Frequency Standards

Widely spaced equipments require a relatively high order of drive accuracy. In practically all facsimile installations this requirement is met by a tuning fork standard. The international standart of drive accuracy, 1 part in 100,000, can easily be met over long periods of time by employing a fork standard control. Tuning fork standards are covered by the following references.

 

Dye (Proc. Roy. Soc., London, 103A, p.241, May, 1923, D.W. Dye)

Wood (Jour. Sci. Inst., Vol. 1, p. 335, August, 1934, A.B. Wood)

Norrman (I.R.E. Proc., Vol. 20, No. 11, November, 1932, E. Norrman)

Ranger (U.S. Patent 1,802,478, R.H. Ranger)

Artzt (U.S. Patent 2,113,365, M. Artzt)

 

If the drive accuracy of 1 part 100,000 is mainted at the scanner and the recorder, it is only necessary to frame when the picture is started. A lower order of drive accuracy requrires the transmission of some form of control over the circuit. The following citations illustrate this method of control.

 

Jacobson (U.S. Patent 1,710,223, Moses Jacobson)

Zworykin (I.R.E. Proc., Vol. 17, No. 3, March, 1929, V. Zworykin)

Brower (U.S. Patent 1,834,330, W.M. Brower)

Ranger (U.S. Patent 1,940,016, R.H. Ranger)

Nichols (U.S. Patent 2,111,153, H.J. Nichols)

Finch (U.S. Patent 2,069,061; U.S. Patent 1,985,654, W.G.H. Finch)

Morton (U.S. Patent 2,050,363, E.R. Morton)

Long (U.S. Patent 1,930,246, M.B. Long)

 

An excellent review of modern synchronizing methods is illustrated by:

 Schiweck (Zeits. F. Fernmeldetechnik, Vol. 13, pp. 10-14, January 21; pp.24-30, February 18, 1932, F. Schiweck).

(C) Marius Rensen

 

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