Radio Teletypewriter AN/GRC-46 pt1-2 1963 US Army Training Film

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• published: 21 May 2012
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more at http://quickfound.net/links/military_news_and_links.html "DESIGN, CAPABILITIES AND OPERATION FOR CW, VOICE AND TELETYPEWRITER COMMUNICATIONS; OPERATOR MAINTENANCE; VARIOUS MODELS OF SET AND RELATED TELETYPEWRITER SETS AND EQUIPMENT." US Army Training Film TF11-3314 Public domain film from the National Archives, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied. The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and equalization (the resulting sound, though not perfect, is far less noisy than the original). Split with MKVmerge GUI (part of MKVToolNix), the same freeware (or Avidemux) can recombine the downloaded parts (in mp4 format): http://www.bunkus.org/videotools/mkvtoolnix/doc/mkvmerge-gui.html part 2: http://youtu.be/xVqgOjyg2Uc http://en.wikipedia.org/wiki/Radioteletype Radioteletype (RTTY) is a telecommunications system consisting originally of two or more electromechanical teleprinters in different locations, later superseded by personal computers (PCs) running software to emulate teleprinters, connected by radio rather than a wired link. The term radioteletype is used to describe: - either the entire family of systems connecting two or more teleprinters or PCs using software to emulate teleprinters, over radio, regardless of alphabet, link system or modulation, - or specifically the original radioteletype system, sometimes described as "Baudot". In some applications, notably military and government, radioteletype is known by the acronym RATT (Radio Automatic Teletype). Landline teleprinter operations began in 1849 when a circuit was put in service between Philadelphia and New York City. Émile Baudot designed a system using a five unit code in 1874 that is still in use today. Teleprinter system design was gradually improved until, at the beginning of World War II, it represented the principal distribution method used by the news services. Radioteletype evolved from these earlier landline teleprinter operations. The US Navy Department successfully tested printing telegraphy between an airplane and ground radio station in August 1922. Later that year, the Radio Corporation of America successfully tested printing telegraphy via their Chatham, MA radio station to the R.M.S. Majestic. An early implementation of the Radioteletype was the Watsongraph, named after Detroit inventor Glenn Watson in March 1931. Commercial RTTY systems were in active service between San Francisco and Honolulu as early as April 1932 and between San Francisco and New York City by 1934. The US Military used radioteletype in the 1930s and expanded this usage during World War II.. The Navy called radioteletype RATT (Radio Automatic Teletype) and the Army Signal Corps called radioteletype SCRT, an abbreviation of Single-Channel Radio Teletype. The Military used frequency shift keying technology and this technology proved very reliable even over long distances. From the 1980s, teleprinters were replaced by computers running teleprinter emulation software. Technical description of RTTY A radioteletype station consists of three distinct parts: The Teletype or teleprinter, the modem and the radio. The Teletype or teleprinter is an electromechanical or electronic device. The word "Teletype" was a trademark of the Teletype Corporation, so the terms "TTY", "RTTY","RATT" and "teleprinter" are usually used to describe a generic device without reference to a particular manufacturer. Electromechanical teleprinters were quite heavy, complex and noisy and they have been replaced with electronic units. The teleprinter includes a keyboard, which is the main means of entering text and a printer or visual display unit (VDU). An alternative input device is a perforated tape reader and, more recently, computer storage media (such as floppy disks). Alternative output devices are tape perforators and computer storage media... http://en.wikipedia.org/wiki/Teleprinter A teleprinter (teletypewriter, Teletype or TTY) is a electromechanical typewriter that can be used to communicate typed message... Teleprinters are now largely obsolete, though they are still widely used in the aviation industry (AFTN and airline teletype system), and variations called Telecommunications Devices for the Deaf (TDDs) are still used by the hearing impaired for typed communications over ordinary telephone lines. In computing teleprinters have been replaced by fully electronic computer terminals which usually use a display screen instead of a printer, though the term "TTY" is still occasionally used to refer to them, such as in Unix systems.