Patent GB-153136-A (GB)
Title: Improvements in electric telegraph systems
IPC: H04L27/24
Filed: 1919-08-27
Abstract: 153,136. Western Electric Co., (Western Electric Co.). Aug. 27, 1919. Multiplex telegraphs; transmitting systems and apparatus; type-printing telegraphs.-In a signalling system employing an uninterrupted alternating current, and in which signalling is effected by increasing the amplitude of certain half-waves, a wandering zero is prevented either by curbing certain augmented signal half-waves or by augmenting certain non-signal half-waves. The arm of a rotary distributor, operating in synchronism with the alternator, moves from one distributor segment to the next during the " no-current " periods of the current and remains in contact with a segment during a half-wave period. The arrangement may be applied to multiplex distributor systems. The transmitting system shown in Fig. 1 comprises five tape-controlled contacts 1, 21, 41, 61, and 81,.five intermediate relays 2, 22, 42, 62, and 82, five curbing-relays 6, 26, 46, 66, and 86, an alternator 18 connected to the line 13 by a transformer 15, 16, and a rotary distributor the brushes 38 and 39 of which are rotated synchronously with the alternator 18. The circuit of the alternator 18 is completed normally through a resistance 19 under which condition an alternating current of the amplitude shown at F, Fig. 2, is sent to line. The resistance 19 is adapted to be shortcircuited by the relays 2, 22, 42, 62, and 82 in order that an alternating current of the amplitude shown at G, Fig. 2, may be sent to the line; while under certain conditions the conjoint action of the relays 2, 22, 42, 62, and 82 and the relays 6, 26, 46, 66 and 86 insert resistances 9, 29, 49, 69, or 89 in parallel with the resistance 19 to curb predetermined augmented half-waves. If the tapecontrolled contacts 1, 41 and 81 be operated the relays 2, 42, and 82 are energized. The energization of the relay 2 short-circuits the resistance 19 over lead 35, contact 3, back-contact 7 of relay 6, segment 10, brush 38, ring 37, and lead 36 as the brush passes over the segment 10, thereby sending an augmented positive half-wave 74, Fig. 2, to the line 13. When the brush 38 engages the segment 30 a normal negative half-wave 74', Fig. 2, is sent to line since the relays 22 and 26 are not energized. When the brush 38 engages the segment 50 a curbed augmented positive half-wave 75' is sent to line since the operation of the right-hand armature of the relay 2 energizes the relay 46 from a battery 31 over lead 32, contact 5 of relay 2, contact 24 of relay 22, and lead 52, thereby causing the armature of relay 46 to engage its contact 48 and place the resistance 49 in parallel with the resistance 19 over lead 35, contact 43 of relay 42, contact 48 of relay 46, resistance 49, segment 50, brush 38, ring 37, and lead 36. Similar operations take place as the brush 38 passes over the segments 70 and 90, so that for this particular setting of the tape-actuated contacts an augmented positive half-wave, two curbed augmented positive halfwaves, and two normal negative halfwaves are sent to line. The brush 39 and contacts 55, 56 control the tape-feed magnets 53. In the modification shown in Fig. 3 the curbing-relays 6, 26, 46, 66, and 86 are each provided with two windings, the circuits of which are controlled by the intermediary relays 2, 22, 42, 62, and 82, the curbing-relays being arranged so that their armatures are operated only when both windings are energized. The energization of the relay 2 short-circuits the resistance 19 over the lead 35, contact 3, back contact 7 of relay 6, segment 10, brush 38, ring 37, and lead 36 as the brush passes over the segment 10, thereby sending an augmented positive half-wave to the line 13. When the brush 38 engages the segment 30 a normal negative half-wave is sent to line since the relay 22 is not energized. The energization of the relay 2 energizes over its contact 5 the left-hand winding of the relay 46, while the non-energization of the relay 22 energizes over its contact 24 the right-hand winding of the relay 46. The operation of the relays 42 and 46 places the resistance 49 in parallel with the resistance 19 during the passage of the brush 38 over the segment 50, thereby sending a curbed augmented positive halfwave to line. Similar operations take place as the brush 38 passes over the segments 70 and 90. In the modification shown in Fig. 4, the intermediate relays 12, 22, 32 and 42 operate in conjunction with the curbing-relays 16, 26, 36 and 46 to curb an augmented non-signalling half-wave which follows an augmented signalling half-wave. If the tape-controlled contact 30 be operated the relay 32 is energized to short-circuit a resistance 6 in series with the alternator 5 as the brush 51 passes over the segment 39, thereby sending an augmented positive half-wave 54<1>, Fig. 5, to line. The energization of the relay 32 closes at its contact 35 the circuit of the curbing-relay 46 so that as the brush 51 passes over the contact 49 a resistance 48 is connected in parallel with the resistance 6, thereby sending a curbed augmented negative half-wave 55, Fig. 5. In a multiplex system, the last of the intermediate relays, instead of controlling the first curb relay as shown in the various arrangements, controls the curb relay operating in conjunction the first segment of the next quadrant.