Patent GB-368369-A (GB)
Title: Improvements in or relating to electrical signalling systems
IPC: H04L12/18
Filed: 1930-12-01
Abstract: 368,369. Electric signalling systems. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. Dec. 1, 1930, No. 36193. Convention date, Dec. 11, 1929. Addition to 358,984. [Class 40 (i).] In a system of the type described in the parent Specification wherein information regarding the selling prices of various stocks is transmitted to indicator boards located at different stations the indicators are set under the control of common register senders provided at the receivers. This arrangement avoids the use of indicators having wipers which test for contacts marked by registers. As described in the parent Specification, any particular stock is represented by one, two, or three letter keys which when operated effect a registration on a group of registers, the registration being translated to a three-digit numerical basis and reregistered in a further group of registers. Price and range quotations appropriate to the stock are recorded in further registers and the registered indications are then transmitted to the receivers to effect selection and operation of the appropriate stock indicators. Each indication recorded on a register is transmitted as a four-impulse code signal, the impulses being alternately negative and positive and each impulse being strong or weak according to the setting of the register. The system described comprises the following modifications of the system described in the parent Specification. (1) An additional series of impulses is transmitted in accordance with the number of price registers operated. (2) Additional counting relays are associated with the impulse controlling interrupter at the transmitter to introduce a predetermined pause between the successive transmission of quotations. (3) Instead of employing contact - making relay repeaters at the receivers, a pair of thermionic valves is employed to repeat the transmitted impulses to the receiving apparatus. (4) A local impulse sender is provided in association with the registers at the receiver to effect the resetting to zero of the indicators and stepping thereof into new positions in accordance with the setting of the registers. (5) The registers at the receivers may be partly released to allow a subsequent quotation to be recorded while the local sending apparatus is operating the indicators in accordance with the first quotation. (1) As shown in Figs. 8, 8a, the groups of leads SH .. SR are marked in accordance with the particular stock and stock range signals transmitted and leads PH .. PF are marked in accordance with the price digits. When the transmitter interrupter 803 is brought into operation coded impulses of the stock and stock range are transmitted over the line 857 to the receivers. After transmission of the impulses corresponding to the stock range (SR) an impulse code indicative of the number of price registers operated as determined by the operation of relays to mark leads PR is then transmitted. After the transmission of the price range signal, the price digits determined by the groups of leads PH .. PF, are successively transmitted. The effect of the price range digits at the receiver is to operate the relays A .. D of the corresponding register PR, Fig. 11, in a manner characteristic of the signal and thus prepare the zeroizing circuits of the appropriate number of price indicators to facilitate re-setting of these indicators during the registration of the subsequent price digits in the registers PH .. PF, Fig. 11. (2) Transfer of the impulse controlling equip. ment to the successive groups of leads SH .. PF is effected by transfer relays 809 .. 826. The interrupter pulses relay 806 which transmits the impulses to line and simultaneously energizes and de-energizes relays 808, 807 in turn. These relays control the pairs of switching relays 809, 810, &c., and the arrangement is such that one relay of a pair is operated by the second impulse of the four impulse digit and the other by relay is operated at the end of the digit. After operation of the relay 826 relays 827..832 are operated by the interrupter 803 to introduce a fixed minimum time interval corresponding to the time of three additional digits between successive transmissions of complete quotations. No impulses however are transmitted over the line 857 since the line circuit is opened at the back contact of relay 826. (3) As described in the parent Specification the stocks are dealt with by two operators each having two transmitters such as T3, T4, Fig. 9, the latter of which acts as an auxiliary in case of breakdown of the former. Each operator controls a plurality of receivers arranged in pairs, each pair forming a complete indicator. The receivers are divided into groups such as RE1 .. RE8 each group being connected to a branch conductor 905 which is connected to the line wire 903 through a resistance 904 which in the event of a fault on the conductor 