Standard-definition television facts for kids

Standard-Definition Television (SDTV) is a type of television system. It offers a clearer picture than older analog TVs. However, it's not as sharp as newer HDTV systems. When people talk about 'SDTV', they usually mean digital TV broadcasts. These broadcasts have a picture quality similar to or slightly better than old analog TV. Digital TV uses digital signals to send sound and video. This is different from analog TV, which uses analog signals.

How SDTV Broadcasts Work

SDTV signals are sent out in a few different ways. This is based on rules from a group called ATSC.

There are three main ways SDTV broadcasts can look:

• First, the screen can be wide, like a movie screen. This is called a 16:9 ratio. The picture has 704 by 480 tiny dots, called pixels.
• Second, the screen can be more square, like older TVs. This is a 4:3 ratio. The picture also has 704 by 480 pixels.
• Lastly, another 4:3 screen option has 640 by 480 pixels. This one has the lowest picture quality.

The first option gives the best picture. The second is next, and the last one is the least clear. The picture can also update quickly, showing 24, 30, or 60 pictures (frames) every second. This is similar to the quality you would see on a DVD.

SDTV is a digital system. This means it can show both old analog TV shows and even HDTV shows. Of course, the HDTV shows will be seen in standard definition, so they won't be as sharp.

Why SDTV Was Good

SDTV has a picture quality similar to old analog TVs. But SDTV pictures look much clearer and more vibrant. This is because SDTV has less "noise" or fuzziness. It also has better sound.

Because SDTV uses a digital broadcasting system, it can do many cool things. For example, it can show different things at once (like multitasking). It can also show an electronic program guide, which helps you see what's on TV. These extra features were not possible with old analog TVs.

Compared to HDTV, SDTV has a lower picture quality. However, HDTV shows were not very common when SDTV was popular. Also, SDTV was much cheaper than HDTV. This made it a great choice for many people.

Comparing TV Types

There are generally three main types of television systems: analog TV, SDTV, and HDTV.

• Price: Analog TV was the cheapest, then SDTV, and HDTV is the most expensive.
• Quality: Analog TV and SDTV have similar picture quality, but HDTV is much better.

Analog TVs could only work with analog signals. But both SDTV and HDTV can work with both analog and digital signals.

See also

In Spanish: Definición estándar para niños