Patent GB-265657-A (GB)
Title: Improvements in or relating to telephone systems
IPC: H04Q3/00
Filed: 1925-10-13
Abstract: 265,657. Automatic Telephone Manufacturing Co., Ltd., and Ray, A. J. Oct. 13, 1925. Addition to 246,550. Automatic and semi-automatic exchange systems; metering.-In a system of the kind described in the parent Specification in which impulsing and talking battery is fed forward over the speaking leads in the direction of the called party, through one or more supervisory relays, a plurality of supervisory relays are connected to one speaking lead only in order that supervision may be effected over the speaking leads separately, rather than by an alteration of the resistance of the forward loop as in the prior Specification. The 'invention is described as applied to a system comprising both automatic and manual exchanges, full automatic and semiautomatic calls, and calls to an enquiry operator, being described in detail. Battery is fed forward from the selector repeaters used in automatic calls over a marginal and a non-marginal relay which are connected in series to one of the speaking wires during dialling and speaking. The response of the non-marginal relay alone is used to hold the connection under the control of an operator, whilst the response of both relays effect metering. In a semi-automatic call, the operator meters the call so that only one supervisory relay is required in the selector repeaters outgoing from her position to send back the answering supervisory signal. A supervisory lamp at a first selector gives an attendant a signal if the calling party omits to dial or if his line develops a fault, or if the called party hangs up and the calling party does not. Full automatic connection; first selector repeater, Fig. 1. On the response of the line relay 5, the release relay 8 lights a supervisory lamp 50, prepares the switch for operation as usual, and energizes a relay 21, which disconnects one side of the speaking condensers to improve the impulse repeating circuit. The switch responds to the first digit and selects an idle two-wire trunk 61, 62 to an incoming selector, Fig. 2, in well known manner. The response of the switching relay 42 extinguishes the lamp 50, opens the initial circuit of relay 21, and connects up the wipers 51, 52. In the case of a faulty calling loop or if the caller omits to dial, the lamp 50 continues to glow. Incoming selector, Fig. 2. The line relay 63 first energizes over the lower speaking wire in series with a retard 18, Fig. 1, and the subsequent response of the release relay 66 energizes a relay 77 which in addition to performing similar functions to the relay 21, Fig. 1, bridges the line relay 63 directly across the speaking conductors to hold it over a forward loop including the upper winding of a supervisory relay 28 and another supervisory relay 33 which are connected to the upper speaking wire at the first selector. Relays 28, 33 both respond, the former closing a locking circuit for relay 21 which has not had time to fall away. The switch responds in the usual manner to the next digit which is repeated to line relay 63 at armature 7 of the first selector line relay 5. The relay 13 is energized during this and subsequent impulse series to shortcircuit relays 28, 33 and retard 18 to improve the impulsing-repeating circuit, but closes an alternative holding circuit for relay 21. The response of the switching relay 98 in the incoming selector applies earth to the test wiper 106 for holding subsequent switches, and closes a forward loop through supervisory relays 84, 89 and retard 70 for the bridged line relay at the intermediate group selector. Intermediate group selector and connector. These are identical to the switches illustrated in Figs. 3 and 4 respectively of the parent Specification, the group selector being provided with a combined change-over and release relay, and the connector with a combined change-over and ring cut-off relay. Impulses are repeated to these switches by the line relays of the first and incoming selectors. Completion of connection, talking current, metering. If the wanted line is idle, the connector wipers are switched through, ringing current is applied, and the bridge over the connector line relay is opened as in the parent Specification. The supervisory relays 84, 89 at the incoming selector are thereby de-energized, the former unlocking relay 77, which switches through the talking connection, closes a holding circuit for the line relay 63 over the lower speaking wire, and opens the forward loop from the first selector, causing the relapse of the supervisory relays 28, 33, 21 at this switch in a similar manner: the connection is now in the supervisory condition. On the reply of the called party, the forward loop from the incoming