Standard-definition television

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SDTV redirects here. For Arizona State University's campus channel, see Sun Devil Television.

Standard-definition television or SDTV refers to television systems that have a resolution that meets standards but not considered high definition. The term is usually used in reference to digital television, in particular when broadcasting at the same (or similar) resolution as analog systems.

In ATSC, SDTV can be broadcast in 704 pixels × 480 lines with 16:9 aspect ratio (40:33 rectangular pixel), 704 pixels × 480 lines with 4:3 aspect ratio (10:11 rectangular pixel) or 640 pixels × 480 lines with 4:3 ratio (and square pixels). The refresh rate can be any of 24, 30 or 60 frames per second.

Digital SDTV in 4:3 aspect ratio has the same appearance as the regular analog TV (NTSC, PAL, PAL2, SECAM) minus the ghosting, snowy images and static noises. However, if the reception is poor, one may encounter various other artifacts such as blockiness and stuttering.

Standards that can broadcast digital SDTV include DVB, ATSC and ISDB. The latter two were originally developed for HDTV, but they have proved to be more often used for their ability to deliver multiple SD video and audio streams via multiplexing, than to use the entire bitstream for one HD channel.

With the advent of digital output, television transmission quality is becoming more sophisticated. Standard Definition television (SDTV) and High Definition television (HDTV) are two of the new formats. SDTV is a digital format that provides a high quality picture, very similar to that of digital versatile disk.

The quality of these new digital transmissions will become the standard for the future of broadcasting. SDTV is a lower resolution picture than HDTV. The images on SDTV will be of better quality than those of today's TV screens. They will also still have stereo sound.

The difference between SDTV and HDTV is that the signal on SDTV is more compressed than that of HDTV. As the digital signal is compressed, broadcasters can transmit five SDTV programs, whereas HDTV can only broadcast one. Multiple program broadcasting, called multicasting, was not previously available with analog transmissions. The picture definition of SDTV is also slightly lower than on HDTV.

SDTV will give a greater range of choice in the type of viewing material you will be able to access. Children's programs, documentaries, films, and public affairs -- the choice will be far greater than before. It will be the equivalent of digital satellite services such as the Dish Network or Direct TV.

Most of the normal TV sets used today cannot receive digital transmissions. You will need a DTV receiver in order to accept them. DTV receivers are available at the moment; they work by connecting your television to an output. However, they are of limited performance quality. You will be able to watch SDTV and HDTV programs, but they will not be true, High Definition picture quality.

All broadcasters are now required by the FCC to use the new digital system. In order to fully experience SDTV or HDTV, you will need to buy a new television set. High definition sets first appeared in 1998. These television sets were very expensive, much like when the first compact disc players appeared. The price has dropped significantly since then, as the diversity of televisions available has grown.

See also

• Digital television
• digital audio broadcasting
• DVB, ATSC, ISDB, SBTVD
• EDTV, HDTV
• MPEG

Digital video resolutions

Designation	Usage examples	Definition (lines)	Rate (Hz)
			Interlaced (fields)	Progressive (frames)
Low; MP@LL	LDTV, VCD	240; 288 (SIF)		24, 30; 25
Standard; MP@ML	SDTV, SVCD, DVD, DV	480 (NTSC, PAL-M)	60	24, 30
		576 (PAL, SECAM)	50	25
Enhanced	EDTV	480; 576		60; 50
High; MP@HL	HDTV, HD DVD, Blu-ray Disc, HDV	720		24, 30, 60; 25, 50
		1080	50, 60	24, 30; 25
Image:Common Video Resolutions.svg
This table illustrates total horizontal and vertical pixel resolution via box size. It does not accurately reflect the screen shape (aspect ratio) of these formats, which is either 4:3 or 16:9.

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Wikipedia information about Standard-definition television This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Standard-definition television". It may not have been reviewed by professional editors (see full disclaimer). Help contribute to Americola and edit this article.