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4:3—aspect ratio: This is
a traditional TV aspect ratio, which
refers to
the screen’s width as compared
to its height.
16:9—aspect ratio: This is
the aspect ration for a "Widescreen" TV
format, which more closely resembles
a movie screen than a traditional
TV.
5.1 Audio
Format—This is a digital
audio recording and playback system
for home theater. It includes five
channels (left, right, center, rear/surround
left and right) plus a subwoofer
channel. The major 5.1 channel standards
are Dolby AC-3 and Philips Musicam.
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A
Analog TV—The technology
in use for more than 50 years to
transmit
conventional radio and TV signals.
Vinyl recordings and motion picture
films are examples of analog technology. "Standard" television
broadcasts analog TV. Analog signals
vary continuously, representing fluctuations
in color and brightness.
Aspect Ratio—The ratio of
television picture width to height.
In NTSC and PAL
video, the present standard is 4:3.
In widescreen
video, it is typically 16:9.
Advanced
Television Systems Committee (ATSC)— The
committee responsible for digital
television standards and development,
as well as all 18 formats of DTV.
ATSC—An acronym for Advanced
Television Systems Committee, and
the name of the DTV
system used by broadcasters in the
U.S. (akin to European COFDM).
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B
Bandwidth—The amount of spectrum
available to each communications
licensee.
For digital conversion, the FCC
has allocated 6 MHz (megahertz) of
UHF bandwidth for each broadcaster.
This amount of bandwidth can carry
up to four multicast digital signals,
a high-definition signal, data, or
a combination of these elements.
Barn Doors—A term used in
television production to describe
the effect that occurs when a 4:3
image is viewed on a 16:9 screen.
Viewers see black bars (“barn doors”)
on the sides of the screen.
Binary—A numeral system that
represents numeric values using two
symbols, usually 0 and 1. Owing
to its straightforward implementation
in electronic circuitry, the binary
system is used internally by virtually
all modern computers. (source wikipedia.org)
Bit—A binary digit—the smallest
unit of data in a digital system.
A bit is a single 1 or 0.
A group of bits, such as 8-bits
or 16-bits,
compose a byte.
Byte—A group of bits.
The number of bits in a byte depends
on the processing system being used.
Typical byte sizes are 8, 16, and
32.
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C
CableCARD—Digital
cable customers may obtain this security
card in order to view high-definition
scrambled programming and premium
services without a set-top box.
Codec (short for “coder-decoder”)—a
device that converts analog video
and audio signals into a digital
format for transmission. It also
converts
received digital signals back into
an analog format.
COFDM: (acronym for “Coded
Orthogonal Frequency Division Mulitiplexing”)—The
DTV standard used in Europe (akin
to ATSC in the
U.S.).
Compression—The process of
fitting a large file into a space
that is many times smaller. In the
case of video, the method used for
the DTV standard
is MPEG-2,
which can take four full-range channels
of programming and data and compress
them into the same space currently
occupied by a single analog channel.
Computer Input—Some HDTV
sets have an input (D-SUB/DVI)
that allows the TV set to be connected
to a
computer.
CRT (Cathode-Ray
Tube)—A CRT ("picture
tube") is a specialized vacuum
tube in which images are created
when an electron beam scans back
and forth across the back side of
a phosphor-coated screen. The regular "direct-view" TVs
most people grew up watching have
a single large picture tube, while
CRT-based rear-projection and front-projection
TVs use three CRTs: one each for
the red, green, and blue primary
colors. Each time the beam makes
a pass across the screen, it lights
up a horizontal line of phosphor
dots on the inside of the glass tube.
Images are created by rapidly drawing
hundreds of these lines from the
top to the bottom of the screen.
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D
Datacasting—Digital television
allows for the transmission of not
only digital sound and images, but
also digital data (text, graphics,
maps, services, etc.). This aspect
of DTV is the least developed; but
in the near future, applications
will likely include interactive
program
guides, sports statistics, stock
quotes, retail ordering information,
and the
like. Datacasting is not two-way,
although most industry experts expect
that set-top box
manufacturers will create methods
for interaction. By integrating
dial-up
Internet connections with the technology,
simple responses—placing orders
for a necktie like Jim Lehrer’s
or answering viewer polls—will
be possible using a modem and either
an add-on keyboard
or the set-top’s remote control.
DBS—See direct
broadcast via satellite.
Digital Cable—A service provided
by many cable providers which offers
viewers more channels, access to
pay-per-view programs, and online
guides. Digital
cable is not the same as HDTV
or DTV; rather,
digital cable simply offers cable
subscribers the options of paying
for additional services.
Digital Cable
Ready (DCR)—A "plug-and-play" DTV
for digital cable customers that
plugs directly into the cable jack
and does not require a separate set-top
box.
Digital Television (DTV)—Is
a telecommunication system for broadcasting
and receiving moving pictures and
sound by means of digital signals,
in contrast to analog signals used
by analog (traditional) TV. DTV uses
digital modulation data, which is
digitally compressed and requires
decoding by a specially designed
television set, or a standard receiver
with a set-top box. (source wikipedia.org)
Digital Tuner or Digital
Receiver—A
digital tuner serves as the decoder
required to receive
and display digital broadcasts. A
digital tuner can down-convert
broadcasts for an analog TV or provide
a digital signal to a digital television.
