television: Television Technology Innovations
The FCC established a stereo audio standard for television in 1984, and by the mid-1990s all major network programming was broadcast in stereo. In 1996 the FCC adopted a U.S. standard for an all-digital HDTV system, to be used by all commercial broadcast stations by mid-2002. Although it was hoped that the transition to digital broadcasting would be largely completed by 2006, less than a third of all stations had begun transmitting digital signals by the mid-2002 deadline. In 2005 the U.S. government mandated an end to digital broadcasting in Feb., 2009 (changed to June, 2009, shortly before the deadline in 2009). After the transition to digital broadcasting was completed, older analog sets required an external digital converter in order to be able to use broadcast programs.
The next great advance was the adoption of a high-definition television (HDTV) system. Non-experimental analog HDTV broadcasting began in Japan in 1991. The most noticeable difference between the previously existing system and the HDTV system is the aspect ratio of the picture. While the ratio of the width of the old standard TV picture to its height is 4:3, the HDTV system has a ratio of 16:9, about the same as the screen used in a typical motion-picture theater. HDTV also provides higher picture resolution and high quality audio. A total of 750 or 1,125 scanlines are embedded in the HDTV signal. Each frame of video consists of 720 or 1080 visible horizontally scanned lines, and the rest of the scanlines may carry the time code, vertical synchronization information, closed-captioning, and other information.
Television networks experimented with so-called three-dimensional (3D) or stereoscopic television during the late 20th and early 21st cent., using a variety of technologies to create an illusion of depth in the picture. In the early 2010s, however, networks, filmmakers, and television manufacturers developed more regular 3D programing, an increased number of 3D motion pictures, and a variety of 3D-capable television sets (most relying on special glasses that needed to be worn while viewing 3D programs and movies). Consumers, however, did not widely embrace 3D television, leading major television manufacturers to end the production of 3D sets by mid-decade.
Because the wide availability of television has raised concerns about the amount of time children spend watching television, as well as the increasingly violent and graphic sexual content of television programming, the FCC required television set manufacturers to install, starting in 1999,
V-Chip technology that allows parents to block the viewing of specific programs. That same year the television industry adopted a voluntary ratings system to indicate the content of each program.
Various interactive television systems now exist. Cable television systems use an interactive system for instant ordering of
pay-per-view programming or other on-demand viewing of programs. Cable systems also may poll their subscribers' equipment to compile information on program preferences, and interactive systems can be used for instant public-opinion polls or for home shopping. So-called smart televisions include an operating system and storage, and allow users to run computer applications (apps) that resemble those designed for smartphones. Standards have also been developed for the distribution of television programming via the Internet.
- Evolution of the Scanning Process
- Development of the Television Camera and Receiver
- Development of Color Television
- Broadcast, Cable, and Satellite Television Transmission
- Television Technology Innovations
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.
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