Patent GB-384671-A (GB)
Title: Improvements in or relating to electrical signalling systems
IPC: E01C19/34
Filed: 1931-06-09
Abstract: 384,671. Electric signalling systems. ASSOCIATED TELEPHONE & TELEGRAPH CO., 1033, West Van Buren Street, Chicago, U.S.A. June 9, 1931, No. 16829. Convention date, June 18, 1930. [Class 40 (i).] Relates to signalling systems, more particularly for transmitting information regarding the selling prices of stocks. The system is similar to that described in Specifications 358,889, 358,924, 358,984, 368,369, 370,499, 370,500, and 376,754, wherein the various stocks. are coded 'by the operation of various combinations of letter keys which control a plurality of registers, the letter registration being translated into a numerical basis to operate further registers. Price and range quotations appropriate to the stock are registered in further registers and signals are then transmitted under. the control of all the registers to effect at a plurality of receivers, the. selection and operation of the appropriate stock indicators. The system comprises the following modifications of the systems described in.the prior Specifications. (1) The impulse transmission of the stock and price digits is effected in either of the following ways. (a) Each register is adapted to mark a combination of leads which are associated with voice frequency thermionic oscillators so that the digits which are transmitted successively are translated into impulses of different combination frequencies transmitted over a single loop circuit. At a receiver, frequency responsive apparatus sorts out the signals and markings are thereby applied to corresponding combinations of leads to operate the receiver registers. (b) Instead of voice frequencies currents transmitted over a single loop direct current impulses may be transmitted over a plurality of line wires corresponding in number to the number of leads associated with the registers. The receivers are operated by. corresponding line relays operated directly or through thermionic valves. (2) As described in the prior Specifications the stock :quotations are dealt with by two operators but instead of the signals of each operator being transmitted over independent line circuits, provision is made whereby both operators may transmit over a single line circuit, the arrangement being such that an operator can only obtain the use of the line when it is idle. (3) A modified arrangement for setting up short price numbers also is provided. According to the number of pricedigits registered, a price range digit is transmitted which at the receiver renders inoperative those price registers not required for the registration of a short number. (4) The arrangements at the receiver for selecting a particular stock in accordance with the stock digits also are modified by the provision of a single stock relay, selected over a circuit prepared by groups of " hundreds " and " tens " relays. The system employing voice frequency current may be modified so that both operators may transmit simultaneously by providing additional oscillators for the second operator. Similarly simultaneous transmission may be effected with direct-current working the arrangement being such that combinations of positive impulses sent by one operator are interspersed with combinations of negative impulses transmitted by the other. In this arrangement each line wire may have at the receiver a pair of polarized relays or be connected to parallelly connected thermionic valves differently biased so as to be responsive to the positive and negative impulses. Stock letter and price digit registration. The manner in which the combination of letters representing a particular stock is registered and the arrangements for translating the letter code into one having a numerical basis is substantially similar to that described in the prior Specification 376,754. The stock code is registered in " hundreds," " tens " and units registers SH, ST, SU, Fig. 8. Moreover, the price digits are recorded in registers PH, PT, PU, PF. in a manner similar to that described in the above-mentioned Specification and after complete registration, the register set RS2 which is similar to that shown in detail in Figs. 6, 7, and 8, is placed under the control of the keying equipment in order that a second quotation may be registered while the first is being transmitted to the receiver. Impulse sending equipmeht. When the registers SH, ST, SU are set a circuit is prepared ior a relay 504 which is operated when the stock range register, relay 501 is operated. Relay 501 also associates all the registers with the impulsing equipment through relays 31 .. 39. Relay 504 effects release of the stock letter registers and associated equipment (not shown) and locks the range keys against operation to prevent operation of the range register SR in the equipment RS2 prior to the completion of signalling initiated by RS1. Relay 504 also operates relay 901, Fig. 9, which associates the impulsing equipment. with the leads of relays 1001 .. 