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A walkie-talkie (more formally known as a handheld transceiver, or HT) is a hand-held, portable, two-way radio transceiver. Its development during the Second World War has been variously credited to Donald L. Hings, radio engineer Alfred J. Gross, and engineering teams at Motorola. Similar designs were created for other armed men, and after the war, walkie-talkies spread to public safety and eventually commercial and jobsite work. Major characteristics include a half-duplex channel (only one radio transmits at a time, though any number can listen) and a "push-to-talk" (PTT) switch that starts transmission. Typical walkie-talkies resemble a telephone handset, possibly slightly larger but still a single unit, with an antenna mounted on the top of the unit. Where a phone's earpiece is only loud enough to be heard by the user, a walkie-talkie's built-in speaker can be heard by the user and those in the user's immediate vicinity. Hand-held transceivers may be used to communicate between each other, or to vehicle-mounted or base stations. == History == The first radio receiver/transmitter to be widely nicknamed "Walkie-Talkie" was the ''backpacked'' Motorola SCR-300, created by an engineering team in 1940 at the Galvin Manufacturing Company (fore-runner of Motorola). The team consisted of Dan Noble, who conceived of the design using frequency modulation, Henryk Magnuski who was the principal RF engineer, Marion Bond, Lloyd Morris, and Bill Vogel. Motorola also produced the hand-held AM SCR-536 radio during World War II, and it was called the "Handie-Talkie" (HT). The terms are often confused today, but the original walkie-talkie referred to the back mounted model, while the handie-talkie was the device which could be held entirely in the hand (but had vastly reduced performance). Both devices ran on vacuum tubes and used high voltage dry cell batteries. (Handie-Talkie became a trademark of Motorola, Inc. on May 22, 1951. The application was filed with the U.S. Patent and Trademark Office, and the trademark registration number is 71560123.) Radio engineer and developer of the Joan-Eleanor system Alfred J. Gross also worked on the early technology behind the walkie-talkie between 1934 and 1941, and is sometimes credited with inventing it.〔(【引用サイトリンク】title=Al Gross )〕 Also credited with the invention of the walkie-talkie is Canadian inventor Donald Hings who created a portable radio signaling system for his employer CM&S in 1937 which he called a "packset", but which later became known as the "walkie-talkie". In 2001, Hings was formally decorated for its significance to the war effort.〔http://www.telecomhall.ca/tour/inventors/2006/donald_l_hings/WalkieTalkie.pdf?sourceid=navclient&ie=UTF-8&rls=GGLJ,GGLJ:2006-10,GGLJ:en&q=Donald+L.+Hings+. THE VANCOUVER SUN, Friday August 17, 2001 ''Walkie-Talkie Inventor Receives Order of Canada''〕 Hing's model C-58 "Handy-Talkie" was in military service by 1942, the result of a secret R&D effort that began in 1940. Following World War II, Raytheon developed the SCR-536's military replacement, the AN/PRC-6. The AN/PRC-6 circuit uses 13 vacuum tubes (receiver and transmitter); a second set of 13 tubes is supplied with the unit as running spares. The unit is factory set with one crystal and may be changed to a different frequency in the field by replacing the crystal and re-tuning the unit. It uses a 24 inch whip antenna. There is an optional handset H-33C/PT that can be connected to the AN/PRC-6 by a 5-foot cable. A web sling is provided. In the mid-1970s the United States Marine Corps initiated an effort to develop a squad radio to replace the unsatisfactory helmet-mounted AN/PRR-9 receiver and receiver/transmitter hand-held AN/PRT-4 (both developed by the US Army). The AN/PRC-68 was first produced in 1976 by Magnavox, was issued to the Marines in the 1980s, and was adopted by the US Army as well. The abbreviation HT, derived from Motorola's "Handie Talkie" trademark, is commonly used to refer to portable handheld ham radios, with "walkie-talkie" often used as a layman's term or specifically to refer to a toy. Public safety or commercial users generally refer to their handhelds simply as "radios". Surplus Motorola Handie Talkies found their way into the hands of ham radio operators immediately following World War II. Motorola's public safety radios of the 1950s and 1960s, were loaned or donated to ham groups as part of the Civil Defense program. To avoid trademark infringement, other manufacturers use designations such as "Handheld Transceiver" or "Handie Transceiver" for their products. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Walkie-talkie」の詳細全文を読む スポンサード リンク
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