FREQUENTLY ASKED QUESTIONS - FAQ'S
What Is Digital Television?
Why Would I Want To Buy An HDTV?
Is DTV The Same As High-Definition Television?
What Does “HDTV Ready” Mean?
What Are The Minimum Features A TV Must Have To Qualify As
A
High Definition TV (HDTV)?
Why Are There Different Forms Of DTV?
Why So Many Formats Within DTV?
The ATSC Table 3 Shows Many Formats For HDTV And SDTV
Transmission.
How Will My HDTV Be Able To Display All These Formats?
How Will I Receive HDTV?
When Broadcasters Begin Transmitting HDTV Signals,
What Happens To Current Analogue Televisions?
How Long Will Conventional Analogue TV Signals Be
Available?
Am I Getting DTV From My “Digital“ Cable,
Satellite, Or MMDS Service Provider?
What About The TV I Own Now And The Next TV I Buy?
What Features are Important When Buying an HD Set?
When Should I Buy An HDTV?
What Is Digital
Television?
Digital Television (DTV) is a new standard
established in both Canada and the U.S.A. for the broadcast of television
pictures, sound, and data.
In November 1997, Industry Canada adopted the
Advanced Television Systems Committee (ATSC) standard for DTV. The ATSC standard includes
18 DTV broadcast formats, all of which fall under one of two categories: High-Definition
Television (HDTV) or Standard-Definition Television (SDTV).
In the Fall of 2000, the U.S. Consumer Electronics Association issued more detailed
terminology for the various classes of reception and display for digital televisions, and
introduced a third category, “Enhanced Definition Television”, (EDTV),
which fits in between SDTV and HDTV. These definitions also apply to the
Canadian market.
It is very important to recognize the
differences between the two sets of standards. The ATSC’s 12 Standard Definition and
6 High Definition formats relate to the broadcast of Digital TV. The CEA terminology
for Standard Definition, Enhanced Definition and High Definition relate specifically to
hardware reception and display capabilities.
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How Is DTV
Different From What We Have Today?
For the past 40
years televisions signals have employed a standard known as NTSC (National Television
Systems Committee) for production, transmission and display. The NTSC standard is known as
analogue signal in that it is created with continuously varying voltage levels or
electrical waves, which may be adversely affected by every step in the production
-distribution process. To conserve the limited transmission spectrum, the color portion of
the signal and the luminance (black and white image) are combined in the production stage
and retained in this composite form until separated at the television receiver into the
primary components of red, green and blue (R,G,B) at the picture tube.
DTV is the new
generation of television. DTV signals are generally recorded, distributed and transmitted
in a digital component format. Being digital, the signal generally experiences minimal
loss of quality from the studio or mobile cameras to the homes. The color is more
faithfully reproduced through the entire process from the originating R,G,B components in
the camera to our home television displays. This ensures sharper pictures, and greater
color fidelity. Potentially studio origination quality can be delivered to the home
without transmission or distribution losses. And this can be done at varying levels of
picture detail depending on the content needs, broadly described as Standard Definition
television (SDTV), Enhanced Definition television (EDTV), and High Definition.
The North American
DTV standard known as ATSC (Advanced Television Systems Committee) is basically a highly
compressed stream of 1’s and 0’s, known as bits, which represent the pictures,
sound and data associated with the television signal. These bits are then converted into
pixels (short for Picture Elements), which can be thought of as a single dot of light on
the TV screen. The greater the number of pixels, the sharper or better defined the picture
will be. In its “finest” form HDTV can display up to 10 times as many pixels as
most analogue televisions.
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Why
Would I Want To Buy An HDTV?
There is no question
that HDTV is much better than the analogue system we've been used to.
Vastly Superior Picture Performance. Broadcasters are now be able to transmit
pictures with a quality far superior to today’s NTSC television system or any other
picture source currently available (e.g. VCR, DVD and Laser Disc).
New
Wide screen Format. HDTV
provides for a wide screen presentation similar to what you see in movie theatres. The new
screen has a width-to-height (or aspect) ratio of 16:9 compared to today’s 4:3
width-to-height ratio on conventional television sets.
Wider Aspect Ratio. See the illustration
below. |
Clearer Pictures. HDTV eliminates “snow” and
ghosting.
Better Color. HDTV delivers exceptionally vivid
colors – including subtle purples and reds – and eliminates any bleeding
of colors at the edges...
