encode high amplitude levels.
How is the five-layer Internet protocol (IP) suite formed?
By breaking the Network Access Layer from the four-layer IP suite into the Data Link Layer and the Physical Layer.
How is the perception of three-dimensional high definition TV (3D HDTV) created?
By displaying an image from two slightly different angles, like a pair of human eyes.
Why must the channel bandwidth be considered when calculating the total power going into return path lasers?
Because channel power is proportional to the bandwidth of the channel, the channel bandwidth must be considered when calculating the total power going into return path lasers.
Why is a connectionless protocol considered unreliable?
Because there is some level of uncertainty that the message is received, a connectionless protocol is considered unreliable.
Why are broadband cable operators exploring Internet protocol television (IPTV) integration strategies?
Broadband cable operators recognize that delivery of TV in an IP format is preferred by customers over legacy methods and are exploring various IPTV integration strategies to retain and possibly regain pay TV customers.
Which of the following is an example of how a connection-oriented protocol works?
Calling someone on the telephone and hearing somebody say "hello" on the receiving end before speaking.
Which signal parameters can be viewed in the frequency domain?
Channel amplitude, bandwidth, and nearby impairments.
What technology is plain old telephone service (POTS) built on?
Circuit switching.
What issues are caused by coding and compressing the video and audio of a TV channel for separate and distinct video and audio elementary streams (ES) of data?
Coding and compression differences create video and audio ES's of different lengths, which makes it difficult for a decoder to synchronize with and causes out-of-sync video and audio.
Chrominance
Color information
Group delay
Common sources are filters in diplex filters, high-pass filters, step attenuators, and in-line equalizers.
After stereo audio, what was the major disruption to TV technology that followed decades of few notable disruptions.?
Digital TV (DTV).
Which was the first version of the Data Over Cable Service Interface Specification (DOCSIS) that enabled multiple downstream and upstream channels to be used to transport data to and from a single modem?
Docsis 3.0
Why is measuring only the 8-VSB pilot frequency and its amplitude an inaccurate representation of the average power of the channel?
Errors that occur during transport can vary the relationship of the pilot signal strength to the data portion of the channel, the reason why measuring only the 8-VSB pilot frequency and its amplitude is an inaccurate representation of the average power of the channel.
What was an original requirement for Internet protocol (IP)-formatted digital TV (DTV) delivery to be considered Internet protocol TV (IPTV)?
Exclusive delivery over a managed network.
Modulation error ratio (MER)
Expressed in decibels (dB), indicates how far the received symbols are from the target symbol.
For reliable operation, the modulation error ratio (MER) of quadrature amplitude modulation (QAM) channels should be how much higher than the threshold that causes loss of reception by the receiver?
For reliable operation the MER of QAM channels should be at least 4 decibels (dB) higher than the threshold that causes loss of reception by the receiver.
In the Internet protocol (IP) suite, what are the IP packets called after the Network Access Layer adds the header at the beginning of the IP packet and data, called a trailer, at the end of the packet?
Frames.
What does the process known as grooming enable a broadband cable operator to do?
Grooming enables the operator to pick and choose channels from various sources to distribute.
What process enables the broadband cable operator to pick TV channels from various sources to create a new multiplex of their own?
Grooming.
Under what designation is high efficiency video coding (HEVC) defined by the Video Coding Experts Group (VCEG)?
H.265.
What is the Hex code and Character for binary code 1011000?
Hex code 58 and Character X
What does the modulation error ratio (MER) measurement of a quadrature amplitude modulation (QAM) channel tell a technician?
How close the QAM channel is to the cliff where the number of bit errors exceeds the forward error correction (FEC) capacity of the receiver and reception stops.
In an adaptive equalizer display, what do the vertical bars to the right of the incident signal, the eighth bar from the right, represent?
How much equalization is being applied to the channel.
In what applications are broadband cable operators implementing Internet protocol TV (IPTV) technology?
In TV everywhere applications.
In a broadband cable headend, in addition to receiving the channel, what else does the digital TV (DTV) receiver do?
