DTV Means Digital Television
Many users watch TV on an analog TV set with a 4 x 3 screen. As digital television enters more and more into the mainstream with wide-screen capability and higher sound and visual standards. Digital Television transforms television technology which allows broadcasters to offer television programming with movie quality picture and Cd quality sound. DTV technology transmits large amounts of data which can also be accessed by computer or on the television set.
DTV is the first enhancement of television since the National Television Standards Committee (NTSC) wrote guidelines for television transmission in the United States in 1941. RCA developed a color standard which NTSC adopted for its commercial broadcasting in 1953. The system of 1953 was improved over the years by newer and higher quality technology but the system didnt change. Digital Television is the current upgrade of television technology.
A pixel is a PICture ELement and it actually is the smallest resolvable square of an image. Each picture consists of 3 even smaller dots of the colors red, green and blue. Together these 3 dots can create all the colors the viewer sees TV. A pixel is small enough for a viewers eyes to think that they are 1 dot on the screen and even though each pixel in fact shows 3 different colors the eyes perceive them as 1 color. DTV improves the resolution of TV by putting more than 4 pixels in the same space that analog TV uses for 1 pixel. Also in Digital TV each pixel is exactly square. Analog TV uses a slightly higher than wide pixel which is why sometimes analog TV shows distortions of the image.
The resolution of an analog television screen is very low. The NTSC standard sets for 486 active lines where DTV is set for 1080 active lines. The number of pixels on each line is only 720 where Digital Television can go as far as 1920 pixels per line. This is a vast improvement upon standard analog television.
Widescreen As a result of TV the movie theaters had to come up with a solution to compete with TV at home. The viewing experience in the movie theater had to be better otherwise nobody would care anymore to go to a movie theater. They tried many things but the best working solution was a wider screen.
Because the way we see is a more rectangular wider view, a wider viewing area gives much more visual information than the squarer image of analog TV (ratio of 4 wide by 3 high). DTV and a more specific version of it, HDTV, uses a ratio of 16 wide by 9 high. This wider screen improves the viewing experience to match the format used in the movie theaters.
Sound Analog TV can handle 2 audio channels whereas DTV can handle 5 audio channels and thus gives the possibility to have a home theater with surround sound to create a movie experience in the home.#
Better picture and better sound are the obvious advantages of DTV, but why is the fact that it is digital also an advantage? Its true that the same result can be achieved with an analog system. For that the viewer doesnt need to go digital. Japanese HDTV for example is transmitted over an analog signal. But there are some other advantages to digital systems.
Digital Television provides more data than analog. The information transmitted doesnt deteriorate over distance. Analog signals lose quality over distance while a digital signal doesn’t lose any quality.
With a higher quality image and sound DTV uses much more data than analog TV. Broadcasters in the United States are not allowed to use more bandwidth for 1 channel, so they somehow have to squeeze the additional data into the same channel.
MPEG-2 is the compression software used to put this additional data onto the channel. Because the information is digital, the data can be compressed into much less bits. The receiver has to decompress and the original data is back. MPEG-2 can reduce the amount of bits by a factor of up to 55.
Consider that standard analog TV has a resolution of 378,000 pixels where Digital Television can go as high as 2,073,600 pixels. A compression factor of 55 is more than 10 times than required so MPEG-2 is more than enough to squeeze much more data into the available bandwidth of a standard analog TV channel. All DIRECT TV Programming comes with digital quality picture and sound.