|
14 Mar 2008 02:10:56 | Gary Davis
What is HDTV? By Gary Davis
Dish-Network-Satellite-TV.ws
Webmasters: You may reprint this article in its entirety,
providing you leave the Byline and
About Author :
sections
intact, including the links to Dish Network
Satellite TV. High
Definition TeleVision
is what HDTV literally means. But high definition compared to
what? In order to answer this question, we need to know a bit
about the original analog TV system. Analog
TV 30 images per second (in Europe 25) are shown by
normal analog TV sets.
It does this by writing image lines horizontally, 525 lines in
one image (In Europe 625) on the screen. The number of pixels on
one line is about 500. This would be a definition of 500 pixels
per line by 525 (or 625) lines. Compared to modern computer
monitors this is really bad. Even the lowest resolutions
monitors have higher resolutions (640 x 480) than an analog
TV. HDTV - High Definition TeleVision
HDTV is high resolution Digital TeleVision (DTV) combined with
Dolby Digital Surround Sound (AC-3). There are 18 different
formats defined for Digital TV of which 6 are considered to be
HDTV:
Active Lines Per Picture Pixels Per Line Aspect Ratio Frame Rate
Scanning Approach
The
difference between Progressive and Interlaced is not difficult.
It has to do with how one image is built up. With interlaced
technology the odd lines are shown first and then the even lines
are shown. The lines are shown in this order: 1,3,5,….521, 523,
525, 2, 4, 6,…. 522, 524, 1, 3, etc. This means that every 1/60
of a second a half image is shown. This often results in
flickering, which can be tiring for the eyes. Progressive
technology manages to show a whole image every 1/60 of a second,
resulting in a much smoother picture. How Is HDTV
Better? Normal TV has a resolution of
about 210.000 pixels. An HDTV screen has
a resolution of upto 2.000.000 pixels, which gives up to 10
times more picture detail.
The aspect ration of normal TV is 4 x 3 (4/3 times wider
than high). An HDTV screen has an aspect ration of 16 x 9, which
is also known as wide screen.
Higher sound quality using Dolby Surround.
The Future of HDTV The FCC (Federal
Communications Committee) has mandated that all TV stations in
the USA have to be able to broadcast HDTV programs by the year
2006. The mandates of the FCC do not have an impact on just the
broadcast companies, but also on cable companies and
consumers. Broadcast companies have to invest on
new equipment like cameras, editing equipment, etc.
Cable companies have to convert all of their
equipment, including receivers at the homes of their clients.
Consumers may have to buy new equipment, like a
top-box to convert digital signals back to analog signals, or
even buy a whole new TV set.
HDTV is the future, and a really
big step forward. We once started with simple black and white
TV, then moved to color TV, and wide screen TV. But all those
systems were still based on the same signals as the original
black and white TV used. When color TV was introduced it was not
possible to force the complete population to throw away their
black and white TV-sets and buy a color TV set. Therefore a
color TV signal still needed to be understandable for a black
and white TV. This prohibited the improvement of picture quality
until the age of Digital TV. The need to satisfy older TV
sets no longer exists and the much higher quality HDTV is
available via Satellite TV Systems.
About the author:
Gary Davis is owner of Dish Network
Satellite TV, has several years experience in the Satellite
TV Industry and has written several articles on satellite TV.
|
