Patent GB-454276-A (GB)
Title: Improvements relating to telegraph signalling apparatus
IPC: H04L5/22
Filed: 1935-04-04
Abstract: 454,276. Multiplex telegraphy ; interconnection of telegraph stations. BRUFORD, R., Electra House, Victoria Embankment, London. April 4, 1935, Nos. 10518/35 and 9688/36. [Class 40 (iii)] Messages transmitted at two or more different speeds over two or more multiplex channels or over two or more lines connected by a repeater are handled by the same apparatus. In the cable-code systems described, in which the. speeds are in the ratio 5 : 4, the line time is divided in accordance with the faster speed but every fifth impulse period is missed or wasted by the slower transmission. Multiplex telegraphy. Fig. 1 shows the apparatus associated with the dot input relays S1, M1, at the sending end for two channels in a multiplex system, similar apparatus (not shown), being provided for the dash relays S2, M2. Dots to be sent over the faster or master channel cause the armature 22 of relay M1 to discharge the condenser 23 through segments 19, brush 20, and winding 26 of the sending-on relay SOP1, whose armature 31 feeds the line L. The outgoing impulses are prolonged by the hold-on winding 32 in co-operation with brush 28 and segments 29. Dots in the lower or slave channel, on the other hand, cause the armature 1 of relay S1 to discharge condenser 2 through brush 5 and segments 6, and so to energize a relay 10 and charge a storing-condenser 15, which discharges through brush 20 and segments 18 at the speed of the master channel. But every fifth segment 6 will be swept by brush 5 during one of the no-current intervals by which the signal periods are separated from one another. This segment will therefore be wasted and in the signals sent to line L the slave channel will contain corresponding waste periods. The function of the relay 10 and condenser 15 is to eliminate errors of timing arising from non-coincidence in the operations of brush 5 and relay 1. At the receiving end, Fig. 3, the dot signals are applied by armature A1 through brush 41 to segments 42, 43, at the speed of the master channel, and charge the storing condensers 44, 45 for the master and slave channels respectively. Dots in the master channel are fed to the master receiving dot relay 49 through brushes 48, 51 and segments 47, 50. The impulses are prolonged by a hold-on winding 52. In the slave channel the impulses stored on condenser 45 are discharged through segments 55, brush 56 and winding 57 to control the slave dot-receiving armature 61, and the impulses are prolonged by a hold-on winding 60 and segments 58. The segments 55, 58 are spaced according to the speed of the slave channel, and the waste signal periods received in that channel are eliminated in consequence of the difference between the spacing of these segments and that of segments 43. The invention can be applied to a multiplex system in which cam-operated contacts are used instead of rotary distributers, Figs. 5, 6 (not shown). It can further be applied to a repeater, Figs. 8, 9 (not shown), for use at a station C, Fig. 7, which sometimes acts as receiving terminal to a fast section A, B, C, and sometimes repeats from the fast section into a slow section C, D. A transmitter, Fig. 6 (not shown), at station A and a repeater, Fig. 9 (not shown), at station C are constructed in accordance with the principle described above. Specification 378,090 is referred to.