GB348353A - Improvements in methods of phantomization for telephone circuits - Google Patents

Abstract

348,353. Phantom systems. MARINO, A., 6, Viale Mazzini, Rome. April 28, 1930, No. 13024. Convention date, April 27, 1929. Addition to 283,217, [Class 40 (iv), Telephones &c.]. [Class 40 (iv).] Comprises a number of modifications of the system of the parent Specification in which each channel employs all the line conductors. In the system shown in Fig. 3, each telephone set is arranged in series with a number of transformers, one for each line, and the lines are connected to a common point O. In another arrangement, Fig. 4 (not shown), the 8 lines are divided into the 28 possible pairs, 4 pairs being given to each of 7 stations. Each pair is bridged by a transformer winding, the primaries of the 4 of these transformers corresponding to a station being connected in series with the telephone set. Modifications of this system are shown in Figs. 5, 6, 7 in which the primaries are connected in various ways so that the telephone is bridged across two mid-points of the primary circuit instead of being in series with it. In each case use is made of centre-tapped chokes which offer high inductance to circulating currents, but none to the useful currents. Induction preventing. Fig. 8 shows the preferred arrangement of the conductors in the cable, each conductor crossing the other 3 in turn.