One method which can be employed to speed up long distance radio facsimile, if space circuit limitations prove to be a permanent handicap, is multi-channel operation. Considerable thought and study has been devoted to this method of control. So far, this work has been reduced to practise on commercial circuits.
The references which illustrate the trend of this work follow.
Ranger (U.S. Patent 1,740,834;I.R.E. Proc., Vol. 17, No. 9, pp.1564-1575, September, 1929,U.S. Patent 1,789,687; U.S. Patent 1,800,357; U.S: Patent 1,807,011; U.S. Patent 1,807,012; R.H. Ranger)
Hansell (U.S. Patent 1,751,584, C.W. Hansell)
Schroter (U.S. Patent 1,792,767; Hochf. Tech. U Eleck. Akus., Vol. 41, March, 1933, F.Schroter)
Eldred (U.S. Patent 1,870,989, B.E. Eldrer)
Schriever (U.S. Patent 2,089,667, O. Schriever)
(C) Marius Rensen