905 prevents disablement of the other groups of receivers connected in multiple to the same line. Resistances such as 906, 907, &c. are also connected between the receivers and the branch conductor to prevent disablement of all the receivers in a group in the event of a fault in one receiver. The receiving arrangements at each receiver comprise a pair of thermionic valves 1041, 1042, Fig. 10, the grids of which are connected to the incoming line. The battery 1070 connected to the filaments, provides by reason of the earthing of line 857 at resistance 860, Fig. 8, sufficient negative bias on the grid to prevent normal operation of relays 1002, 1003 and allow operation of relay 1001. The impulses transmitted over the line comprise voltage variations with respect to the earth potential at the transmitter and the arrangement is such that relay 1001 falls back in response to a heavy negative impulse whilst remaining unaffected by a light negative impulse, the relays 1002, 1003 being unaffected by negative impulses, and adapted to respond singly or together in accordance with light and heavy positive impulses. In this manner the impulse codes are repeated to the register sets shown in Figs. 10 and 11. A differential relay 1008 effects the transfer of the marking leads from register to register and also switches over the leads controlled by relays 1001, 1002, 1003 from marking leads A, B to leads C, D at the end of the first positive impulse of each digit. In a modification the valves 1041, 1042 are connected to line through a condenser in order to obviate disturbance due to changes of earth potential on the line. The grids are then connected to earth through a grid leak. (4) The appropriate stock register group is selected in a manner similar to that described in the parent Specification, viz. a relay is operated in accordance with the setting of the register SH, Fig. 10, to switch through the leads of the registers ST, SU to a cross-connecting frame and in accordance with the marking effect the operation of a pair of relays which connect up the particular group of stock indicators. This operation however is delayed until after registration of the price range digit in the register PR. Subsequent to the selection of the stock indicator group, a relay in the group YC, OP, HT, &c., Fig. 12a, is operated in accordance with the setting of the register SR to select the particular set of indicators corresponding to the stock range as determined by the range keys. Upon operation of register PR in accordance with the number of price digits transmitted, the operating circuits of the appropriate set of indicators are prepared over leads 1107 .. 1110. A local sender, Fig. 11a, is adapted to send impulses to restore and reset the indicators. When upon operation of register PR differential relay 1145 is operated, the circuit of the interrupter 1143 is completed to effect impulsing of relay 1146. Impulses are thus sent over the earthed leads 1107 .. 1110 to restore to zero only those indicators which are to be operated. When those indicators are restored, a cam on each indicator drum switches contact 1308 from earth to lead 1132, and further stepping is prevented. Simultaneously with transmission of the zeroizing impulses counting relays 1151, 1152, &c. are operated successively. The relays 1149, 1150 are operated in turn by the interrupter 1143, the relay 1149 upon energization operating the first relay of a counting pair, which relay is maintained energized to prevent operation of the second counting relay until after release of relay 1150 following termination of the second impulse. When the relays 1161, 1162 are operated simultaneously with the last two restoring impulses the operated counting chain is released and prepared for further operation. Operation of relay 1162 closes the initiating circuit of the indicators over lead 1132 and subsequent impulsing by the interrupter 1143, transmits impulses to re-set the corresponding indicators in accordance with the setting of the registers PH, PT, &c. To terminate setting the appropriate leads of the indicators are opened at contacts of relays 1163 .. 1166 which are operated over the contact bank LS of the counting relays at points in the impulse cycle determined by the registers PH &c. In this manner the indicators are stepped to indicate the new quotation. When all the " stop " relays are operated relay 1145 falls back to effect the release of registers PR, PH, &c. In the event of faulty operation of relays 1163 .. 1166, relay 1172 is operated to light the alarm lamp 1174 and bring about the release of relay 1145. (5) The speed of the impulse sender at the transmitter is such that the registers PH, PT, &c., Fig. 11, are set by the time the local sender, Fig. 11a, has transmitted the restoring impulses. At the end of the transmitted impulses relay 1007 relapses and effects restoration of the registers SH .. SR. This allows the partial registration of a further quotation before the indication of the pr