In addition to receiving the channel, the DTV receiver decodes an MPEG-2 Transport Stream (MPEG-2 TS) containing one or more DTV channels.
Why are NAND and NOR gates the most used logic gates and categorized as universal gates?
In combinations of two or three, they can be configured to construct any other logic gate.
What term is often used incorrectly to express the data rate capacity of medium?
In digital communications, the term "bandwidth" is used to express the data rate capacity, in bits per second (bps), of transport mediums. Although usage of the term bandwidth to express data rate capacity is incorrect, this usage is so widespread it is better to understand the intention than be confused.
Using a signal level meter (SLM), what causes amplitude measurements of digital modulation channels to be substantially lower than the actual level?
In digital modulation channels, the wide distribution of energy causes amplitude measurements to be substantially lower than the actual level when using an SLM or spectrum analyzer with relatively narrow resolution bandwidth (RBW).
What are the states recognized by logic gates?
In logic gate operation, each terminal can be in only one of two states, a logical high or logical low, represented by a voltage level.
In the circular reference with the right triangle, what represents the amplitude or power in the sine wave?
In the circular reference with the right triangle, the triangle's vertical line length changing while the radius length remains constant during a full cycle represents the amplitude or power in the sine wave.
What are the three stages of pulse code modulation (PCM)?
In the three stages of PCM the analog signal is sampled, quantized, and encoded before being transported over a network medium.
What does quantizing do?
It rounds the values of sampled voltage levels to the closest numeric value in a numeric set.
How does Trellis coding provide error correction?
It adjust the symbol transitions to a robust set, enabling the receiver decoder to calculate the most probable transition, even if the received data is corrupt.
Why do digital modulation channels have measurable analog parameters?
It is based on modulating an analog RF carrier with digital data.
In a broadband cable network, why are power measurements taken by measuring a channel's voltage level across an assumed load impedance, rather than with a wattmeter?
It is usually easier and less disruptive to measure a channel's voltage level.
What typically defines individual downstream channel power levels and the number of channels?
Laser and amplifier specifications
Luminance
Light information
How is phase modulation (PM) like and unlike frequency modulation (FM)?
Like FM, the PM carrier is resistant to amplitude changes and related distortions, unlike FM, a PM carrier frequency remains the same as the carrier wave after modulation.
What is the most likely cause of linear distortion?
Linear distortion is generally caused by passive devices (cable, connectors, filters, etc.) reflecting energy or changing the shape of the channels or signals being transported through them.
What form of compression is Huffman coding?
Lossless.
Which Moving Pictures Expert Group (MPEG) standard is used for storage and playback on portable music players, commonly called MP3?
MPEG-1.
After which standard did the Moving Picture Experts Group (MPEG) abandon the sequential numbering of standards?
MPEG-4.
Which Moving Pictures Expert Group (MPEG) standard supports the high bit rate requirements of ultra-high definition TV (UHDTV)?
MPEG-H supports the high bit rate requirements of UHDTV.
When checking the in-channel frequency response (ICFR) of a quadrature amplitude modulation (QAM) channel in the customer premises, a frequency response with a repetitive ripple is a symptom of what?
Micro-reflections.
Pixels
Millions of light receptors
When Internet protocol (IP) hybrid set-top boxes (STB) are used to integrate Internet protocol TV (IPTV) into a broadband cable network, how much involvement does the operator have with virtual multichannel video programming distributors (vMVPD), streaming devices, and content listings?
Minimal.
What is the term for a receive function or protocol that reverses the processing or protocols involved to send a signal?
Peer communications requires a receive function or protocol that reverses the processing or protocols involved to send a signal.
What is implied when some say that telephone service is delivered using circuit switching technology?
Plain old telephone service (POTS), which is built on circuit switching technology with service provided over dedicated wires from an office that is located close to the customers
What is the generalized, industry definition of Internet protocol TV (IPTV)?
Rather than battle customer perception, the industry definition of IPTV has been generalized to multimedia formatted into the IP suite for transport over a packet-switched network that can be a private local area network (LAN), a managed IP network, or the Internet, an unmanaged, open network.
