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What do 1080i and 720p mean?
The most common high definition formats are: 720p and
1080i. The 720p format makes a picture with 720 vertical
lines, each with 1280 pixels horizontally. It uses
progressive scanning, like computers, which sends a
complete picture 60 times per second. The 1080i format
creates a picture with 1080 vertical lines, each with
1920 pixels horizontally. 1080i uses interlaced
scanning, like traditional TV, which alternates sending
odd lines and even lines and thus sends a complete
picture 30 times per second. Both formats make for a
clearer, sharper picture than analog television.
What is 1080p?
1080p resolution is a fairly new format that is 1080
lines of progressively scanned video. A television set’s
inputs must be able to process a 1080p signal and be
designed to accept 1080p/24/30/60 fps signal from an
external 1080p progressive source.
What is the difference between
Digital Television (DTV) and High Definition Television
(HDTV)?
DTV is the umbrella term used to describe the new
digital television system adopted by the FCC in December
1996. DTV is a new way of transmitting television
signals. It will eventually replace analog, the way
television has been transmitted for the last 50 years.
HDTV uses the entire “channel” and offers superior
picture and CD quality sound.
Is all digital programming in high
definition?
No. Digital programming can either be in standard
definition (SD) or high definition (HD). Standard
definition broadcasts can have a format of either 480i
or 480p. High definition broadcasts can be e720p, 1080i
or 1080p format.
What are the advantages of High
Definition Television?
The first noticeable difference of high definition TV
from the analog television system is that the screen is
much wider. With analog TV, the width of the picture is
divided by the height of the picture and will always
produce a 4/3 ratio. High definition television, on the
other hand, has a width to height ratio of 16/9, which
closely approximates that of a movie screen. The second
advantage is that HD has over six times the sharpness
and clarity of analog TV. The HDTV picture contains 1080
vertical picture elements (pixels) by 1920 horizontal
pixels for a total of over 2.0 million pixels. The
current standard definition picture contains only 480
vertical pixels by 720 pixels for a total of 345,600
pixels. Third, the color resolution of HDTV is also more
than twice the resolution of analog. High definition
television also has six channels of CD-quality surround
sound (left, right, center, left rear, right rear, and
low frequency effects).
How can I find out what programs
are broadcast in High Definition?
TitanTV takes a member’s street address and predicts the
digital over-the-air stations one can expect to receive.
Programs available in high definition are marked with a
red HD symbol in the program grid cell. In addition to
providing listings and HD designation information for
over-the-air channels, TitanTV also provides this
information for digital cable and satellite lineups.
What do I need to start watching TV
in HD?
First, you need a digital TV and a digital TV tuner. You
can buy the tuner and display in an integrated DTV, with
both built in. If you purchase a DTV monitor (an analog
TV with the capability to display DTV) you will need to
buy a DTV tuner in a separate set-top box. DTV tuners
can be included in a DTV satellite receiver, a DTV
capable digital cable box or an over-the-air DTV tuner.
Second, you must be able to receive a digital signal
at your location. Depending on where you live, DTV
signals can be delivered through digital cable, digital
satellite or an over-the-air antenna that receives
digital signals. TitanTV provides a comprehensive list
of the digital channels available at your address. To
receive a free over-the-air signal, you will need an
over-the-air antenna. The type of antenna required
depends on your location and distance from transmitters
and local terrain. In many instances, a rooftop antenna
will be most effective. To find out what antenna works
for your home, use TitanTV’s antenna selector section.
Third, a program must originate in HDTV and be
broadcast in HDTV. Just because you have an HDTV set and
signal does not mean that everything you watch will be
in High Definition. And just because a program arrives
through a digital cable or a digital satellite does not
mean it is in HD. Much of the programming today, even
that received from a digital satellite, digital cable,
or even a digital channel broadcast over the air, is
delivered in what is known as standard definition. You
will get a better picture than you would get with the
analog broadcasts TV has used for all these years,
because a digital picture will be free from the ghosts
and snow that can plague analog transmissions. A
standard definition digital picture will be good, but
not nearly as sharp and crisp as HD.