selector is remade, and both relays 84, 89 pull up, the former locking over its lower winding, and shortcircuiting a resistance 108 so that battery is directly connected to the upper speaking wire over a retard 92. Both supervisory relays 28, 33 are now energized at the first selector, the relay 28 locking up and earthing wire 4 to meter the call. Talking current is supplied to the called party over retard 70 and relay 89 at the incoming selector. Release. This is effected when the calling party hangs up, the relapse of the line relays 5, 63 initiating the release of the first and incoming selectors, and the removal of the earth from the test wiper 106 releasing the subsequent switches. If the calling party does not hang up, when the called party restores his receiver relays 89, 33 relapse, but relay 28 remains held over its lower winding, and a circuit is closed for the attendant's lamp 50. Busy test, signal, and release. If the called line is engaged, the busy relay of the connector connects busy tone and intermittent battery through a high resistance to the upper speaking lead, whilst the forward loop from the incoming selector is opened as in the parent Specification, causing the connection to assume the supervisory condition as described in the last paragraph but one. Each time battery is applied to the upper speaking wire the presence of the resistance permits the response of relay 89 only, which connects battery through resistance 108 to conductor 61 preventing the response of supervisory relay 28 and the consequent metering of the call. Release occurs as in the last paragraph. All trunks busy. If any one of the selectors is moved to an eleventh-step rotary position, the switching relay is energized but as no maintaining circuit is closed for the supervisory relay such as 28 or 84, the relay 21 or 77 relapses and switches through the talking wires to allow a busy signal, connected up at cam springs, to be sent back. Call to inquiry operator's position, Fig. 5. Such a call is made over the tenth level of the first selector, Fig. 1. When the switching relay 42 energizes, no circuit is found for the supervisory relays 28, 33 over the upper speaking wire 201, but relay 203 responds over the lower conductor 202 connects up tell-tale ringing induction and lights a calling lamp 212. Relay 21 deenergizes when its circuit is opened at armature 46 and establishes supervisory conditions. On the operator plugging in, sleeve relays 206, 215 respond, the latter lighting supervisory lamp 217, and the former cutting off the lamp 212 and the tell-tale ringing, energizing relays 218, 220, and connecting battery over retard 213 and resistance 214 to the upper speaking wire 201. Supervisory relay 33, only, operates, and closes an alternative holding circuit for the release relay 8 to transfer release control to the operator. When the calling party hangs up, relays 203, 218 de-energize and the lamp 217 is relighted to signal the operator. Semi-automatic calls. These may be set up from an operator's position, Fig. 6, over a special selector-repeater very similar to the incoming selector, Fig. 2, but only provided with one supervisory relay 302, Fig. 7, since metering is effected by the operator. When the operator inserts her cord circuit plug P2 into the outgoing jack J2, a lamp 256 is lighted in series with a sleeve relay 257, which lights a busy lamp 259. A circuit is closed over the lower trunk conductor 261 for the selector line relay 271, which prepares the switch and causes the responce of a relay 283, which fulfils the same function as relay 77 of the incoming selector, Fig. 2, and bridges the line relay 271 across the trunk conductors 260, 261. The supervisory relay 254 in the cord circuit is at this time shortcircuited ever off-normal springs 308. The operator now throws the dialling key K. disconnecting relays 253, 254 substituting therefore direct earth at the upper springs and battery over the dial 252, and dials the wanted number, in response to which the selector, Fig. 7, and subsequent switches operate in the usual manner. When the connection is completely set up or a busy condition is encountered, the opening of the forward loop de-energizes relay 302 which opens the circuit of relay 283 to establish supervisory conditions. On the reply of the called party, relay 302 pulls up and connects battery over retard 305 to the upper conductor 260, and since the dialling key K has been restored relay 254 is energized and short-circuits the answering lamp 256. The called party may flash the operator's lamp by vibrating his switch-hook. If the wanted party is busy, or a busy condition is encountered in a selector, intermittent battery on the upper speaking wire will intermittently energize relays 302, 254 and flash the lamp 256.