Which protocol is stacked on top of the user datagram protocol (UDP) to break the data into smaller units and add application-layer headers that contain a timestamp and sequence number for real-time TV delivery?
Real-Time Transport Protocol (RTP).
Cones
Receptors in the retina sensitive to color
Rods
Receptors in the retina sensitive to light
What geometric shape is a sine wave based upon?
Right - degree triangle
What could be possible causes of high signal levels into a cable modem, embedded multimedia terminal adapter (EMTA), gateway, and set-top box (STB)?
Signal levels that are too high—perhaps from a "hot" tap and a short drop—can create problems that are less intuitive to recognize than low signal levels.
What term describes the identification and removal of redundant data within a single frame of video?
Spatial compression.
In a digital modulation channel, what is the uniform distribution of energy as a function of frequency called?
Spectral density
How much does node splitting, the subdividing of fiber nodes into four smaller nodes, increase the average data rate capacity per homes passed (HP)?
Splitting a fiber node in four smaller nodes and reassigning the service groups into four smaller service groups increases the average data rate capacity per HP by a factor of four.
What allocates data bit rates according to scene requirements for the multiplexed DTV channels?
Statistical multiplexer.
What spectrum-saving technology has a portion of the broadband cable channel lineup switched for distribution on an "as-needed" basis?
Switched Digital Video (SDV).
Why is the transmission control protocol (TCP) unsuitable for voice over Internet protocol (VoIP) applications?
TCP is a connectionless protocol that operates without packet management.
Which layers of the Open Systems Interconnection (OSI) reference model and the five-layer Internet protocol (IP) suite will a technician most likely be familiar with?
Technicians working on a communications network are likely most familiar with the lower four layers of the OSI model and IP suite which are generally related to hardware, network access, and transport of signals.
In the Data Over Cable Systems Interface Specification (DOCSIS) structure, what does the Physical Layer specify?m
The DOCSIS Physical Layer specifies the modulation and access techniques for communications over a hybrid fiber/coax (HFC) network.
Which of the following is true about how DOCSIS network relates to the Internet protocol suite? Choose all that apply.
The DOCSIS Physical Layer specifies the modulation and access techniques for communications over a hybrid fiber/coax (HFC) network.
The Data Over Cable Systems Interface Specification (DOCSIS) MAC (Media Access Control) Layer maps to which Open Systems Interconnection (OSI) reference model layer?
The Data Link Layer.
What transformed two-way cable TV networks into a broadband cable networks?
The Data Over Cable Service Interface Specification (DOCSIS) defined methods for building and equipping a two-way cable TV network to carry high-speed Internet traffic, transforming it into a broadband network.
In the Internet protocol (IP) suite, which layer is the IP header information added to become an IP packet that contains the IP addresses of both hosts?
The Internet Layer.
In a NAND gate, what reverses the voltage state from that of an AND gate?
The NOT gate that follows the AND gate.
As defined by the Moving Pictures Expert Group (MPEG), what indicates the beginning of an MPEG-2 Transport Stream (MPEG-2 TS) packet?
The Sync Byte field, using hexadecimal number 47 (47HEX).
Why is amplitude measurement of a quadrature amplitude modulation (QAM) channel taken from the average power across the channel bandwidth, instead of the carrier?
The carrier in a QAM channel is 1.25 Mhz above the edge of the channel bandwidth
How does adaptive bit rate (ABR) technology improve the playback of streamed content on a client?
The client automatically adapts to the bit rate most appropriate for its display and the network conditions.
What is necessary to gather Proactive Network Maintenance (PNM) data from DOCSIS modems?
The data from PNM queries to DOCSIS modems is off-loaded from the cable modem termination system (CMTS) to a PNM server that compiles, stores, and manipulates the data into meaningful information. The PNM server and its software are configured by companies with specific expertise that present the PNM data in various formats.
The number of digital TV (DTV) channels multiplexed for modulation onto a single quadrature amplitude modulation (QAM) channel is dependent upon what?