What types of HD sets are there?
There are different types of high definition TV sets
suited for various room layouts, budgets and priorities:
Flat-panel LCDs and plasma TVs offer space-savings
but may be more expensive than other options.
Rear projection TVs offer large images at more
affordable prices but may not fit in certain rooms given
their size.
Front projectors offer the largest HD images but room
brightness have adverse effects on the overall viewing
experience.
Direct-view HDTV sets offer reliability of television
picture tube technology but also can be fairly large in
size.
What is the difference between LCD
and Plasma TVs?
The foundation of the Plasma TVs is over a million tiny
glass cells that are charged with a mixture of neon and
xenon. Behind these cells are colored phosphors, which
are chemical compounds that emit light when energized.
Each cell has three phosphors; one red, one blue, and
one green. When activated by an electrode, the plasma
cells emit invisible UV light. The UV light strikes the
red, green and blue phosphors on the back of the display
and thus creates the pixels that form the image you see
on the screen.
LCD (Liquid Crystal Display) technology works
differently. Liquid is suspended between two transparent
panels. Within the liquid are crystals that, when
activated by voltage, re-position themselves so that
they either allow the light to pass through the panel
and/or block the light. This process is similar to
turning on and off a million light bulbs. Fluorescent
tubes behind the panels supply the light source. Both
the lit and unlit crystals create visible pixels that
cumulatively compose the image on the screen.
Is there a cut-off date by which
broadcasters must be broadcasting in digital?
Yes. February 17, 2009, is the date that broadcasters
must end transmitting their analog television signals.
What is multicasting?
A digital signal has the capability for up to19.4 Mbs of
content—allowing a station to provide multiple Standard
DTV channels in digital, a process called multicasting.
This means that a station can transmit multiple channels
in the same bandwidth instead of just one.
Why do digital stations sometimes
have two channel numbers?
The FCC has assigned a digital or RF channel number to
all digital stations. In addition, some local affiliates
are using Program and System Information Protocol (PSIP)
to remap to their analog channel numbers. PSIP is data
that is transmitted along with a station’s DTV signal
that tells DTV receivers important information about the
station and what is being broadcast (what channel to
tune to for reception of the station, helps maintain
current (analog) channel number branding, tells receiver
whether multiple programs are being broadcast, etc.).
How do I know if a station is
multicasting?
TitanTV takes your street address and predicts what
digital over-the-air stations you can expect to receive,
including stations that are multicasting. TitanTV
presents all sub-channels that a station has programming
on. These stations are typically represented with a
major channel and a minor channel (example: 54-1, 54-2,
54-3, etc.)
What types of information
(programming) is typically multicast?
Local affiliates can broadcast any type of programming
content on their sub-channels. Common programming that
is available from stations that are multicasting
include: weather radar, sports, re-broadcasts of local
news, educational programming and much, much more.
Why do stations use their digital
spectrum to multicast?
Many broadcast stations choose to multicast programming
like Weather and Traffic. This gives viewers more
programming content (for free, over-the-air) and
broadcasters more advertising opportunities. Some
stations choose to multicast all of the time in addition
to their high definition broadcast.
What is datacasting?
Datacasting is the use of digital television bitstreams
to send data packets in place of television. An 8-VSB
terrestrial broadcast signal sends up to 19.4 Mbps of
data directly to the receiver. A standard DTV program
requires only 4-5 Mbps of data for DVD quality
television. This leaves about 15 Mbps of unassigned
bandwidth available 24 hours a day, 7 days a week from
8-VSB broadcast stations. Datacasting provides data at
high speed, utilizing wireless transmission in
point-to-multipoint (one message sent through a network
multiple times for each user) mode rather than the
Internet’s point-to-point transmission.
Point-to-multipoint allows all recipients to receive the
signal at its highest quality.
What stations are datacasting?
