My speciality. Шепелева М.А - 23 стр.

few years earlier, because the greater the number of lines, the greater the picture
resolution (clarity). Nevertheless even RCA's comparatively advanced system
produced a very small picture that could not be transmitted more than twenty-five
miles and was subject to significant static caused by automobile ignitions and other
electrical fields. RCA president David Sarnoff announced plans to build an
experimental television station and produce a small number of receivers, but he
predicted that full-scale consumer service was still a long way off. Whether he
truly believed this or was trying to lull competitors into a false sense of security,
events progressed faster than Sarnoffs pronouncement suggested.
        The following year, the Philco Radio and Television Corporation held a
demonstration of their 345-line system. It featured an improved-contrast black-
and-white picture rather than the murky green-and-white that had heretofore been a
hallmark of electronic television.
         By 1937, there were no less than seventeen experimental television stations
operating in some fashion, and Sarnoffs earlier prediction seemed much too
conservative. New players, including CBS, Philco, and Zenith, were bringing their
own technical expertise to bear, and such competition intensified the pace of
development At the New York World's Fair in 1939, RCA cameras captured the
welcoming speech by President Franklin Delano Roosevelt on a 441-line system,
and the public was able to view the latest prototype receiver at the RCA pavilion.
RCA/NBC's New York station, W2XBS (later to become WNBC-TV) began
regularly scheduled public broadcasts of two full hours each week to the few
hundred receivers in existence. It looked like real broadcast television was about to
arrive.
        Seeking to avoid a repetition of radio's chaotic early years, the Federal
Communications Commission held hearings in 1940 to determine how to convert
television most efficiently from an experimental to a regular broadcast medium. A
new National Television System Committee, made up of a number of technical
experts, was constituted to set standards for video operations. The committee
subsequently selected a picture made up of 525 lines with the picture surface being
completely scanned by the cathode ray eye at a rate of 30 times (30 frames) per
second. The picture portion of the television transmission would be amplitude
modulated (AM). The sound would be generated by frequency modulation (FM)
means. These standards were officially adopted on April 30, 1941, and they remain
the cornerstone of the U.S. (NTSC) television system to this day.