Recent developments in submarine cable design

This paper aims at collecting together in convenient form data connected with recent developments in submarine cable design; it is not claimed that the methods set out are original. Rapid progress has been made in the past few years, during which the inductively loaded telegraph cable has been introduced, and, although some theoretical papers have been published, there is very little matter dealing with the whole question of submarine cable design. This paper traces the gradual increases of speed which have been obtained referring to the CR law, speed constants, duplex balance, and the limitation of speeds through external disturbances, with methods of reducing the latter. Examples are quoted. The development of the inductively loaded cable consequent on the introduction of high-permeability nickel-iron alloys is discussed and formul¿ are given for the attenuation and other constants. The cases when abbreviated formulae can be used are considered and necessary allowances and corrections are discussed. The paper concludes with some notes on the testing of laid cables.