Datacasting is still a fairly new component to digital
television and many stations do not have immediate plans
for datacasting. The opportunities and technology
continue to be researched with public television
stations the primary datacasters at this time.
Why would a broadcaster choose to
datacast?
Broadcasters may choose to use their digital spectrum to
broadcast additional information and content of their
own or they may choose to ‘rent’ their spectrum to other
datacasters to generate additional revenue.
How can I as a consumer benefit
from datacasting?
Datacasting provides consumers with the opportunity to
receive additional content such as video, music, games
and many other options.
Glossary of HD Terms
| 16:9: |
Ratio of the
dimension (also know as aspect ratio) of a
widescreen TV. While the typical analog TVs have
square screens, newer TVs look like movie
theater screens. DVDs and high definition
broadcast are formatted for the 16:9 ratio.
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| 4:3: |
Ratio of the
dimensions of a traditional TV set. This shape
is suitable for TV broadcasts but is not wide
enough for big-screen movies. To show these on a
traditional TV, the movies have to be edited
(trimmed by 25 percent) or be shown in letterbox
format which involved blacking out a strip at
the top and bottom of the TV screen. |
| 8-VSB: |
The
transmission standard for digital TV in the US,
endorsed by the Federal Communications
Commission in 2001. The letters indicate that it
is the number 8 mode of vestigial sideband
modulation. All receivers made in the US are
8-VSB compatible. |
| NTSC: |
National
Television Standards Committee or the body that
originally developed the black and white, and
subsequently color television system that has
been in use for over 50 years in the US and
elsewhere. |
| ATSC: |
Advanced
Television Systems Committee or the group that
formed in 1993 and offers technical guidelines
on how digital television should be broadcast.
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| Aspect Ratio: |
The proportion
of a TV screen’s width to its height. Most TVs
are either 4:3 or 16:9. |
| Active Scan
Lines: |
The tiny rows
of pixels on a television screen. There are 480
lines on a typical analog NTSC TV screen and
1,080 on an HD set.
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| CableCARD: |
A device
supplied by a cable company that slides into a
set-top box or television. The card identifies
the user account and turns off protection
safeguards to HDTV channels can be viewed. |
| Plug-and-play
or digital cable ready: |
A DTV or other
device for digital cable customers that plugs
directly into the cable jack and does not
require a separate set-top box. Plug-and-play TV
owners must obtain a CableCARD from their cable
company in order to view scrambled programming
services. |
| HDTV
(high definition TV): |
A TV set with a
built-in tuner that can show HD broadcasts in
true HD resolution. Also refers to the
broadcasts themselves. According to the Consumer
Electronics Association, a fully integrated TV
set will receive all ATSC terrestrial digital
transmissions and decode all ATSC Table 3 video
formats. It must display active vertical
scanning lines of 720 progressive (720p), 1080
interlaced (1080i) or higher in a 16:9
widescreen aspect ratio. It must also receive
and decode or pass-through for decoding Dolby®
Digital audio. It must also receive and decode
or pass through for decoding 5.1 digital
surround sound. |
| Standard
Definition Television: |
Digital
broadcast that has 480 active scan lines (like
traditional analog signals). The format does
have clearer sound and a picture free of
interference. According to the CEA, SDTV now
refers to fully integrated television receivers
that receive all ATSC terrestrial digital
transmissions and decode all ATSC Table 3 video
formats to produce a usable picture. It can have
active vertical scanning lines less than EDTV
quality. No aspect ratio is specified and it
must receive some form of usable audio signal.
|
| Letterbox: |
Format
sometimes used to show wide-screen movies on
traditionally shaped 4:3 TV sets. A letterboxed
movie has black bars above and below the image.
|
| Receiver: |
Device that
tunes an analog or digital TV broadcast. A
digital receiver, which also decodes the signal,
can be built into the TV set or work as a part
of another piece of hardware like a set-top box.
A digital TV receiver pulls in frequencies from
a TV antenna, satellite signal or cable
connection. |
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