GB697429A - Improvements in or relating to single side-band carrier-wave telephony systems - Google Patents

Abstract

697,429. Multiplex systems. PHILIPS ELECTRICAL INDUSTRIES, Ltd. Sept. 25, 1951 [Sept. 28, 1950], No. 22397/51. Class 40 (iv). In a single-sideband carrier multiplex system, several speech channels are arranged in a basic group, several groups are formed into a basic super-group by means of group carriers, and several super - groups are then shifted in frequency by means of super-group carriers; the lowest frequency ot tne basic group is an integral multiple of half the bandwidth of the basic group, the central frequency of the basic super-group is an integral multiple of half the lowest group carrier frequency, and the frequency spacing between two adjacent super-groups is an integral multiple of half the band-width of a group. As shown, Fig. 1, six speech channels are arranged in a basic group 1 extending from 24 to 72 kc/s, the group bandwidth being 48 kc/s and the channel carrier frequencies being 24, 32, 40 ... 64 kc/s. Five such groups are then formed into a basic supergroup 2 extending from 312 to 552 kc/s with a central frequency of 432 kc/s, the group carrier frequencies being 288, 336 ... 480 kc/s. Supergroup carrier frequencies which are successive integral multiples of 288 kc/s, starting at 1152 kc/s, are used to shift the super-groups so that the spacing between two adjacent super-groups is 48 kc/s. One basic super-group is not displaced in frequency. All the required channel, group and super-group carrier frequencies are obtained from the lowest group carrier frequency 288 kc/s by division and multiplication, Fig. 2.