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NTSC (National Television System Committee) is the analog television system used in the United States, Canada, Japan, Mexico, South Korea, Taiwan, and some other countries (see map). NTSC is also the name of the U.S. standardization body that adopted it.[1] The first black-and-white NTSC standard for broadcast was developed in 1941 and had no provision for color transmissions. The standard called for 525 lines of picture information in each frame, and 30 interlaced frames per second; the frame rate was later slightly adjusted for the color standard. Civilian development of commercial television was halted with the entry of the United States into the war. In 1953 a second standard was issued, which allowed color broadcasting to be compatible with the existing stock of black-and-white receivers, while maintaining the broadcast channel bandwidth already in use. This was an important commercial advantage over incompatible color systems that had also been proposed. NTSC was the first widely adopted broadcast color system. After over a half-century of use, the vast majority of over-the-air NTSC transmissions will be replaced with ATSC by February 17, 2009 in the United States, and August 31, 2011 in Canada. Various digital television systems have replaced the vacuum-tube era standard. The National Television System Committee was established in 1940 by the United States Federal Communications Commission (FCC) to resolve the conflicts that arose between companies over the introduction of a nationwide analog television system in the United States. In March 1941, the committee issued a technical standard for black-and-white television that built upon a 1936 recommendation made by the Radio Manufacturers Association (RMA). Technical advancements of the vestigial sideband technique allowed for the opportunity to increase the image resolution broadcast to consumer televisions. The NTSC compromised between RCA's desire to keep a 441–scan line standard (which was already being used by RCA's NBC TV network) and Philco's desire to increase the number of scan lines to between 605 and 800 A 525-line transmission standard was selected. Other technical standards in the final recommendation were a frame rate (image rate) of 30 frames per second consisting of two interlaced fields per frame (21 interlacing) at 262.5 lines per field or 60 fields per second, along with an aspect ratio of 43, and frequency modulation (FM) for the sound signal (which was quite new at the time). In January 1950 the Committee was reconstituted to standardize color television. In December 1953, it unanimously approved what is now called simply the NTSC color television standard (later defined as RS-170a). The updated standard retained full backwards compatibility ("compatible color") with older black-and-white television sets. Color information was added to the black-and-white image by adding a color subcarrier of 4.5 × 455/572 MHz (approximately 3.58 MHz) to the video signal. In order to minimize interference between the chrominance signal and FM sound carrier, the addition of the color subcarrier also required a slight reduction of the frame rate from 30 frames per second to 30/1.001 (very close to 29.97) frames per second, and changing the line frequency from 15,750 Hz to 15,734.26 Hz. The FCC had briefly approved a different color television standard, starting in October 1950, which was developed by CBS.[2] However, this standard was incompatible with black-and-white broadcasts. It used a rotating color wheel (a technique re-used in the first DLP projectors developed in the late 1980s), reduced the number of scan lines from 525 to 405, and increased the field rate from 60 to 144 (but had an effective frame rate of only 24 frames a second). Legal action by rival RCA kept commercial use of the system off the air until June 1951, and regular broadcasts only lasted a few months before manufacture of all color television sets was banned by the Office of Defense Mobilization (ODM) in October, ostensibly due to the Korean War.[3] CBS rescinded its system in March 1953,[4] and the FCC replaced it on December 17, 1953 with the NTSC color standard, which was cooperatively developed by several companies (including RCA and Philco).[5] The first publicly announced network TV broadcast of a program using the NTSC "compatible color" system was an episode of NBC's Kukla, Fran and Ollie on August 30, 1953, although it was viewable in color only at the network's headquarters.[6] The first nationwide view of NTSC color came on the following January 1 with the coast-to-coast broadcast of the Tournament of Roses Parade, viewable on prototype color receivers at special presentations across the country.
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