1004, Fig. 10. Pairs of transmitters T<1>, T<2> and T<3>, T<4> are provided for each operator, the spare transmitters T<2>, T<4> being brought into use by keys, TK<1>, TK<2> when breakdown occurs in the main transmitters. The. transmitters are provided with relays 901 .. 904 to ensure that only one transmitter can be associated with the leads at a time. Relay 901 earths lead 806 to prepare locking circuits for the counting chain of relays 40 .. 62, and also closes the circuit of relay 40 over interrupter 12. Interrupter 12 operates at each make-and-break a pair of counting relays in order to associate the stock and price registers successively with the impulse leads. An interrupter 11 driven on the same shaft as interrupter 12 is adapted to transmit a combination of current impulses over the leads of relays 1001 .. 1004 and back contacts of the registers according to the setting of. each register. The first pair of counting relays is not associated with the registers but is provided only for effecting the transmission of a preliminary impulse to associate the appropriate receiver with the corresponding transmitter, For transmitters T<1>, T<2> the preliminary impulse is sent over lead A while that for transmitters T3, T<4> is sent over lead B. Each transmitter T<1> .. T<4> is provided with a pair of interrupters 11, 12 driven from a common motor and spare sets of interrupters such as 21, 22 driven by a second motor may be brought into use by a change-over key if necessary. The switching arrangements are such that after the stock digits are transmitted, the stock range as registered on SR is sent and followed by the price range and price digits respectively. The price range i.e. the number of price digits in a quotation is sent according to the marking of the leads PR which marking is determined by the number of price registers PH .. PF operated. When the relay 62 of the final counting pair (added to the sender equipment for the purpose of introducing a pause between successive quotations) is operated all the relays of the registers and sender are released and the locking circuit of the range keys is opened to free the keys for operation in association with register set RS2. Repeating impulses. The relays 1001 1004 responsive to the impulse combinations transmitted by each register, control thermionic oscillators OS1 .. OS4 adapted to generate different frequencies. The oscillators are operated by tuned reed couplers and are connected across resistances which are connected in series with an amplifier TSA and are normally shortcircuited by the relays 1001 .. 1004. The amplifier TSA supplies a plurality of line wires each of which may supply a group of brokers' offices. In the arrangement shown, the line Ll supplies receiving equipment in one office only, a terminal receiving amplifier TRA controlling through valves, reeds tuned to the transmitting frequencies and adapted to control relays 1021 .. 1024 which send impulses over corresponding leads A .. D to control the setting of the receiver registers. In this manner combinations of impulses characteristic of the setting of each transmitting register and sent over the leads A .. D, Figs.' 8 and 9, are repeated as impulses of different frequency combinations over the line L1 to the receiver where the impulses are again restored to their original form of impulses simultaneously sent over different leads. ' In a modification the impulses may be repeated in the form of direct-current impulses, each line circuit comprising four line wires connected to groups of four relays corresponding to the various receiving stations. Instead of operating the receiving relays directly they may be operated through thermionic amplifiers which normally maintain the relays operative but upon the receipt of negative impulses from the transmitting station allow the relays to de-energize and effect operation of the receiver registers. To eliminate the effect of inductive disturbance on the' line wires, the wires are earthed through resistances at the transmitter and receiver, the resistances at the receiver being tapped to supply the valves. When the relays such as 1001 .. 1004 control a plurality of sets of line wires resistances are also connected in the line circuits in order to prevent an earthed conductor drawing excessive currents and thereby rendering the other sets of line wires inoperative. Operation of receiving equipment. The preliminary impulse sent out over lead A or B according to the transmitter operated, is effective at the receiver to connect up either equipment RE1 shown in detail or RE2. Accordingly one or other of the relays 1101 or 1102, Fig. 11, is operated to connect the stock " hundreds '' relays to the leads A .. D. If it is desired to operate equipment RE1 relay 1101 is operated to connect up the stock relays SH. Registration of the stock digits then takes place on registers SH, ST, SU, transfer being effected by relays 1121, 1123, 1125. Similarly the stock range digit is register