Multi-Channel Digital Sound
Quality. HDTV provides
highly advanced Dolby® Digital Audio, also known as AC3, with 5.1 discrete audio
channels.
Future Possibilities. HDTV uses a high bit-rate channel, which will
mean broadcasters will be capable of transmitting new value-added services, such as
Interactive TV, to consumers in the near future.
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Is DTV the Same as High-Definition Television?
HDTV is DTV at it’s finest. HDTV is
the best option in the range of DTV transmission formats.
Each of the eighteen possible broadcast
formats within the ATSC standard has a specified number of active horizontal scanning
lines used to create a TV picture. The greater the number of these scanning lines, the
greater the level of vertical detail, in either progressive or interlaced mode. Six of
ATSC’s eighteen transmission formats use 1080 or 720 active scanning lines, in either
“p”-progressive, or “i”-interlaced display. This is true HDTV. The
remaining twelve transmission formats use 480 active scanning lines, and are classified as
Standard Definition. TV set manufacturers may also use the term Enhanced Definition (EDTV)
to define the display of an SD broadcast in a 480 line progressive format. Thus
Standard Definition Television (SDTV) would be any display of digital transmission, down
converted to 480 line interlaced format (480i).
The following comparison chart indicates
attributes of the various formats. Note that the SD, ED, and HD formats all require either
an ATSC compliant built in tuner or an add-on ATSC set top box. Also remember that an ATSC
compliant tuner or set top box must be able to receive and decode all 18 broadcast
formats, and allow for a usable display of the picture.
|
Analogue |
SDTV |
EDTV |
HDTV |
Aspect Ratio |
4:3 |
4:3 or 16:9 |
4:3 or 16:9 |
16:9 |
Pixels per line |
450 (equiv.) |
708 - 720 |
708 - 720 |
1280 (720p)
1920 (1080i) |
Active lines/picture |
480i |
480i |
480p |
720p or 1080i |
Total number of pixels |
253,000 +/- |
<480,000 |
>480,000 |
921,600 (720p) 2,073,600 (1080i) |
Progressive Scan |
No |
No |
Yes |
Yes |
Interlaced Scan |
Yes |
Yes |
Yes |
Yes |
Pictures/sec. |
30 |
30 |
60 |
60 (720p)
30 (1080i) |
Audio |
2 channel - stereo |
2 channel digital |
Dolby Digital |
Dolby Digital |
Broadcast Formats |
1 Analogue |
12 Digital formats |
12 Digital formats |
6Digital formats |
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What
Does “HDTV Ready” Mean?
All televisions are Digital TV-Ready when
connected to a DTV set-top box. This will produce an NTSC (analogue) quality picture. As a
result, it is important to understand the different terms used to describe your
televisions capabilities.
- An INTEGRATED Digital
Television, be it SD, ED, or HD, must meet the specific display and audio criteria for its
class, utilizing an ATSC compliant BUILT IN tuner.
- A DIGITAL READY
Television, whether SD, ED, or HD, must also meet the specific display and audio
characteristics of its class, utilizing an add-on DTV set-top box (STB) to decode the
signals.
- HDTV-READY means the TV has a designated HDTV input, but
does not have an ATSC tuner built in. These TVs require a DTV converter box that will
allow the TV to display a HDTV program in its native 720p or 1080i transmission format, as
well as reproducing or passing through Dolby Digital audio, which may include up to 5.1
discrete audio signals. The image on-screen must be in a 16:9 aspect ratio. Most HD sets
are built with a screen in that aspect ratio, however, letterboxing a 720p or 1080i
broadcast on a 4:3 display will still qualify as High Definition. Your set manufacturer
will identify the number of active scanning lines in these cases.
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What
are the Minimum Features a TV Must Have to Qualify as a High Definition TV (HDTV)?
The minimum
performance attributes for HDTV are:
- Picture
Quality: vertical display
resolution of 720p,resulting in 921,600 pixels per frame, or 1080i or higher delivering a
picture of over 2,000,000 pixels.
- Aspect
Ratio: capable of displaying a
16:9 image at the minimum resolution level. Should your HD set be a 4:3 natural display,
the HD signal will be letter-boxed to a 16:9 aspect ratio, and the set manufacturer will
identify the number of active scan lines: 540 in progressive or 810 for interlaced
formats.
- Audio: receives, reproduces, and/or outputs Dolby
Digital audio.
- Tuner: receives all ATSC Table 3 formats and displays
them.
