<P> Sony first demonstrated a wideband analog high - definition television system HDTV capable video camera, monitor and video tape recorder (VTR) in April 1981 at an international meeting of television engineers in Algiers . The HDVS range was launched in April 1984, with the HDC - 100 camera, HDV - 100 video recorder and HDS - 100 video switcher all working in the 1125 - line component video format with interlaced video and a 5: 3 aspect ratio . </P> <P> The first testing television station in Mexico signed on in 1935 . When KFMB - TV in San Diego signed on in 1949, Baja California became the first state to receive a commercial television station over the air . Within a year, the Mexican government would adopt the U.S. NTSC 525 - line B / W 60 - field - per - second system as the country's broadcast standard . In 1950, the first commercial television station within Mexico, XHTV in Mexico City, signed on the air, followed by XEW - TV in 1951 and XHGC in 1952 . Those three were not only the first television stations in the country, but also the flagship stations of Telesistema Mexicano, which was formed in 1955 . That year, Emilio Azcárraga Vidaurreta, who had signed on XEW - TV, entered into a partnership with Rómulo O'Farrill who had signed on XHTV, and Guillermo González Camarena, who had signed on XHGC . The earliest 3D television broadcasts in the world were broadcast over XHGC in 1954 . Color television was introduced in 1962, also over XHGC - TV . One of Telesistema Mexicano's earliest broadcasts as a network, over XEW - TV, on June 25, 1955, was the first international North American broadcast in the medium's history, and was jointly aired with NBC in the United States, where it aired as the premiere episode of Wide Wide World, and the Canadian Broadcasting Corporation . Except for a brief period between 1969--1973, nearly every commercial television station in Mexico, with exceptions in the border cities, was expected to affiliate with a subnetwork of Telesistema Mexicano or its successor, Televisa (formed by the 1973 merger of Telesistema Mexicano and Television Independiente de Mexico). This condition would not be relaxed for good until 1993, when Imevision was privatized to become TV Azteca . </P> <P> The Soviet Union began offering 30 - line electromechanical test broadcasts in Moscow on October 31, 1931, and a commercially manufactured television set in 1932 . </P> <P> First electronic television system on 180 lines at 25 fps was created in the beginning of 1935 in Leningrad (St. Petersburg). In September 1937 the experimental Leningrad TV Center (OLTC) was put in action . OLTC worked with 240 lines at 25 fps progressive scan . </P>

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