The data rates of the compressed content and the data rate capacity of the QAM channel.
The digital aspect of the telegraph concerns the circuit having what?
The digital aspect of the telegraph concerns the circuit having two states—open, or off, when the switch is raised—closed, or on, when the switched is pushed down.
Bit error ratio (BER)
The number of received error bits divided by the total number of bits sent creating a ratio.
What was the original application for Internet protocol television (IPTV)?
The original application of IPTV enabled the telephone companies, using their existing twisted-pair local-loop infrastructure, to compete directly with the digital TV services provided by cable operators.
What do the rapid transitions of the pulses in digital modulation data create?
The rapid transitions of the pulses in digital modulation data create random power peaks that add and subtract to the channel's average power value.
What is stacked on top of the user datagram protocol (UDP) to provide
The real-time transport protocol (RTP) is stacked on top of UDP to provide real-time applications with specific functions.r
Why does the information in set-top box (STB) and modem diagnostic screens often appear cryptic to a customer?
The screens use initials, acronyms, and jargon intended for people that are familiar with the product.
Which of the following is true about pulse code modulation and sampling? Choose all that apply.
The second stage in the three-step pulse code modulation (PCM) process is quantize. Sampling is done by a pulse amplitude modulation (PAM) sampler that converts the amplitude levels of the analog signal into voltage levels over intervals of time.
In the audio compression coding schemes defined by ITU-T G.711 that compress 16-bit linear data down to 8-bit logarithmic data, what does the most significant bit (MSB), bit 1, identify?
The segment polarity.
In which forward error correction (FEC) stage does an algorithm calculate a 3- bit binary code that is transmitted as the 8-level symbols of eight-level vestigial sideband (8-VSB)?
The trellis encoder stage.
What do truth tables tell about logic gates?
The truth table enables every input combination and resultant logic gate function to be easily reviewed.
What enables assessment of upstream Data Over Cable Service Interface Specification (DOCSIS) channel parameters using the quadrature amplitude modulation (QAM) analyzer function of a signal level meter (SLM)?
The upstream channels from the built-in DOCSIS modem are optimized for the upstream path and the channel parameters displayed by the instrument.
How much do you know about QAM levels to data throughput rates?
The usable data rates for a 6 MHz wide 64-QAM channel are 27 Mbps. The usable data rates for a 6 MHz wide 256-QAM channel are 38.8 Mbps.
What is used with statistical multiplexing to avoid bit-overflow errors when the bit rate requirements of the multiplexed channels exceed the bit rate capacity of a 256-QAM channel?
There is a buffer for every input channel in a statistical multiplexer (statmux) that rate shaping algorithms use to adjust the flow through the buffers to prevent simultaneous peak bit rate usage by the channels in the multiplex, avoiding bit-overflow errors.
What happens if the same video-on-demand (VOD) movie session is ordered by three separate set-top box (STB) clients at three different times?
There is a separate unicast stream for each client, or three unicast streams.
- How is Fourier analysis used in orthogonal frequency division multiplexing (OFDM)?
To calculate the transformation of signals from the time domain to the frequency domain or from the frequency domain to the time domain.
Inverse fast Fourier transform (IFFT)
Transforms a signal from the frequency domain to the time domain.
Fast Fourier transform (FFT)
Transforms a signal from the time domain to a signal in the frequency domain.
Inverse discrete Fourier transform (IDFT)
Transforms multiple OFDM subcarriers from the frequency domain to the time domain.
Discrete Fourier transform (DFT)
Transforms serial data streams from the time domain to multiple subcarrriers in the frequency domain.
When viewing the return frequency spectrum with a spectrum analyzer, how can transient signals or ingress go unseen?
Transient signals or ingress, typical of the return path, appearing between spectrum analyzer sweeps could go unseen unless they remained until the next sweep passes.
Which protocol is used for applications that place a higher priority on the delivery of intact and error-free data, such as email and file transfers, and less on timely data delivery?
Transmission control protocol (TCP)
The Moving Pictures Expert Group (MPEG) intended the MPEG-2 Transport Stream (MPEG-2 TS) to be used for what applications?