It can be included inside TV sets
or via a set-top
box.
Direct Broadcast via Satellite
(DBS)—Subscribers receive programs
via a small satellite dish. The
signal
is NTSC, digitized
and compressed
via a proprietary format and decompressed
by a set-top box.
Some DBS services offer DTV
and HDTV content.
Digital Light
Processing (DLP)—A trademark
owned by Texas Instruments, representing
a technology used in projectors and
video projectors. It was originally
developed in 1987 by Dr. Larry Hornbeck
of Texas Instruments. In DLP projectors,
the image is created by microscopically
small mirrors laid out in a matrix
on a semiconductor chip, known as a
Digital Micromirror Device (DMD). Each
mirror represents one or more pixels
in the projected image. (source wikipedia.org)
Dolby Digital—The approved
5.1-channel (surround-sound) audio
standard for ATSC digital television.
Six distinct audio channels are
used: left, center, right, left rear, right
rear (indicated by the "5"), and
a subwoofer (indicated by the ".1").
Dolby Surround (Dolby Stereo)—Four
audio channels (left, center, right,
and surround) converted to two channels
referred to as right-total and left-total.
Downconverting—Process by
which a high-definition signal is
converted to a standard-definition
picture.
D-SUB—The D-subminiature or D-sub is a common type of electrical connector used particularly in computers. Calling them "subminiature" was appropriate when they were first introduced, but today they are among the largest common connectors used in computers. (source wikipedia.org)
DTV—See digital television.
DVI—The Digital Visual Interface (DVI) is a video interface standard designed to maximize the visual quality of digital display devices such as flat panel LCD computer displays and digital projectors. (source wikipedia.org)
Digital Video Recorder (DVR)—a
video recording device that uses
a hard disk drive or optical disk drive,
instead of a VCR tape, to record
programs.
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E
Enhanced DefinitionTelevision
(EDTV)—EDTV refers to a complete
product/system that receives ATSC
terrestrial digital transmissions
and decodes all ATSC table 3 video
formats, has active vertical scanning
lines of 480 progressive (480p)
or higher and receives, reproduces,
and/or outputs Dolby
Digital audio.
EDTV Monitor—EDTV
monitor refers to a monitor or display
that has active vertical scanning
lines of 480 progressive (480p) or
higher.
EDTV Tuner—EDTV
tuner refers to a RF receiver that
receives ATSC terrestrial digital
transmissions and decodes all ATSC
table 3 video formats. It outputs
the ATSC table 3 720p and 1080 i/p
and 480p formats with minimum active
vertical scanning lines of 480. Alternatively,
the output can be a digital bit stream
output capable of transporting 480p,
except the ATSC table 3 480i format
can be output at 480i. It also receives
and reproduces, and/or outputs Dolby
Digital audio.
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F
FCC—The Federal Communications
Commission; the body that governs,
among other things, radio and television
broadcasting in the U.S.
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H
High-Definition Television (HDTV)—HDTV
refers to a complete product/system
that receives ATSC terrestrial digital
transmissions and decodes all ATSC table 3 video formats, has active
vertical scanning lines of 720 progressive
(720p), 1080 interlaced (1080i) or
higher. Is capable of displaying
a 16:9 image and receives, reproduces,
and/or outputs Dolby
Digital audio.
HDTV Monitor—HDTV
monitor refers to a monitor or display
that has active vertical scanning
lines of 720 progressive (720p),
1080 interlaced (1080i) or higher
and is capable of displaying a 16:9
image. Manufacturers are required
to disclose the number of vertical
scanning lines in the 16:9 viewable
area, which must be 540p, 810i or
higher to meet the definition of
HDTV.
HDTV-ready—Term
used to describe TVs that can display
digital high-definition TV formats
when connected to a separate HDTV
tuner. These TVs generally have built-in
tuners for receiving regular NTSC
broadcasts, but not digital. An HDTV-ready
TV may also be referred to as an "HDTV
monitor."
HDTV Tuner—Often
called an ATSC receiver
or HDTV tuner, allows reception of ATSC digital
television (DTV)
signals broadcast over-the-air by
TV stations in North
America and South Korea. Such tuners
may be integrated into the television,
VCR, digital video recorder (DVR),
and set-top box which provides audio/video
output-connectors of various types.
(source wikipedia.org)
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I
IEEE—Institute of Electrical
and Electronic Engineers; a professional
organization that helps set transmission
system standards.
Interlaced Scan—A way to
scan vertical lines onto a TV picture
by scanning all the odd lines first,
then filling in the even lines.
I/O—“input/output”; typically
refers to sending data to and from
devices.
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L
LCD (Liquid
Crystal Display)—Liquid Crystal
Display technology is one of the methods
used to create flat-panel TVs. Light
isn't created by the liquid crystals;
a light source (bulb) behind the panel
shines light through the display. The
display consists of two polarizing
transparent panels and a liquid crystal
solution sandwiched in between. An
electric current passed through the
liquid causes the crystals to align
so that light cannot pass through them.
