Patent GB-273730-A (GB)
Title: Signalling systems
IPC: H04L5/18
Filed: 1927-06-29
Abstract: 273,730. Western Electric Co., Inc., (Assignees of Curtis, A. M.). June 30, 1926, [Convention date]. Addition to 239,745. Eliminating effects of disturbing currents; restoring or modifying imperfect signals; type-printing telegraphs; distributor systems.-The system claimed in the parent Specification is modified to enable short-circuiting of the amplifier to be effected at a plurality of points, such short-circuits being arranged for successive removal at predetermined intervals after the connection of the amplifier to the cable. The drawings show the application to a multiplex distributor system employing a valve amplifying arrangement similar to that described in Specification 248,822. Shaping and amplifying the received signals. A switch S operable by a magnet 5 is adapted to connect the cable A to the local transmission system through a contact 83 or to the local receiving system through a contact 95. The latter is connected to earth through a shunted condenser 121, a shaping network 106 and the primary of a transformer 105 of which the secondary is in the input circuit of the first amplifying valves 11 provided with a grid biasing battery 12. The valve output circuit is coupled by a resistance 19 and a condenser 20 to a shaping network 18 comprising condensers 22, 23, a resistance 24, and an auto-transformer 25, all adjustable. The auto-transformer is connected as shown to the grid of the second valve 13 which is biased from a battery 26. The output circuit is coupled by resistance 28 and a condenser 29 to a shaping network 27 comprising an inductance 30 shunted by a resistance 31 and in series with a condenser 32, and this network is connected as shown through a potentiometer 33 to the grid of the third valve 14 which is biased from a battery 34. The output circuit is coupled by a resistance 36 and a condenser 37 to a shaping network 35 shunted by a resistance 41 in series with a grid-biasing battery 42 for the fourth valve 15. This network is similar to the network 27 and is connected as shown to the input circuit of the valve 15. The plate circuits of the valves 11, 13, and 14 are supplied from a battery 21 and that of the valve 15 from a battery 43. The output circuit of the valve 15 includes relays 45, 47 in series each shunted by a variable resistance. Distributor connections. The distributor, Fig. 2, driven by a phonic motor 70, comprises segments 60 -- 64 controlling respectively the transmission, the reception, the operation of an ecapement 84, the synchronizing, and the operation of the transmitter 76 or printer 77 according to which of these is functioning due to the position of the switch S, Fig. 1. The durations of the alternate periods of transmission and reception are determined by a timing device F. During transmission the contacts of the automatic transmitter 76 are connected as shown to the cable A through the distributor segment 60, a cam-operated contact 89, and the contact 83 of the switch S. Transmission continues until the device F closes a contact f to supply an intermittent current through the distributor segment 62 to a magnet 81 controlling the escapement 84 on the switching cam shaft driven through a friction clutch 83 from a motor 82. As the cam shaft rotates through a half revolution the successive operations effected by the cams are (1) opening of contacts 89 and 80 and closure of contact 91, (2) opening of contact 100, (3) opening of contact 101, (4) opening of contact 102, (5) closure of contacts 90 and 119. Contacts 107, 113, and 114 are opened during transmission and closed during reception by the action of their respective cams. The opening of contact 89 disconnects the transmitter 76 from the cable A, and the opening of contact 80 disconnects the transmitter operating magnet 78 from the segment 63. The closure of contact 91 serves to energize the magnet 5 for operating the switch S, and during such operation the transmitter is earthed through contact 96 before disconnection at contact 83 and subsequent connection of the receiver at contact 95. The opening of contacts 100, 101, and 102 serves to de-energize in succession magnets 8, 9, and 10 to remove short circuits from the primary of transformer 105, the secondary of transformer 105, and the input to the network 18 respectively. The closure of contact 90 connects the output of relay 45 to the segment 61, and the closure of contact 119 completes the circuit through the printer magnet 79 and the segment 63. Synchronous movements.-The output circuit of relay 47 is closed through a relay 72 by the contact 107, and the armature of relay 72 supplies to the segment 64 the discharge currents of a condenser 110 charged from a battery 112. Alternate contacts 108 of segment 64 are connected through the right-hand winding of a relay 7, the back contact of a relay 74, and the contact 113 to earth. Operation of relays 73 closes, a circuit through the relay 74 and the contact 114, and the relay 74 operates ratchet mechanism 75 to apply the required phase, corrections to the distributor brushes.