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Why Are
There Different Forms of DTV?
Networks and other
over-the-air broadcasters have a specific amount of broadcast capacity, or bandwidth, in
which to carry DTV signals. If a broadcaster wants to transmit the best picture quality
(HDTV) it will require most of its available broadcast channel capacity. A broadcaster
might choose the option to broadcast as many as 6 programs in the same channel at a lower
definition (SDTV), or a mix of HDTV and one or two SDTV programs.
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Why so
Many Formats Within DTV?
Analogue
broadcasting is a world without choices. Every analogue television uses 480 lines, the
same interlaced scanning at 30 frames (complete pictures) per second and the same 4:3
aspect ratio screen. This system is abbreviated as 480i or 480/30i.
In comparison, the
ATSC recommendations give broadcasters and viewers a world of choice. The signal for
transmission may be scanned either Interlaced (i) or Progressive (p). Interlaced scanning
means that each frame is sent as two “fields” – one with the odd-numbered
scanning lines (A) and the next with even-numbered lines (B), similar to current
TVs. In progressive scanning, all lines of the frame are scanned sequentially and sent as
a single frame. There’s also a choice of 24, 30 or 60 frames per second and a choice
of standard 4:3 or wide-screen 16:9 aspect ratio. In total there are 18 formats, each
suited to a specific purpose. |
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The
ATSC Table 3 Formats for HDTV and SDTV Transmission. How will my HDTV be able to display all these
formats?
Digital TV
broadcasts will be received and decoded by your DTV’s ATSC compliant built-in tuner
or set top box. Set manufacturers will design their TV’s so that they will either
up-convert or down-convert the broadcast signal to their TV’s “native”
display format, the format of the screen. As an example, Brand A may have decided that
their set will display HD broadcasts in 1080i-30. Therefore the set will include circuitry
that will convert any of the other 5 HD broadcast formats, (such as 720p-60) into the
set’s “native” display of 1080i-30p. Similarly, that same set manufacturer
may have selected 480p-60 as the “native” display for all 12 Standard Definition
broadcasts, and will use circuitry to up or down convert all SD broadcasts to that
display.
Remember, as you
select your HDTV, that there are 2 different, but related sets of terminology. DTV
broadcasts will fall under 2 classifications: High Definition (with 6 formats of
transmission), and Standard Definition, with 12 different broadcast formats. DTV reception
and display criteria have the same 6 formats for High Definition, and separate the other
12 formats into 2 subsets: Enhanced Definition for 480p,and Standard Definition at 480i.
Your HDTV will be able to display all digital TV broadcasts, converted to the sets native
display format, as designed by the manufacturer, with the use of it’s ATSC tuner or
set top box.
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How
will I Receive HDTV?
In the US, digital
TV initially arrived through over-the-air (OTA) (terrestrial) broadcasts in previously
unused portions of the VHF/UHF spectrum. Standard VHF/UHF antennas will provide reception.
In Canada, only 20% of homes receive terrestrial broadcasts in this manner, and this is
currently not an economically viable solution for Canadian broadcasters. As a result,
initial DTV offerings in Canada were introduced through Cable, and Direct to
Home (DTH) satellite distribution rather than over-the-air. However, CityTV has been
broadcasting in High Definition since 2003 and OTA HDTV is available in Montreal (CBC, RC,
TQS), Toronto (CITY, CBC, RC, OMNI) and Vancouver (CTV) Other broadcasters have their
digital licenses applications in place with the CRTC. Up to 27 channels of HDTV are
available on DTH and typically 10 - 20 channels on Cable. All Canadian DTV services will
have to follow Canadian Government procedures, policies, and CRTC regulations.
Different networks
may choose different formats. A network might go one way, and some of its affiliates may
go another. A single station might broadcast HD (1080 or 720 lines) for prime time and SD
(480) at other times. The format you receive will be determined by the content provider,
and the signal distributor. Regardless, your HDTV, or set top box, will be able to convert
and display any digital signal, and will automatically switch between the different
formats.
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Who is
broadcasting HDTV?
United States. The major
networks, ABC, CBS, NBC, PBS and Fox are broadcasting HD in prime time throughout the US, and currently over 95%
of U.S. homes now have access to HDTV signals. By October 2003 over 1000 US stations were
broadcasting DTV, although they must simulcast their programming in NTSC until 2006.
