Patent GB-326234-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/58
Filed: 1928-12-07
Abstract: 326,234. Automatic Telephone Manufacturing Co., Ltd., Kessler, F., Deyes, H. S., and Scowcroft, J. Dec. 7, 1928. Automatic exchange systems. - In a network of small exchanges in which code translation is employed, the register-translating equipment is centralized at one exchange which is suitably situated geographically, and forms a separate unit at that exchange distinct from the local switching equipment. Fig. 10 shows a system including satellite exchanges S1, S2 and a main exchange T with register-translating and tandem equipment RT, the local switching equipment S3 thereat being similar to the equipment at the satellite exchanges S1, S2 and being similarly connected to the equipment RT. A calling subscriber A for example is connected over a line finder FS, a junction finder JS and a junction J1 to the main exchange where a register-controller R is associated with the connection over a register-finder RS. If the. call is to a subscriber B in another exchange, the exchange designation is translated into a routing-number, and the call is set up over a first code selector FCS, a junction J2 and an incoming connector BS1. If however the call is local to the exchange S1, no routing- number is necessary, and the numerical digits are sent back over the junction J1 to control the local connector LS, the junction then being released. In all cases a preliminary digit is sent back from the register-controller to set a zoneentering switch at the originating exchange. The numerical switches employed may be 25-point single-motion switches, the first digit at the connectors LS, BS being received on a relay counting chain which marks the first line of the appropriate group to which the wipers rotate automatically. The first code selectors such as FCS respond to a single impulse train from the register-controller consisting of any number of impulses up to 24 and then take one step automatically to the first trunk of the wanted group. The latter type of switch forms the stibject-matter of another Specification. The earlier Provisional Specification refers to slightly modified systems employing bi-directional numerical switches. Call between subscribers on different exchanges. Connection to register-controller and registration of wanted number. Line relay L energizes and connects up relay S over a wiper of the distributor DS to start the finder FS, which rotates until the calling line is reached, when switching relay K energizes in series with cut-off relay CO, relay L remaining operated over its lower winding. Feed relay A and release relay B pull up, providing a holding circuit for relay K and connecting up relay M. When relay S falls back. relay CS individual to the junction 20, 21 preselected by the allotter AS energizes and connects up magnet JDM to advance the associated switch JS into engagement with the link circuit 7, 8, when switching relay KA energizes and extends the connection to the first code selector FSC (Fig. 5)). Guard relay CH energizes and removes ground from the corresponding terminal of the distributor DS. Relay SL now energizes over wire 20 of the junction in series with relay DB, connecting up relay SB while relay SA energises in series with relays SI, SD. Relays DA. SLA energize over wire 21 of the junction, and relay CB pulls up. A starting circuit is closed over wire 48 and the allotter QS for relay DAS in the register-controller (Figs. 7, 8, 9), and magnet RDM operates to advance the under RS into engagement with the calling first code selector. Test and switching relay DAK energizes, connecting ground to wire 47 to energize relay SK, which connects relay SA to the loop across wires 41, 42 and disconnects relay SLA, but relay DA remains held over wire 34, relay DC being energized. Relays DDA, DDB, DBR pull up, extending back dialling tone from wire 170, and energizing vibrator DV. Dialled impulses are repeated by relay A at a2 to relay SL, at Sl1 to relay DDA, and thence at dda1 to a set of two-step counting relays DAD, DBD, DCD. Relays CA, DDC, DS, DCA are operated during the train. Assuming the first digit to be 3, relay DCD energizes- and grounds the first nine terminals of wiper 130e, so that magnet CDM steps the code switch CS(e) to the 10th position. Change-over relay DCA falls back, and the second impulse train controls magnet CDM directly. Relays DDC, DS fall back in turn at the end of each train, sending an impulse to magnet DDDM to advance the input control switch (dd) one step. The third and following digits are therefore received by magnets NAM, NBM, NCM, NDM. Code translation and transmission of impulses. After the second digit has been received, a circuit is closed over wiper 147dd for relay DPR to disconnect vibrator DV, which operates its contact-springs a pumber of times before coming to rest, and impulses are now sent over springs dv1 and wire 34 to relay DA, Fig. 1, and repeated to magnet MDM of