Patent GB-227510-A (GB)
Title: Improvements in or relating to automatic or semi-automatic telephone systems
IPC: H04Q3/00
Filed: 1923-10-13
Abstract: 227,510. Automatic Telephone Manufacturing Co., Ltd., Mercer, R., Paulett, W. H., and Tench, r. Oct. 13, 1923. Automatic and semi-automatic exchange systems; metering.-In a system employing loop dialling throughout, supervision is effected over the speaking conductors independently. The invention is described as applied to a multi-office system comprising both automatic and manual offices. In making a call to an automatic subscriber, the supervision consists of the sending of a busy signal, metering, and release control, whereas in a call made over a manual operator's position it comprises the sending of a busy signal, and the answering and release signals. A call from an automatic subscriber to a subscriber in another distant automatic exchange is made over a local selector repeater, Fig. 1, an incoming selector repeater, Fig. 2, an intermediate group selector, and a connector, Fig. 4. A call from a manual subscriber is extended from an operator's position, Fig. 6, over an incoming selector repeater, Fig. 7, a group selector and a connector, Fig. 4. The dialling loops between the local and incoming selector repeaters, and between the incoming selector repeaters and the group selectors, include the windings of relays such as 17, Fig. 1, and 65, Fig. 2, which are maintained energized during dialling and hold the switches in dialling condition. When a connection has been extended as far as possible, these relays relapse and bring about circuit changes whereby the dialling condition is replaced by a supervisory condition. In a full automatic connection, this change includes the substitution of the loop circuit of the line relay at the incoming selector repeater by a circuit over one speaking conductor only, over which release is controlled by the calling subscriber. In full automatic and semi-automatic distant connections, talking battery is supplied to the called party from the incoming selector repeater. No incoming selector is used in making a local call and talking battery is fed to both subscribers from the first selector. Connection may be extended to an enquiry operator's position, Fig. 5, over a local selector repeater, Fig. 1, an incoming selector repeater, Fig. 2, and a group selector. In such calls release control is transferred to the operator. Automatic working: selection of wanted line in a distant automatic exchange. A calling line is extended by a line switch to a local selector-repeater, Fig. 1, which in response to the first digit is stepped is known manner to the level in which terminate the trunks leading to the wanted exchange. During the transmission of these impulses, a relay 11 is energized in parallel with the vertical magnet 16, and closes a circuit for the upper winding of a relay 17, which on the cessation of impulses locks up over its lower winding to battery and earth at the normally-closed contacts controlled by armatures 28, 31 of the switching relay 27. The stepping relay 21 and the rotary magnet 24 interact in known manner to step the wipers on to a. trunk 51, 52. Fig. 2. leading to an idle incoming selector-repeater at the wanted exchange, the switching relay 27 on its response connecting the lower winding of the relay 17 across the seized trunk at the make-before-break contacts 28, 31. The line relay 53 is thereby energized and prepares the selector-repeater, Fig. 2, for the receipt of the second digit. the impulses of which are repeated at the armature 7 of the line relay 5 to the line relay 53. At armature 6 the usual circuit is completed for the. relay 11, which maintains the relay 17 energized, and directly connects the trunk conductors to improve the impulsing circuit. The incoming selector-repeater, Fig. 2, operates in the same manner as the local selector-repeater, Fig. 1, the doublewound relay 65 corresponding to the relay 17 energizing over its upper winding during impulsing and afterwards locking up over its lower winding across the trunk conductors. On the response of the switching relay 76, the relay 65 is connected across the selected trunk 95, 96 at the make-before-break contacts 77, 81, and the line relay of the second group selector is energized. The circuit of the line relay 53 is maintained over armature 66 of relay 65. The next impulse series is repeated by the line relays 5, 53 to the second selector which is of standard construction with -the exception that the switching re'ay is provided with make-before-break contacts in order that when switching through to the selected connector trunk 151, 153, Fig. 4, the circuit through the lower winding of the relay 65. Fig. 2, will not be interrupted. In response to the last two digits, impulses are repeated to the line relay 154 of the connector, Fig. 4, which operates in well-known manner to select the wanted line. Busy test. If the wanted party is busy, the test relav 170 locks to the release