What is the Difference Between Digital TV and Analog TV?

The difference between Analog TV and Digital TV boils down to the way the TV signal is transmitted. Standard analog TV is transmitted in a manner similar to radio.

In fact, the video signal of analog television is transmitted in AM, while the audio is transmitted in FM. Analog TV is subject to interference, such as ghosting and snow, depending on the distance and geographical location of the TV receiving the signal.

In addition, the amount of bandwidth assigned to an analog TV channel restricts the resolution and overall quality of the image. The current analog TV signal standard (in the U.S.) is referred to as NTSC. NTSC is the U.S. standard that was adopted and came into popular use after World War II. NTSC is based on a 525-line, 60 fields/30 frames-per-second at 60Hz system for transmission and display of video images. This is an interlaced system in which each frame is scanned in two fields of 262 lines, which is then combined to display a frame of video with 525 scan lines.

This system works, but one drawback is that color TV broadcasting was not part of the equation when the system was approved. The implementation of color into the NTSC format has been a weakness of the system, thus the term for NTSC became known by many professionals as “Never Twice The Same Color”. Ever notice that color quality and consistency vary quite a bit between stations?

Digital TV, or DTV, on the other hand, is transmitted as data bits of information, just as computer data is written or the way music is written on a CD. In this way, the signal is basically “on” or “off”. In other words, the intent of DTV technology is that the viewer either sees an image or nothing at all. There is no gradual signal loss as the distance from the transmitter increases. If the viewer is too far from the transmitter or is in an undesirable location, there is nothing to see.

On the other hand, unlike analog TV, digital TV has been designed from the ground up to take all the main factors of the television signal into consideration: B/W, color, and audio, and can be transmitted as an interlaced (lines scanned in alternate fields) or progressive (lines scanned in a linear sequence) signal. As a result, there is greater integrity and flexibility of signal content.

In addition, since the DTV signal is made up of “bits”, the same bandwidth size that takes up a current analog TV signal, can accommodate not only a higher quality image in digital form, but the extra space not used for the TV signal can be used for additional video, audio, and text signals.

In other words, broadcasters can supply more features, such as surround sound, multiple language audio, text services, and more in the same space now occupied by a standard analog TV signal. However, there is one more advantage to the ability of a Digital TV channel’s space; the ability to transmit a High Definition (HDTV) signal.

Lastly, another difference between Digital TV and Analog TV is the ability to broadcast programming in a true widescreen (16×9) format. The shape of the picture more closely resembles the shape of a movie screen, which enables the viewer to see the movie as the filmmaker intended. In Sports, you can get more of the action in one camera shot, such as viewing the entire length of a football field without making look like it is a long distance away from the camera.

A 16×9 TV can display widescreen images without a large amount of picture space taken up by black bars on the top and bottom of a widescreen image, which is what you see if such images are shown on a standard TV. Even non-HDTV sources, such as DVD can also take advantage of a 16×9 TV.

Source: www.about.com