the metering switch MS(m), relay CH being operated. Impulses are also sent at springs dv2 to magnet SSDM to advance the sending switch (s) until wiper 138s finds ground' on one of its terminals via wiper 133e as determined by the first digit of the appropriate routing number, whereupon relay DSZ pulls up, re-energizing vibrator DV and rendering its springs ineffective. A restoring circuit is closed for magnet SSDM, and relay DSA which energized at the first step falls back, releasing relay DSZ and delivering an impulse to magnet ODM to advance the output control switch (o) one step. Relay DC falls back and The circuit of relay SA is put under the control of springs dv1, and the second digit of the routing number is repeated to magnet SDM of the first code selector FCS(f), in series with relay SEA. Relay SE pulls up, and relay SO which is held during the impulse train at back contact sa1 falls back, whereupon magnet SDM and relay SE interact to step the selector in sea.rch of an idle trunk, the terminals of wipers 118f, 119f being strapped together except in the case of the last trunk of the group, and providing operating ground for relay SE. When an idle trunk is found, switching relay SH energizes, and the succeeding digits are transmitted over the outgoing trunk to operate the incoming connector at the desired exchange, as described in the final paragraph. After the last digit of the routing number, relay DSZ remains energized over wiper 137e, and magnet ODM operates over the same circuit to advance the output control switch (o) to position 6 in which the first numerical digit is sent. When all the digits have been sent, relay DCO energizes over wiper 132e, disconnecting relays SK, DDA and releasing the register-controller. Zone metering. The reply of the called party energizes polarized relav SD, which connects battery through relay SLB to wire 20, releasing relay DB. Relay M falls back, connecting up relay ST in series with common relay MA, Fig. 3. and relays MB, MW and vibrator MV energize, an impulse being sent over wire 31 to meter MT. Relay MB which is slow to energize disconnects relays MA, MW and vibrator MV, and springs mv1, mv2 continue to produce impulses. Twostep relay MX energizes fully when springs mv2 open, and a second metering impulse is sent when springs mv1 re-close. Two-step relay MY energizes in a similar way, and a third metering impulse is sent. Relay SP next energizes and relay ST releases, while magnet TDM receives impulses to step the timo switch TS(t). After three minutes, a warning tone is sent to the calling party over wiper 169t, and if the call continues, after a further half-minute, relay SP is released to repeat the metering operation. Metering can alternatively be effected by means of a series of cams corresponding to the various zones. Release. Relays A, B, K relapse, allowing relay KA to fall back and release the junction 20, 21. In the first code selector, relays SLA, SD, SL, SB, SH fall back, while relay SE energizes and interacts with magnet SDM to advance the first code selector to normal. All trunks busy. If the first code selector finds no idle trnuk, it stops on the last trunk of the group, and relay SG energizes over busy ground on wiper 119f and sends back busy one over wire 173. Non-existent exchange code dialled. The unused terminals of wiper 133e are wired to relay DR, which energizes over wiper 147dd when the input control switch is stepped to position 2 and shunts relay DDA in order to operate relay SM, which disconnects relay DDA to release the register-controller. Relays SA, SK fall back, and relay SA re-operates over a local circuit, sending an impulse to magnet SDM. Relay SG then energizes over wiper 120/ in series with relay SE (inoperative) and connects up NU tone over wire 175. Delay in dialling. Relays DTP, DR are energized in turn by time impulses over wire 176, and the operation is as described above, except that magnet SDM operates if necessary to step the first code selector round to position 2. Call between subscribers in the seme exchange. Assuming the first digit of the wanted number to be 3, this digit energizes relay DBD in the register-controller, and magnet CDM does not operate at this stage, but advances the code switch CS in response to the second digit. Since the junction 20, 21 leads to the exchange designated by these two digits, wipers 122r, 131e are standing in corresponding positions and relay DC energizes, preparing circuits for skip. ping the output control switch positions in which the routing number is sent. The first or metering digit is sent to the metering switch MS, whereupon relav DSZ pulls up and remains held over wiper 141o and contacts of relay DC, so that magnet SSDM advances the sending switch to normal. Magnet ODM advances the output control switch to position 3, and then operates over its interrupter contacts in parallel with relay DSZ until the position corresponding to the first numerical digit is reached. Impulses are now repeated over