conductor 152, disconnects the upper winding of the line relay 154 and the lower winding of relay 65, and connects alternate busy tone and busy flash battery to the upper trunk conductor 151. When battery is first removed from the upper trunk conductor 151, the relay 65, Fig. 2, relapses, connects the supervisory relays 82, 88 to the upper trunk conductor, and opens the locking circuit of the relay 17, Fig. 1, which connects the supervisory relays 32, 36 to the upper conductors, and connects the retard 20 to the lower trunk conductor to maintain the line relay 53 energized. The circuits are now in the supervisory condition. When busy flash battery is again connected up, a circuit is completed over the resistance 193 and the upper trunk conductor for the lower winding of relay 82 and for relay 88, but owing to the resistance 193 only the relay 88 responds. Relay 88 shunts the lower winding of relay 82, and closes a circuit over retard 86, resistance 85, and the upper trunk conductor 51 for the lower winding of relay 32 and for relay 36. Owing to the inclusion of resistance 85, the relay 36 only operates in this circuit. The relays 88, 36 energize in this manner each time busy flash !battery is applied, but their operation is without effect at this time. The callng subscrber, hearing the busy tone, hangs up and release occurs as described subsequently. Similar busying arrangements may be provided in case a group selector is driven to an eleventh contact, owing to all the trunks of a group being busy. Ringing current. If the wanted line is free, the switching relay 174 energizes over test wiper 184, locks up over its lower winding, de-energizes the line relay 154 and completes the ringing circuit from the ringing generator RG over the upper winding of the ringing cut-off relay 189. The relapse of the line relay 154 is accompanied by the de-energization of relays 65, 17 and the connection of the supervisory relays 82, 88, 32, 36 to the upper trunk conductors, as described in the previous paragraph. When the called party replies, the ringing cut-off relay 189 is energized, disconnects ringing current, and connects the speaking leads through in the usual manner. Metering. On the response of the ringing cutoff relay 189, a circuit is completed over the retard coil 69, Fig. 2, the called party's loop, the upper trunk conductor, the lower winding of relay 82, and relay 88. Relays 82 and 88 both operate in this circuit, the former locking up over its upper winding and short-circuiting the resistance 85, and the latter shunting the lower winding of relay 82 to secure a balanced speaking circuit, and at armature 89 completing a circuit over the retard 86 and the upper trunk conductor 51 for the supervisory relays 32, 36. The relay 32 locks over armature 33, and at armature 35 closes a circuit for the calling subscriber's meter, whilst the relay 36 short-circuits the lower winding of relay 32 to improve the balance of the speaking circuit. Talking current. Feed current is supplied to the calling party over the line relay 5, Fig. 1, and to the called party over the retard 69, Fig. 2, and relav 88. Release. When the calling party hangs up, the line relay 5 and the release relay 8 relapse, the latter closing the usual circuit for the release magnet 46 of the local selector and the line relay opening the circuit over the lower conductor of the line relay 53, which initiates the release of the incoming selector, the second selector, and the connector, in well-known manner. Local connection. This is completed in substantiallv the same manner as a distant call with the exception that no incoming selectors are employed, and talking battery is fed to both subscribers from the first selector. Connection to enquiry operator. The calling subscriber is extended to such an operator's position. Fig. 5. over a local selector-repeater, Fig. 1, an incoming selector repeater, Fig. 2, and a second group selector. All these switches operate as before, and when the connection is switched through to the trunk conductors 201 202, Fig. 5, the lower winding of the relay 65 is bridged across them, and a circuit is completed through a relay 204 and a retard 207. The relay 204 locks up, lights the supervisory lamp 215, and de-energizes the relay 65, which brings the apparatus to the supervisory condition as previously described. The operator plugs in, energizing a sleeve relay 208, which extinguishes the lamp 215, completes a circuit for relays 88, 82, Fig. 2, over the retard 207, a resistance 213, and the upper conductors 201, connects an impedance 214 across the jack springs, and transfers the locking circuit of the relay 204 to the lower lead 202 and the retard 69, Fig. 2. Owing to the inclusion of the resistance 213, only the relay 88 energizes, closing at armature 91 a holding circuit for the release relay 56, and completing a circuit for relays 32. 36, Fig. 1, over resistance 85. Relay 36 responds only, and holds the release relay 8 over armature 38. Release is thus transfe