Patent GB-220364-A (GB)
Title: Improvements relating to automatic telephone systems
IPC: H04Q3/00
Filed: 1923-05-12
Abstract: 220,364. Siemens Bros. & Co., Ltd., Dumjohn, F. P. W., and Humphries, H. E. May 12, 1923. Automatic and semi-automatic exchange. systems; metering.-In an inter-exchange system in which the exchanges are denoted by one or more code digits, by-path apparatus is operated by the code digits to select an idle junction to or in the direction of the wanted exchange, and a direct talking connection is then established between the selected junction and the calling line over switches operated by impulses transmitted from the by-path apparatus, after which the bypath apparatus is released. If the wanted exchange is reached indirectly through one or more intermediate exchanges, an impulse sending apparatus associated with the outgoing trunk selected by the last code digit generates additional routing-digits which direct the call through the intermediate exchanges. In the case of a call to an exchange reached directly from the originating exchange, the by-path is released as soon as the talking path is completed and any numerical digits not fully transmitted are completed over the talking path. In the case of a call to an indirectly-reached exchange, however, the numerical impulses are stored at the by-path apparatus and are retransmitted after the routing-digits have been sent out. The invention is described with reference to a system represented diagrammatically in Fig. 1. A calling line is connected non- numerically to a repeater-link 2 for which an idle two-coordinate link-seeker 7, preselected by an assigner 6, hunts. The repeater-links are arranged in divisions of one hundred, each linkseeker 7 being individual to a particular hundreds division. The exchange-code digits operate one or more two-coordinate selectors 8, 9, X (hereafter referred to as the A-, B-, and C- selectors), each selector responding to one digit only and then rotating automatically, the particular level selected by the final code selector giving access over a non-numerical junction-selector 10 to an idle outgoing junction in the required direction. If the code dialled denotes an indirectly-reached exchange, the trunk selected by the last code selector leads over a routing-digit sender 14. Associated with the outgoing end of the seized junction is a division selector 5 giving access over a non-numerical switch 4 to a link selector 3, the division and link selectors 5, 3 being operated by impulses transmitted from apparatus 12 in the by-path to select the calling link 2. The by-path apparatus below the horizontal dotted line is then released and conversation takes place over switches 3, 4, 5. The system also comprises apparatus 11 which, in the case of undue delay in dialling any digit, sends out impulses which direct the call to a monitoring attendant; metering-apparatus 13 for effecting one or more operations of the calling subscriber's meter, the number of operations being determined by the setting of the by-path apparatus, and metering in all cases only taking place after a predetermined interval from the reply of the called subscriber; modified repeater-links 15 - - 17 for dealing with incoming calls from a local manual board, a distant manual board, and an automatic satellite, respectively; means for preventing simultaneous double connections by the link-seekers; and means for giving a busy signal if all the trunks in any particular level of the switches 8, 9, X, 5 are found busy. The reference numerals used in Fig. 1 correspond to the Figures in which the detailed apparatus corresponding to each numeral appears, the diagram at the top of Fig. 1 showing the manner of arranging Figs. 2 - - 12. Figs. 15 - - 17 should be substituted in turn for Fig. 2. Preselection of idle link-seeker, Fig. 7, by assigner, Fig. 6. If all the link-seekers are busy, wipers ap, bp, c,p of the assigner rest in the position shown in Fig. 6, and relay AT, energized over wipers bp, cp and resistance w, holds open the circuit of driving-magnet DK. When a linkseeker, say that shown in Fig. 7, falls idle, relay AT is short-circuited over contacts k<1>3, l3 and magnet DK starts the switch to hunt for the idle link-seeker. As soon as wiper bp reaches lead 52, relay AT energizes over the circuit bp, 52, k<1>1, k<2>1, Fig. 8, rsx, Fig. 12, and winding 1 of relay L which does not energize, and the assigner is stopped. Operation of link seeker, Fig. 7, to connect calling link, Fig. 2, to the associated A-selector, Fig. 8. The operation of relay A at the repeater, Fig. 2, when a call is initiated, closes a circuit for relay V which, at its contacts v5, v3, respectively, marks the level and the contact in that level of the bank of the link-seeker which correspond to the calling repeater, and at its contact v4 closes a circuit D, j3, 53, at 2, ap, AF in which relay AF energizes and short-circuits its winding 2. Relay D then energizes and locks up over circuit d1, 54, ab 1. At