Patent GB-326563-A (GB)
Title: Improvements in or relating to call announcer arrangements for semi-automatic telephone systems
IPC: H04M3/64
Filed: 1928-12-20
Abstract: 326,563. Standard Telephones & Cables, Ltd., and Wright, E. P. G. Dec. 20, 1928. Semi-automatic exchange systems.-In a call announcer system arrangements are made to transmit the word " double " if two consecutive numbers are identical, to make a pause between the hundreds and tens digits, and if indirect routing is required, to route the call to a tandem exchange, announce that indirect routing is required and withhold transmission of the number until the second exchange replies. The speech currents are picked up from a gramophone record and are amplified before being transmitted to line, the gramophone being common to a plurality of registering mechanisms. Storing dialled digits. The selector repeater circuit shewn is tested over wire T and if free the calling circuit is extended over bye-pass circuit' BP as described in Specification 324,982. Relays A and B operate. Magnet R1 responds to the first series of impulses e5, b3, C, a.i) moving its wipers 1 - - 9. At the end of the train C releases completing a circuit for E (c2, 3rd wiper of R1, t6) which locks via e8 and at e3 completes a cir.- cuit for magnet. R2 to step its wipers over banks C.T.M. The terminals of bank 9 of R1 are connected to contacts of bank C and R2 searches to find the group marked in its bank c and then to find a free circuit in that group indicated by battery on T, when relay operates from the marking earth on C and the battery potential on T, breaking the circuit of R2 and energizing H. Relay H places marking earth on the bank contact T to mark the selected trunk busy. Meanwhile the next series of Impulses are repeated by A over wire 105 to switch R3, Fig 2. When the train is completed relay C relapses and earth on wiper 1 of R3 is connected over 102, 103 to wipers 2 - - 6 of that switch storing the digit on relays MA - - MD and completing, a circuit for relay ZA in series with the storage relays. Relay ZA operates after a slow-to-operate pause completing a circuit for R3 to step its wipers to position 12. (105, 0, 108, wiper 7 of R3). The hundreds digit is stored in similar way and R3 is then moved to position 23. If the thousands and hundreds digits are the same a circuit is completed from wiper 7 of R3 in this position to operate the relays MA - - MD not already operated. Similarly the tens and units digits are stored and relays DA - . DD are all operated if these two digits are identical. Connection to operator. When relay H operated a circuit was completed for magnet R1 and the switch R1 steps until the preselected finder extends earth on H over wiper 2 of R1 to operate relay T, breaking the signal testing circuit over wire T, connecting bye-pass wire BP- to the negative circuit of the finder and completing a circuit for magnet SR to connect the finder wipers to the junction sleected by R2. When this circuit is reached earth from wiper 9 of R1 is extended over wiper M of the finder to operate relay M bridging the left hand winding of relay I (Fig. 2) across the outgoing loop and operating relay L (Fig. 5) to light calling lamp C.L. Announcement of call. The operator plugs into the circuit, disconnecting the lamp and substituting relay N for relay L. When the key LK is thrown I (Fig. 2) operates preparing the circuit of relay SA which is connected over wires 213, 214 to brushes CM1, CM2 bearing on the continually revolving drum C (Fig. 3). The cams SC are earthed and consequently SA pulls up and holds up whilst either brush is in contact with its cam. When switch R3 reaches position 45 its driving circuit passes through a contact of SA and consequently the switch steps home from this position one step every time SA pulls up i.e. for every revolution of C. When position 48 is reached a circuit is completed from the second winding of relay I over wiper 8 of R3 through operated contacts of the first storage group to one of the amplifier circuits such as that in Fig. 4 connected to the pick-up units PV. The units 1 - - 10 are continuously picking up the numbers 1 - - 0, pick-up 11 picks up the word " double " and the relay I acts as a transformer to transmit the number to the operator. Position 49 of wiper 8 is connected to contacts (not shewn) of the C group relays and position 51 connects to the D group and to the home position through a contact of RA to the U group. In position 50 there is no connection and consequently a break is made between the hundreds and tens digit as in manual practice. Relay RA operates on the first operation of SA and locks up to wire 101. When relay SA operates in the, home position BS (Fig. 1) pulls up (107) switching the circuit through. AS operates releasing the annunciator circuit and switch R1 steps to normal over its wiper 3. When the subscribers hang up AS releases followed by BS and DS. Tandem call. If the call is to be tandemed through one manual office to a second, the contact representing the exchange required is connected on bank 9 of R1 to relay TA one of the contacts of which couples the marked level to that of the routing centre. The apparatus then function as before until switch R3 reaches position 45 when if TA is operated a circuit is completed to PU12 over 212 and " Tandem " or another indication of indirect routing is announced to the operator. The operator connects to the exchange required and restores her key LK; relay I relapses allowing TA to release. When the operator at the exchange required answers, Q (Fig. 5) pulls up shorting N and re-operating I to allow the numerical portion of the number to be announced. Junctions engaged. The switch R2 hunts continuously for a free circuit until R3 reaches position 34 when if H has not operated, a circuit is closed from Bank 7 of R3 to operate relay G connecting busy tone to the calling subscriber and homing switches R1 and R3. When the calling subscriber releases relays A and B relapse and the connection breaks down. Specification 326,564 also is referred to.