Patent GB-791346-A (GB)
Title: Improvements in or relating to electrical signalling systems
Inventor: THREADGOLD RONALD
IPC: H04Q3/42
Filed: 1955-06-04
Abstract: 791,346. Automatic exchange systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd. May 14, 1956 [June 4, 1955], No. 16090/55. Class 40 (4). In an exchange in which a single translator TRANS (Fig. 1) serves a group of registers REG1 to REG 50, and has access to a group of senders SEN1 to SEN25, a register, say REG1 having received sufficient information to identify the destination of a call, seizes the translator which takes into use an idle sender, say SEN1, serving the appropriate junction group, and applies a code indication of the sender seized to one lead in each of the groups of leads ML,.NL which indication is stored in the calling register REG1; the translator then transfers the first translated digit to the sender SEN1, and the register and sender are then disconnected from the translator: each subsequent seizure of the translator by SEN1 for the transfer thereto of a subsequent digit causes the translator to apply code markings corresponding to the code indication of SEN1 to the groups of leads CL, DL extending to all the registers, the register REG1 having that indication stored therein being then connected to the translator as determined by the identity of the stored indication and the _ applied markings. In the arrangement shown the code indication consists of a positive potential applied to one lead in each of the groups ML, NL; and the code markings of a negative potential on one lead in each of the groups CL, DL; but more than two groups of leads may be used in each case if the number of senders requires it. The comparison equipment is shown in the Provisional drawing. A code indication on one of the first group of five leads ML causes the corresponding one of five tubes VK1 (of which only one is shown) in the first comparison element 1SA of the calling first register to fire, thus priming the corresponding one of five tubes VK2; the indication on a lead of intermediate groups and that on a lead NL causing similar operation in intermediate elements (not shown) and in the last element 1SN. When the translator is seized by a sender it operates one relay in each of the groups such as A to E and V to Z to apply the code markings corresponding to that sender to the groups of leads such as CL and DL, thus connecting negative potential to the cathodes of the corresponding tubes VK2 in all registers and firing such of these as are primed. When any tube VK2 fires, the negative pulse applied from its anode to the cathode of the tube VK3 of the comparison element concerned fires that tube VK3, thus charging C2 and priming the tube VK4 of that element. Only in the register which is storing the code indication corresponding to the markings applied to the leads such as CL, DL will the tubes VK4 of all the comparison elements be primed, in each of the other registers in use there will be one or more elements in which a tube VK4 is not primed. To select the required register a negative pulse is applied to the cathodes of all tubes VK4 in the first comparison elements over leads such as SH. In those registers in which it is primed the tube VK4 fires and applies a negative pulse to the cathode of the tube VK4 in the second element and so on until in general a non-primed tube VK4 is pulsed. In the register to be selected, however, all the VK4 tubes are primed and all will fire in sequence, the resulting potential change on lead CT of that register initiating the connection of that register to the translator. The comparison elements in all the registers are reset by the reduction of the H.T. supply to tubes VK3 and VK4 in all elements by a switching circuit (not shown), whereupon the fired tubes VK3 and VK4 are doused, after which the H.T. supply is restored. The H.T. supply to tubes VK1 is switched off within each register when that register has completed dealing with a call, and the fired tubes VK2 are doused when the code relays in the translator are released.