Patent GB-296131-A (GB)
Title: Improvements relating to cable telegraphy
IPC: H04L25/04
Filed: 1927-05-27
Abstract: 296,131. Beatty, W., E., (Bell Telephone Laboratories, Inc.). May 27, 1927. Restoring or modifying imperfect signals; distributor systems; type-printing telegraphs. - Single impulses lost in transmission owing to cable distortion are restored at the receiving end of a telegraph cable by vibrating relays controlled by a line winding R and by extra pairs 30 of segmental distributor-rings, the circuit of the line winding R being independent of the distributor. The signals sent out by the distant transmitter are shown at T, Fig. 2; the signal elements are of two polarities, and the cable is earthed after each element has been sent. The signals arriving at the receiving end over the cable 10 are amplified at 51, and re-shaped by the polarized relay 11. Fig. 1; the currents thus impressed on the winding R of the relay 17 are shown at R, Fig. 2; isolated elements such as t1, t2, have been suppressed by cable distortion, while two or more successive elements of the same sign. such as t3, t4, are fused into a continuous signal such as r. The winding V of the vibrator relay 17, and the auxiliary vibrator winding AV cooperate with the distributor 30 in such a way that so long as no effective signals are being received the armatures VI, AV1, are rocked in turn. The circuit of the winding V passes through alternate live segments of the distributor 30, so as to be intermittently made and broken by the brush 38; and through the armature AV1 of the companion magnet AV, so that the current V, Fig. 2, through the winding V is timed by the distributor 30, while its direction is determined by the armature AV1 so as to be always opposite to that of the preceding current AV through the winding AV. Similarly the latter current is controlled through the remaining live segments of the distributor 30 and through the armature V1 so that, provided that no signal is being received by the winding 18, the current AV through the winding AV is, as at av1, av2, in the same direction as the preceding current v1, v2, through the winding V. The armature AV1 also controls the current PR through the printer relay PR, and the, latter determines the polarity of the current PM distributed through the rings 40 to the printer magnets 41 - - 45. Thus the lost impulses tl, t2, are restored at pm1 pm2, to the printer magnets. When, however, two or more similar impulses such as t3, t4, have given rise to a long impulse such as r in the winding R, the latter overpowers the winding V so that any opposed current such as v4 fails to rock the armature VI, and the printer relay current pr determined by this armature imitates the current r in polarity, the signals t3, t4, being consequently reproduced by the printer-magnet current pm3, pm4. Meanwhile the current av4, which is also determined by the armature vl, imitates the polarity of r in preference to v4, and the phase of the sequence of interactions between the vibrator magnets V, AV, is consequently shifted as nequired. In the upper ring of the distributor pair 30 the live contacts are separated by narrow dead contacts to prevent short-circuits from taking place through the brushes. The group of distributor segments appropriate to the printer 41 - - 45 is followed by groups appropriate to other channels of the multiplex system.