GB1438786A - Timedivision transmission systems - Google Patents

Abstract

1438786 Coaxial cable SOC ITALIANA TELECOMUNICAZIONI SIEMENS SpA 15 June 1973 [15 June 1972] 28646/73 Heading H1A [Also in Divisions H4 and H2] For the avoidance of crosstalk in a timedivision communication system, a telecommunications line includes a coaxial cable having an inner conductor CI comprising at least one element having a thickness of order of magnitude 8, i.e. the skin-effect penetration depth at the sampling frequency; a tubular outer conductor CE also having a thickness of order 8; a dielectric IA of strongly non-polar material, e.g. polyethylene or PTFE; and connections for outer circuits, each connection comprising a first conductor welded to the outer conductor and a second conductor connected to a conductive plug inserted through a hole in the dielectric and arc-welded to the inner conductor. The cable may be formed by winding conductive foils respectively around an insulative rod II and a dielectric tube IA and inserting the covered rod into the tube IA. Alternatively the rod II and the tube IA may be metallized by vacuum evaporation or chemical deposition, or the tube IA may be metallized on both its inner and outer surfaces and the rod II omitted. Metallized layers may be thickened by electrochemical means: for a sampling frequency of 0À6 MHz a thickness of order 90 Ám is suggested. As an alternative to a thin-walled tube, the inner conductor CI may comprise a set of twisted mutually-insulated wires each having a diameter of order # as defined above, e.g. Litz wire, such that each wire successively occupies every radial position in the conductor. Connections to outer circuits may be made by a conductive plug P, Fig. 6, inserted a clearance aperture in the outer conductor CE and a radial hole in the dielectric IA, and arcwelded to the inner conductor CI. Alternatively, if the whole surface of the dielectric IA including the bore of the hole has first been metallized, contact may be made between the side of plug P and the metallized bore of the hole. Reference has been directed by the Comptroller to Specification 1,282,715.