Canada. At this time (mid 2005)
HDTV broadcasts are available over-the-air in Montreal, Toronto and Vancouver. In
addition, in certain border cities, HDTV broadcasts from the adjacent US cities can be
received. The content from Canadian HDTV broadcasters is also available on Cable and DTH
in many markets. Contact your service provider for programming and availability
information. Digital
broadcasting license applications for the other broadcasters and networks are in process
before the CRTC and new HDTV stations are expected to be on-air shortly.
When Broadcasters Begin Transmitting HDTV
Signals, What Happens to Current Analogue Televisions?
Nothing. The
current analogue signals will be broadcast just as they are today until the transition to
DTV is complete which is not expected until after 2006 in the US, and has yet to be
determined in Canada, as explained below.
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How
Long will Conventional Analogue TV Signals Be Available?
Since the transition
to digital TV will take a long time to complete, you’ll be able to watch analogue
broadcasting for years. As a point of reference, it took 13 years for sales of color
televisions to surpass black-and-white sales. In comparison, digital television represents
a change of even greater complexity. The earliest that analogue stations may be allowed to
shut down in Canada has yet to be determined but it is likely to be beyond the year 2010.
Because analogue broadcasting will be with us for years, new HDTV receivers will also
receive and display analogue TV signals.
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Am I
Getting DTV from my “Digital“ Cable, Satellite, or MMDS Service Provider?
Yes, if the program
was recorded in digital form, transmitted in digital form, and received by your TV tuner
or set top box in digital form. Once the signal reaches this point, the capabilities of
your TV will determine how good a signal you ultimately see. We’re back to whether
your set can display signals in the SD, ED, or HD display formats. And, in the case of HD,
the original digital signal still has to meet the HD criteria. Currently, the two Canadian
satellite companies and many cable companies are providing up to 20 HDTV channels. The
majority of the other digital offerings fall into the SD classification, or the programs
may only be digital in the transmission process, having been converted from an analogue
source. For consumers to receive true HDTV signals, the programs must originate in a
digital format, and be digitally transmitted. And remember, a “digital”
set top box does not decode HD signals. You will need to get an HD set top box from your
service provider
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What
About the TV I Own Now and the Next TV I Buy?
When analogue
signals are no longer available will my analogue television become obsolete? No. Consumers will be able to continue watching
analogue broadcasts, cable, videocassettes, DVD and satellite as well as watch the new
HDTV broadcasts using a DTV-to-NTSC set-top box. The set-top box will deliver many of the
benefits of DTV broadcasting including HDTV programming, superior picture and clear sound.
However, an analogue television cannot display the full quality of High-Definition images
or sound.
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What Features are Important When Buying an HD Set?
Technological
progress never stops, but there are some key things to keep in mind. The picture quality,
and display type (LCD, CRT, Plasma, LCOS, DLP and others) will be a subjective
choice. We’d recommend that you look at a 16x9 aspect ratio, in a screen size
appropriate for your room. You may decide on a set with a built-in HD tuner, or a set
without that, which would be HD Ready, and then would require an HD set-top box to receive
and display HD. The other issue is connectivity and many manufacturers are adding digital
input connections (DVI and /or HDMI) to their product offerings. Either one is advisable
for future connectivity. The other element to consider is the CableCard feature, which is
being introduced slowly. In the future this will enable you to use a Cable Card,
(like a PCM-IA card), from your cable/satellite provider, instead of a set top box. All
good questions to ask your retailer about. As they say, technology never stops.
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When
Should I Buy an HDTV?
HDTV is
revolutionizing the TV industry in much the same way that CD’s changed the recorded
music business. The end result will be that you will enjoy significantly improved picture
and sound quality with HDTV, but the process of recording, delivering and displaying the
program is new. Virtually every TV set manufacturer is aggressively marketing HD-Ready or
HD sets with built-in ATSC digital tuners. And pricing on these sets has dropped
dramatically, as economies of scale unfold. Purchasing an HDTV, or an HD-Ready TV is now
no more expensive that regular projection sets were a couple of years ago. The advantage
of buying one of these sets now, is that it enables you to enjoy the finest visual and
audio experience available, when watching HDTV programming.
The programmer and
the signal provider will determine the kind of signal (SD or HD) you get.
The kind of
television you have will determine the quality of picture and sound (SD, ED, or HD) you
will enjoy.
So, the answer is… whenever you are ready
enjoy HDTV - the finest quality television content in the world. There is a lot of content
available right now, and more being created every day.
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