Patent GB-328752-A (GB)
Title: Improvements relating to automatic and semi-automatic telephone systems
IPC: H04Q3/42
Filed: 1929-03-26
Abstract: 328,752. Siemens Bros. & Co., Ltd., and Peters, C. L. March 26, 1929. Automatic exchange, systems. - In a register marker system digits received by the register marker over a route common to both operators and subecribers perform different operations dependent on whether the call is received from a subscriber or from a manual board. In the system described, positions from which a subscriber would get number unobtainable tone are used by the operator for breaking in on trunk calls, checking whether faults occur on the system and for battery-charging purposes. The switch used as a connecting link to the register marker also acts as a sequence switch. General operation. A register marker is taken into use by the assigner, Fig. 3, and seizes over link CCF a free connector CC which hunts for the calling line. The link CCF has 3 positions for each connector. When the calling line is found CCF moves to its second position and dialled impulses can be received by the marker, which marks the called line over DT3, DU2-6 and wire 11. The connector then hunts for the marked line, and if it tests free, CCF moves into position 3 to connect ringing to the called party. When the called party replies the marker is freed. First party release is arranged. If a party line is required an additional digit sets switch DA and coded ringing is transmitted. The operator may be called by dialling 0, and PBX facilities are provided. The operator can enter an engaged circuit by dialling 0 followed by the directory number of a wanted line. The digit 9, normally a spare group, is used by the operator for finding whether faults exist on the equipment, whilst battery charging is started. by dialling " 95," is stopped by dialling " 97," and its continuance may be verified by connection to " 93." Normal operation : connection to register marker. When the subscriber calls, LA (Fig. 2) operates, completing a circuit for AS in the assigner AC, marking the line as calling in the bank of the call finder CF, and marking the line as busy in the connector bank CS (see Fig. 7). Relay AS completes a circuit for AA over its winding (1) which allows CC to operate [over (1)]. BB pulls up [over (1)] ] when CC energizes, leaving CC dependent on (II) which is connected to the register marker. If this register marker is busy CC relapses, energizing AA(II); but as this winding is in opposition to AA(1), the relay falls back, leaving BB dependent on CC. CC(I) energizes, connecting CC(II) to the register marker over the back contact of aa3, and if this is busv CC falls back, and the sequence is repeated until one of the markers becomes free. When a free circuit is tested ST operates in series with CC. Operation of call finder and register marker. Relay ST completes a circuit for DF to step CCF. When a free circuit is reached T operates over wiper 7, completing circuits for slow to operate relay Q, which with T enables DC to move the connector one step. An interrupter circuit is also completed over wiper 5 of CCF for DD to step the call finder CF, and when the calling circuit is reached TC(I) operates in series with CO (Fig. 2, locking over TC(II) in series with T. Relay LA (Fig. 2) releases and the speaking circuit is switched through to wipers 1 and 3 of CCF. Relay B operated when TC pulled up, connecting A to the calling loop, operating magnet DF and slow release relay D. A operates over the calling loop followed by V, which releases T and allows DF to release and step CCF on to the second bank contacts connected to the connector. Dial tone is connected to line from DS. The numbers 20 - - 69 are allotted, in the present example, to subscribers, and one of these numbers is dialled; the first digit is repeated by A to DT and the second to DO, and the wipers of these switches are stepped a corresponding number of steps. D releasing at the end of the second train completes a circuit for E over contacts of the similar relay E<1> of the other register marker (as shown in dotted lines in Fig. 6), and if the relay E of the other controller is operated, marking of the contact is prevented. When the line marked by the other controller has been found, E<1> releases, allowing E to operate, marking the wanted line over DT3 and one of the switches DU2-6. An interrupter circuit over CCF5 is completed for DC and the connector is stepped until wiper D reaches the marked contact when S(I) operates over CCF8, wire 11 and DT3, breaking the circuit of DC to stop the connector. Testing and completion of ringing or busy tone circuit. Relay P is connected to wiper C, and if the line is free, battery from the relay CO (Fig. 7) operates P, and when G releases, CCF is stepped into the third position, and E releases connecting ringing signal from RG over CCF8 and 5 to the called line and ringing tone over CCF1 to the calling subscriber. When the called subscriber replies, TR(I) operates, locking