Each crystal acts like a shutter, either
allowing light to pass through or blocking
the light. The pattern of transparent
and dark crystals forms the image.
LCD technology is used in flat-panel,
rear-projection, and front-projection
TVs.
LCoS (Liquid
Crystal on Silicon)—A projection
TV display technology that sandwiches
a layer of liquid crystal between a
cover glass and a highly reflective,
mirror-like surface patterned with
pixels that sit on top of a silicon
chip. These layers form a microdisplay
that can be used in rear-projection
and front-projection TVs. Manufacturers
use different names for their LCoS-based
technologies. JVC uses D-ILA™ or
HD-ILA™, while Sony uses SXRD™.
Letterbox—On a TV screen
with standard aspect ratio (4:3),
letterboxed videos appear with horizontal
black bars above and below the image.
This is a method for displaying the
entire picture, as seen in a movie
theater.
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M
MPEG-2—Compression standards
for moving images and audio set by
the Motion Pictures Expert Group
(MPEG),
an international committee of industry
experts. MPEG-2 is the basis for ATSC
digital television transmissions
in the U.S.
Multicasting—The ability
to send more than one channel of
programming
within the allotted channel spectrum.
While analog
channels have traditionally used
a standard amount of spectrum (represented
by each click on your tuner dial),
digital channels can squeeze up
to
four channels into their spectrum.
(See also simulcast.)
For example, KET currently multicasts
programming on channel 46 in Lexington.
Viewers in that service area with
digital sets simply tune to channel
46 and then choose among four different
services: 46-1, 46-2, 46-3, or 46-4.
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N
National Television System Committee
(NTSC)—Established our North
American 525-line analog broadcast
TV standard about 60 years ago.
Although it is referred to as a "525-line" standard,
we're only able to see 480 lines
on a TV display. The ATSC digital
broadcast standard will eventually
replace NTSC standard.
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P
PAL—Phase Alternation Line
(PAL) is the analog television display
standard that is used in Europe and
certain other parts of the world.
The U.S. uses the American National
Television Systems Committee (NTSC)
standard.
Pixel—A combination of the
words “picture” and “element.” A
pixel is the smallest picture element
in a TV image. The more pixels in
an image, the greater the resolution.
Pixels Per Inch (PPI)—The
measure of the sharpness (that is,
the density of illuminated points)
on a television display screen.
Plasma—A
display technology enabling thin,
lightweight TVs that can be hung
on the wall. Plasma TV pixels are
composed of gas-filled cells where
an electric current is applied to
create the TV image.
Progressive Scan—TV images
are displayed using vertical lines.
Progressive scan is a way to produce
the vertical lines of a TV picture
by scanning all the lines consecutively
(progressively).
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R
Rear-projection
TV—As the name defines, rear-projection
TV’s display a TV image by projecting
images on the back of a screen. These
TV’s are typically referred to
as "big-screen" TVs. Digital
microdisplay rear-projection technologies,
including DLP, LCD, and LCoS, are most
common now, and allow for more lightweight,
space-saving designs. Resolution—The amount of
lines and dots (pixels) that make
up a TV image. Typically, the higher
the number of lines or pixels, the
sharper and more detailed the picture
will be.
Resolution
is measured in a number of ways,
depending
upon the medium used. For example,
digital TVs describe their resolutions
in terms of the number of pixels
or dots that make up the picture
along
the vertical and horizontal axes.
One of the high-definition picture
formats is composed of 1080 active
lines, and each line is composed
of
1920 active pixels. Therefore, each
frame has more than 2 million (1080 X 1920 = 2,073,600)
color pixels creating the image.
By
way of contrast, today’s typical
analog television is roughly equivalent
to
480 active lines, with each line
holding about 440 pixels. So, each
frame has
slightly more than 200,000 color
pixels in use creating the image.
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S
Set-top Box (STB) or Set-top
Converter Box—This unit accompanies
the viewer’s TV, receives the
digital TV signal, and then
sends that signal
to the television. For analog TVs,
the signal will first be downconverted;
for digital-ready TVs, the
digital
signal will be passed directly to
the television.
Simulcast—The broadcasting
of the same program on two different
channels or frequencies. Until the
DTV transition deadline, much of
broadcast networks' DTV content must
be simulcast with regular TV.
Standard Definition TV (SDTV)—SDTV
is the baseline display and resolution
for both analog and digital. Transmission
of SDTV may be in either the traditional
(4:3) or wide-screen (16:9) format.
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T
Terrestrial Broadcasting—A
broadcast signal transmitted “over-the-air”
from a ground-based transmitter to
an antenna.
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U
Upconversion—The term used to describe
the conversion of a lower resolution
to a higher one. This process uses
technology to increase the number
of pixels, frame rate or scanning
lines.
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V
Viewing Angle—A TV's maximum usable
viewing range from the center of
the screen. 180° would be the
maximum viewing angle.
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W
Widescreen—Widescreen generally
refers to an aspect ratio of 16:9,
which is the optimum viewing ratio
for DTV and HDTV broadcasts. Traditional
TV sets have an aspect ratio of 4:3
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