shan_n95 said:
MACHAN UBA HD TV GANA DANNAWADA..DANNAWANAM MATA PODI HELP EKAK ONE
High-definition television (HDTV) is a
digital television broadcasting system with higher
resolution than traditional television systems (standard-definition TV, or
SDTV). HDTV is digitally broadcast because
digital television (DTV) requires less
bandwidth if sufficient
video compression is used.
When the first high-definition television (HDTV) sets hit the market in 1998, movie buffs, sports fans and tech aficionados got pretty excited, and for good reason. Ads for the sets hinted at a television paradise with superior resolution and digital surround sound. With HDTV, you could also play movies in their original widescreen
format without the letterbox "black bars" that some people find annoying.
Analog, Digital and HDTV
For years, watching TV has involved analog signals and
cathode ray tube (CRT) sets. The signal is made of continually varying
radio waves that the TV translates into a picture and sound. An analog signal can reach a person's TV over the air, through a
cable or via
satellite. Digital signals, like the ones from
DVD players, are converted to analog when played on traditional TVs. (You can read about how the TV interprets the signal in
How Television Works.)
This system has worked pretty well for a long time, but it has some limitations:
- Conventional CRT sets display around 480 visible lines of pixels. Broadcasters have been sending signals that work well with this resolution for years, and they can't fit enough resolution to fill a huge television into the analog signal.
- Analog pictures are interlaced -- a CRT's electron gun paints only half the lines for each pass down the screen. On some TVs, interlacing makes the picture flicker.
- Converting video to analog format lowers its quality.
Photo courtesy Consumer Guide Products
Analog TVs like this one can't use digital signals without a
set-top converter.
United States broadcasting is currently changing to digital television (DTV). A digital signal transmits the information for video and sound as ones and zeros instead of as a wave. For over-the-air broadcasting, DTV will generally use the UHF portion of the
radio spectrum with a 6 MHz bandwidth, just like analog TV signals do.
DTV has several advantages:
- The picture, even when displayed on a small TV, is better quality.
- A digital signal can support a higher resolution, so the picture will still look good when shown on a larger TV screen.
- The video can be progressive rather than interlaced -- the screen shows the entire picture for every frame instead of every other line of pixels.
- TV stations can broadcast several signals using the same bandwidth. This is called multicasting.
- If broadcasters choose to, they can include interactive content or additional information with the DTV signal.
- It can support high-definition (HDTV) broadcasts.
DTV also has one really big disadvantage: Analog TVs can't decode and display digital signals. When analog broadcasting ends, you'll only be able to watch TV on your trusty old set if you have cable or satellite service transmitting analog signals or if you have a set-top digital converter.
This brings us to the first big misconception about HDTV. Some people believe that the United States is switching to HDTV -- that all they'll need for HDTV is a new TV and that they'll automatically have HDTV when analog service ends. Unfortunately, none of this is true.
HDTV is just one part of the DTV transition.
Equipment and Signal
When you've found an HDTV with a screen size, aspect ratio and native resolution you want, you'll need to make sure the equipment you already own will work with it. If you already have a
DVD player, a
DVR, game consoles or other equipment, make sure that they can connect to the TV directly or through an audio/visual receiver. Many HDTVs have High-Definition Multimedia Interface (HDMI) connections, which can transmit audio/visual signals to the TV without compression. In some cases, you can use adapters to make your equipment compatible with your set.
Once you've picked up your set and installed it in your home, you'll need to get a signal. To get a signal, you can use:
- An antenna - Depending on your location relative to the stations you want to watch, a set of rabbit ears might do, but you might need a rooftop or attic antenna. You can buy an antenna that's specially made for digital signals, but any reliable VHF/UHF antenna will work.
- Cable - Keep in mind that digital cable is not the same as HDTV. You'll need to check with your provider to determine which packages include HDTV stations. You'll also either need a set-top cable box or a CableCARD™ to allow your television to receive and decode the cable signal.
- Satellite service - As with cable, check with your provider to determine which plans and stations use HDTV signals. You may need a different satellite dish and tuner to receive HDTV signals via satellite.
HDTV source resolutions
If you read those three axioms closely, you'll see that source is everything with HDTV. Or, as some unknown wag once said, "Garbage in, garbage out." There are two main HD resolutions in use today by HD broadcasters and other sources: 1080i and 720p. One is not necessarily better than the other; 1080i has more lines and pixels, but 720p is a progressive-scan format that should deliver a smoother image that stays sharper during motion. Another format is also becoming better known: 1080p, which combines the superior resolution of 1080i with the progressive-scan smoothness of 720p. True 1080p content is extremely scarce, however, and none of the major networks have announced 1080p broadcasts. The term 1080p today appears mostly in reference to the displays' native resolution, not the source.
read more-
http://www.cnet.com/4520-7874_1-5137915-1.html?hhTest
