GB486082A - Improvements in or relating to multi-channel carrier signalling systems - Google Patents

Abstract

486,082. Two-way transmission. SIEMENS & HALSKE AKT.-GES. Jan. 31, 1938, No. 3000. Convention date, Feb. 3, 1937. [Class 40 (iv)] In a multi-channel carrier system involving three or more stations and comprising four-wire lines with amplifiers, the lines of each station are interconnected at a central point through frequency-selective devices in order to allow two-way communication between each pair of stations on appropriate frequency bands. In Fig. 2a, the lines from three stations A, B, C are interconnected through suppressors Su, Sm, So suppressing the bands u, m, o each of which includes a third of the total number of channels. In this arrangement, all the channels are available in one direction between any pair of stations, but only those within a selected band are available in the other direction. In Fig. 2b, in which filters Fu, Fm, Fo, are employed, each pair of stations is allotted an appropriate band for transmission in both directions. In Fig. 4, the channels are divided into two bands h, l, and the interconnections are made through filters Fh, Fl. Channels l carry signals from A to B, B to C, and C to A, while channels h carry signals in the reverse directions. This arrangement may be extended to interconnect N stations by the use of N-1 frequency bands. The bands may if desired contain unequal numbers of channels.