longitudinal tape speed

SUBJECT AREA: Broadcasting, Electronics and information technology, Recording

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Poniatoff was educated at the University of Kazan, the Imperial College in Moscow, and the Technische Hochschule in Karlsruhe, gaining degrees in mechanical and electrical engineering. He was in Germany when the First World War broke out, but he managed to escape back to Russia, where he served as an Air Force pilot with the Imperial Russian Navy. During the Russian Revolution he was a pilot with the White Russian Forces, and escaped into China in 1920; there he found work as an assistant engineer in the Shanghai Power Company. In 1927 he immigrated to the USA, becoming a US citizen in 1932. He obtained a post in the research and development department of the General Electric Company in Schenectady, New York, and later at Dalmo Victor, San Carlos, California. During the Second World War he was involved in the development of airborne radar for the US Navy.

In 1944, taking his initials to form the title, Poniatoff founded the AMPEX Corporation to manufacture components for the airborne radar developed at General Electric, but in 1946 he turned to the production of audio tape recorders developed from the German wartime Telefunken Magnetophon machine (the first tape recorder in the truest sense). In this he was supported by the entertainer Bing Crosby, who needed high-quality replay facilities for broadcasting purposes, and in 1947 he was able to offer a professional-quality product and the business prospered.

With the rapid post-war boom in television broadcasting in the USA, a need soon arose for a video recorder to provide "time-shifting" of live TV programmes between the different US time zones. Many companies therefore endeavoured to produce a video tape recorder (VTR) using the same single-track, fixed-head, longitudinal-scan system used for audio, but the very much higher bandwidth required involved an unacceptably high tape-speed. AMPEX attempted to solve the problem by using twelve parallel tracks and a machine was demonstrated in 1952, but it proved unsatisfactory.

The development team, which included Charles Ginsburg and Ray Dolby, then devised a four-head transverse-scan system in which a quadruplex head rotating at 14,400 rpm was made to scan across the width of a 2 in. (5 cm) tape with a tape-to-head speed of the order of 160 ft/sec (about 110 mph; 49 m/sec or 176 km/h) but with a longitudinal tape speed of only 15 in./sec (0.38 m/sec). In this way, acceptable picture quality was obtained with an acceptable tape consumption. Following a public demonstration on 14 April 1956, commercial produc-tion of studio-quality machines began to revolutionize the production and distribution of TV programmes, and the perfecting of time-base correctors which could stabilize the signal timing to a few nanoseconds made colour VTRs a practical proposition. However, AMPEX did not rest on its laurels and in the face of emerging competition from helical scan machines, where the tracks are laid diagonally on the tape, the company was able to demonstrate its own helical machine in 1957. Another development was the Videofile system, in which 250,000 pages of facsimile could be recorded on a single tape, offering a new means of archiving information. By 1986, quadruplex VTRs were obsolete, but Poniatoff's role in making television recording possible deserves a place in history.

Poniatoff was President of AMPEX Corporation until 1955 and then became Chairman of the Board, a position he held until 1970.

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KF / GB-N

1) ошибка; погрешность

2) искажение

- overhead way machine

1) вид; тип; характер

2) мода, вид [форма, тип\] колебаний; вид [тип\] волн

3) способ; метод; принцип

4) режим ( работы)

5) вчт. состояние

6) швейн. мода