over TR(II) in series with Q(II). Battery is connected over CCF4 to wiper D of CF to meter the call and earth over CCF2 operates VV to switch the circuit through. Speaking current is supplied over YA and YY, which relays provide the holding circuit for VV. If the called line had not been free P would not have operated, and on the relapse of G a busy signal would have been connected from BS over CCF1 to the calling line. Release of register marker. The operation of VV causes TC to release, followed in succession by A, V, TR. Q, B, S, TP and SA. The digit switches DU and DT restore to normal by selfinterruption, and when DT is fully restored the circuit over DT5 is completed for ST to mark the marker available for further calls. Release of connection. Relay VV releases when either subscriber replaces his receiver, releasing both relays CO. If the second subscriber holds the circuit, PG holds up, marking the circuit as busy and connecting up a delayed alarm device PL. Call to party line. All party line subscribers have 3 figure numbers starting with 4, and the fourth bank contact of DT6 is connected to DU8, contacts of which, connected to party lines, are commoned and connected to R to prevent ring- ing until the appropriate code has been selected. Relay R operates at the end of the second train, completing a circuit for RD and an impulsing circuit for DA, substituting the code ringing generator for the ordinary generator, disconnecting the ringing tone circuit and the circuit for ring cut-off relay TR and opening the circuit of E. The third digit is repeated to DA, and as the switch moves off normal E operates over DA4, allowing the connector to hunt for the marked line. When the train is completed, and if the line called is free, DB is stepped over DA3 by an interrupter, and as its wipers 2 - - 6 step over the banks, RR is operated in accordance with the code set up on the switches DA2, DB2 - - 6, and similar ringing pulses are sent out to the called line, coded ringing tone being connected to the calling line from DS. When the whole code has been sent RT operates until DB is restored to normal and connects TR to the called line. RT then relapses and the code is again transmitted and the sequence repeated until TR operates, switching through and releasing the marker as before. Reverting party-line calls. The digit 7 is dialled and the caller operates a magneto generator, manipulating it to apply ringing current in accordance with the code required. In the exchange the digit is received by the register marker and RL operates over DT6 connecting resistance battery over CCF4 to wire d, Fig. 2, which is connected to an auxiliary equipment, not shown, peculiar to party lines. A relay in this equipment locks up, connecting earth to wire c to hold CO and PG and to mark the line as busy. Relay RL also releases B which releases the register marker as before. When both the parties have cleared the auxiliary relay releases, allowing CO and PG to relapse. Call to PBX group. The lines of a PBX group are connected together in the marker circuits and the circuits 11 of all the lines, except the last, are connected through a contact of PG as indicated, the last circuit being connected as shown by the dotted line. The first line of the group is dialled and the switch hunts for the marked line. On engaged lines the relay PG is up and the marking is not therefore extended to the test contact. The switch therefore moves on until a free circuit or the last line of the group is reached. The switch stops on the last line if all others are busy, and if this circuit, is not free, busy tone is returned. Call to spare number. Spare groups of 10 lines such as the 1 and 8 groups in this example are connected in DT6 to relay L(I), and spare lines in allotted groups have their c wires connected via wire 13 to L(II). If a spare group is dialled L(I) operates DT6, connecting NU tone to the calling line. If a spare line is called L(II) operates over CCF6 when the line is reached, connecting NU tone as before. Calls to manual operator at main exchange. The auxiliary equipment, Fig. 1, is connected between the junction circuit and the line circuit, Fig. 2. The lines are marked in the connector similarly to PBX lines, the switch hunting for a free line in the group. Relay JT is connected to bank contact 10 of DT6, and contact 10 of DT3 is connected to the connector bank over 12, or connected to one of the switches DU2 - - 6 dependent on whether one or more than one exchange can be called. When 0 is dialled DT steps ten steps and JT operates, and when G pulls up, E operates, marking the group. When a free junction is found S(I) operates, as do P, CO and JS. Metering the call is prevented at jt2. When the called party clears, JS releases, and during the slow release period of JR, Fig. 1, the current in the junction is reversed to give a clearing signal. If more than one junction group is accessible jt1 is strapped as shown dotted, reoperating D at the end of the first digit to prevent E functioning u