Digital Tv For Beginners
Good news digital TV is here!
What is so great about digital TV, you wonder?
Well, for one thing resolution is much improved. Currently, analog television provides up to 500 lines of resolution. The resolution of an analog TV is 720 x 486 for a total of 349,920 pixels. Digital TV especially high definition television provide resolution of up to 1920 x 1080 pixels. which gives total of 2,073,600 pixels. That means the resolution of high definition TV is 6 times greater than analog television. Also, the pixel in analog television resembles that of a tall building that is it is tall and rectangular. HDTV pixels are 4 times smaller which means you get 4 times more pixels in a given area and giving four times more resolution. That means you get sharper and clearer pictures.
High definition TV has a aspect ratio of 16:9 while analog TV has an aspect ratio of 4: 3. Our field of vision is more attuned to a wider view . We have a rectangular field of vision rather than a square one . That means our eyes see more of the left and right rather than the top and bottom. A wide screen image fills more of our field of vision and provide a better picture. Films and movies are also made closer to 16:9 ratio aspect so when these movies are shown on TV you wouldn't get your picture cut off or the annoying black strips on your TV set.
High definition television enables you to enjoy Dolby digital surround sound. That means you can have 5.1 channels of sound for your left ,center and right front speakers and two rear surround speakers and finally a sub-woofer. Isn't that great?
Conventional analog TV uses interlaced display which show images with 60 fields or 30 frames in a second. Each frame is broken into two fields consisting only of even or odd rows of 240 lines. The odd rows are shown first and the scanning process starts from left to right , then top to bottom . The whole process is now repeated for the even rows. The process creates artifacts such as visible scan lines and becomes more apparent as the size of the TV screen increases. The flickering which occurs also makes our eyes tired. Digital TVs support progressive scanning which draws 60 full frames in a second instead of only 60 half frames in a second. You get a smoother image with less flicker and scan lines are hardly noticeable.
Going digital means you have greater choices of programmes than before. Broadcasters can choose to broadcast standard definition television which permit multiple programming. Broadcasters are limited bandwidth to broadcast their channels. They make use of compression technologies called MPEG2 to remove unnecessary parts of a picture . Take an example of a beach scene where someone saunters across the beach. The only object that moves is the person. So data is being transmitted only for the movement of the person from left to right while the old data is used for the sky, the sea and the beach.
Remember your disappointment on seeing a NSTC TV screen with snowy images /ghostly images? This is because of broadcast signal is being blocked or the broadcasting station is too far. Well, you won't have this problem if you have a digital TV. Images are either picture perfect and you don't receive it at all. This is the nature of digital technology which is either 1 or 0.
In time to come, digital television would encompass the use of interactive television. Instead of just sitting in front of your television being a couch potato, it offers you opportunity to shop online, play games and enjoy other activities.
By Ian Tham
About the writer
The writer is the webmaster of digiteevee.com
which covers the use of technology in your daily life.