the next closure of the circuit by interrupter 55, relay AQ energizes and locks over its winding 2 in series with wiper bp and winding 1 of relay L which now energizes, locks up over its winding 2, and connects its winding 3 to the vertical test wiper D‹. Relay L also locks up relay E<1> and completes a circuit over interrupter 51 and relay AM, for vertical magnet VM which raises the switch shaft until wiper D‹ reaches the marked level, when a circuit is completed for winding 3 of relay L which opposes winding 2 so that the relay releases. A circuit l2, cac, ta3, k<1>2, e'3 is now completed for rotary magnet RM which rotates the wipers until wiper C‹ reaches the marked contact when relay TA energizes in series with relay J and stops the rotation. The shortcircuiting of winding 2 of relay TA causes relay J to energize and lock up over its winding 2, thus marking the repeater busy. Relay TA lights lamp 57 and energizes relay TB which unlocks relay E' and extends the a- and b-leads to the A-selector, Fig. 8, where relay A<1> energizes in series with coil RA, Fig. 2, and energizes relay D<1> which applies dialling-tone 57a to the a-lead. Operation of A-selector in response to first code digit. The first set of impulses is repeated at armature a3 to relay A<1> and thence to the vertical magnet VM<1>. At the first vertical step, offnormal contacts k<2>3 transfer the circuit of the slow-release relay D<1> to back contacts a<1>1 of relay A<1> so that, at the end of the digit, relay D<1> releases and closes a circuit tc6, k<2>2, a<1>3 for the rotary magnet RM<1>. When an idle B-selector, Fig. 9, is reached, test relay TC energizes over wiper Ca and contact k<3>1, extends the a- and bleads and an additional x-lead to the wipers A<a>, Ba, X<a> and directly grounds wiper C<a> to mark the B-selector busy. Second and third code digits. The circuits for the operation of the B-selector, Fig. 9, and of the C-selector (not shown) in response to the second and third code digits are similar to those of the A-selector, the rotary motion of the C-selector resulting in the connection to an idle hunting- switch, Fig. 10. Selection of idle junction in required direction by non-numerical switch, Fig. 10. Relay R, energizing over the test wiper of the C-selector, first connects test relay T<2> to the test wiper Cd and then closes the circuit of stepping magnet DM. The switch is of the no-normal type, and when the wipers make contact with an idle junction 61 - - 64, Fig. 5, relay T<2> energizes, opens the stepping circuit, and by opening contact t<2>1 connects opposing windings 1, 2 of relay R in series with one another so that relay R de-energizes. Extension of connection to wanted line. If the junction leads to a distant automatic exchange, wires 63, 64 are strapped together and the incoming test circuit is over contact n5, wires 63, 64, off-normal contacts k<4>1 to battery. If the junction leads to local switches, wires 63, 64 are connected together in series with off-normal contacts of the first numerical selector. In either case, succeeding numerical impulses are transmitted over the by-path b-wire, contact n4, and lead 62 as long as the bypath is established. If the junction leads to a manual position, lead 64 is disconnected, whilst the extension of the b-lead operates a calling signal at the position. Establishment of talking- path; operation of division selector, Fig. 5, to select hundreds division containing the calling repeater-link, Fig. 2. Relay A<3>, Fig. 5, energizes over the x-lead, Figs. 10, 9, and 8, in series with relay J', Fig. 12, which closes a starting-circuit 66, v<1>3, cua, for magnet RSD of switch RS. When wiper rsa reaches its 3rd (from normal) contact, relay AA energizes over interrupter 67 and wipers rsa, cna, and operates V<1> which stops the switch RS and prepares a circuit for driving magnet CUD of counting-switch CU. The intermittent energization of relay AA causes the steppind round of switch CU and each operation of relay AA transmits an impulse to relay A<3>, Fig. 5, over contact aa<2>. Since the apparatus, Figs. 7, 8, and 12, is individual to a particular hundreds division, the number of impulses to be sent to the division selector is predetermined and the 3rd (from normal) contact of wiper rsb is permanently wired to, say, the 7th contact of wiper cub of the counting switch. Thus, when the required seven impulses have been sent out, relay B energizes over wipers cub, rsb, opens the circuit of relay AA to prevent further impulses, and closes a circuit over contact b1 for advancing switch CN one step. The continued de-energization of relay AA releases relay V<1> which completes a restoring- circuit over off-normal contacts for switch CU, and when wiper cua reaches normal a similar restoring-circuit for switch RS is closed over wiper rsd. At the division-selector, Fig. 5, the impulses received by relay A<3> are repeated to the vertical magnet VM<3>, after which the release of relay D<3> closes a circuit t<3>5, d<3>2, k<4>2, a