Transport of MPEG-2 data on low-modulation level data streams.
The Moving Pictures Expert Group (MPEG) intended the MPEG-2 Program Stream (MPEG-2 PS) to be used for what applications?
Transport of digital TV (DTV) content over error-free media for recording and play-back or copied and pasted into computer file folders.
What is the ideal sampling rate for any analog signal?
Twice the highest frequency perceived by human eyes and ears.
Unless specified otherwise, how many bits are in a byte?
Unless otherwise specified, 1 byte contains 8 bits.
How are non-linear dBmV values converted to linear numbers for addition?
Use the formula A = antilog(dBmV/10) to calculate the antilogarithm of the nonlinear dBmV values.
Why is it necessary to compress video that is encoded into a digital signal?
Video encoded into a digital signal has data rates that range from over 200 megabits per second (Mbps) for standard definition TV (SDTV) to over 12,000 Mbps for high definition TV (HDTV). Distributing TV content at such high data rates to customers is impractical.
What feature simplifies navigation of set-top box (STB) electronic program guides (EPG)?
Voice activated remote controls simplify the EPG navigation process because the customer simply speaks a specific command into the remote control and the command is then given to the STB to execute.
It is based on modulating an analog RF carrier with digital data.
When of equal amplitude and bandwidth, the power level of a QAM channel is several decibel (dB) higher than an analog TV channel.
Which spectrum analyzer mode converts the analyzer from its normal frequency versus amplitude display, into a time domain display of time vs. amplitude?
Zero span.
In what scenario does an AND gate have a logical 1 output?
When all inputs are logical 1
What should be looked at when viewing a quadrature amplitude modulation (QAM) constellation to diagnose an issue?
When looking at a QAM constellation to diagnose an issue, various impairments can be identified by distinct constellation and symbol patterns.
Of the three numbers in every mobile phone, electronic serial number (ESN), mobile identification number (MIN), and system identification code (SID), which is used to validate whether a phone has service?
When powered on, a mobile phone seeks its SID on the control channel frequency that is broadcast by all the mobile service provider's base radio stations. If it receives the control channel and matching SID, the phone displays that it is receiving service, otherwise the phone displays a "no service" message.
What is the likely source of macroblocking in a hybrid fiber/coax (HFC) network if the modulation error ratio (MER) measurements are well above minimum levels?
When the digital TV (DTV) channel is multiplexed with other DTV channels in the headend.
Why would a technician ever need to view a set-top box (STB) diagnostic screen?
When troubleshooting a digital TV (DTV) issue, the technician can view the STB diagnostic to check the STB service authorization, verify STB reception of out-of-band (OOB) data, obtain quadrature amplitude modulation (QAM) channel information, confirm return path operation, and check internal STB health, such as temperature (model specific, if available)
Why would a technician ever need to view a set-top box (STB) diagnostic screen?
When troubleshooting a digital TV (DTV) issue, the technician can view the STB diagnostic to check the STB service authorization, verify STB reception of out-of-band (OOB) data, obtain quadrature amplitude modulation (QAM) channel information, confirm return path operation, and check internal STB health, such as temperature (model specific, if available).
What is significant about a 3-decibel (dB) power gain or loss?
Whether doubling the power by 10 watts (W) or 50,000 W, the power gain is 3 dB, and cutting the power in half by 5 W or 25,000 W is 3 dB less power.
What can be said about disruptive technologies?
With mainstream acceptance, what was once called disruptive is eventually deemed innovative.
Why are quadrature amplitude modulation (QAM) channel amplitude measurements taken from the average power across the channel bandwidth rather than peak voltage levels?
With the carrier suppressed, the QAM channel's amplitude measurement is taken from the average power across the channel bandwidth, from the lower to upper edge of the channel.
What group was formed by the International Telecommunication Union (ITU) with the same goal as the Moving Pictures Expert Group (MPEG)?
With the same goal as MPEG, the ITU formed the Video Coding Expert Group (VCEG).
