Patent GB-329189-A (GB)
Title: Improvements relating to automatic telephone systems
IPC: H04M3/22
Filed: 1929-06-04
Abstract: 329,189. Siemens Bros. & Co., Ltd., and Christian, D. A. June 4, 1929. Automatic and semi-automatic exchange systems.-In an arrangement for the routine testing of apparatus at an unattended exchange under the control of an operator at a main exchange, pieces of apparatus found to be faulty and pieces not tested owing to their busy condition are given distinctive markings. When a cycle of tests has been completed, the tester sends a signal to the main exchange, to indicate whether all the apparatus has been found in order or otherwise, and further signals may be sent to indicate the number of pieces of apparatus faulty and/or not tested. A re-test may be made of the marked apparatus or only of the apparatus not previously tested. The unattended exchange may be provided with register-markers of the kind described in Specification 328,752 in which the main exchange operator by dialling a special first digit gets access to a switch which receives a second digit and connects an earthed winding of the impulse receiving relay to one of the wires 1-8. The terminals A, B, C and C<1> are connected to a junction in the manner shown in that Specification. The distinctive markings are applied by means of two sets of switches such as SA, SB controlled by assigners ASA, ASB. Testing operation. The operator at the main exchange dials the number required to set the register-marker switch on wire 1, whereupon starting relay RS in the routiner RT energizes and locks. The pieces of apparatus are engaged in turn over the switch AS and are subjected to a series of tests. If a fault is found, a relay is operated to close contacts rf1, rf2. Relay TP energizes and connects up magnet DSA to step the assigned switch SA into association with the faulty piece of apparatus, when relay TS pulls up and locks and at ts2 connects earth to the terminal of wiper 3 of the switch AS and to the wire c<1> to mark the piece of apparatus busy. Relay SO, which takes the place of the usual step-on key, operates to advance the switch AS and restore the routiner to normal, and magnet DMA operates to step the assigner ASA. If a busy piece of apparatus is encountered, the routiner waits for a predetermined time, and if the busy condition still remains, contacts rf1, rf3 are closed. Relay Tp<1> energizes and the switch SB is stepped into association with the busy piece of apparatus, which is marked by the connection of battery through relay R<1> (II) to the terminal of wiper 5 of the switch AS. Step-on relay SO operates as in the case of a fault being found. When the switch AS reaches its last position, relay F pulls up, disconnects relay RS and removes short-circuits from relays FT, FT<1> which operate over the locking circuits of relays TS, TS', and close parallel circuits for relay A. Signalling result of test. Relay A connects earth to relay TA which operates provided the junction is idle, and relay TB energizes in series with relay JS, not shown (see Figs. 1, 2 of Specification 328,752) and connects ringing current to the junction. When the operator replies, relay TR energizes and applies fault tone to indicate that all the apparatus is not in order. On setting the register-marker switch on wires 7, 8 she receives tones indicating the existence of faulty apparatus and untested apparatus respectively. By setting the switch on wire 5, relay NT is energized to connect the junction to a resistance Q, of which the sections are normally short-circuited by contacts ts7, ts<1>7 of the switches SA, SB, so that measurement of the resistance of the loop gives an indication of the number of pieces of apparatus marked. To make a re-test of the marked apparatus, the switch is set on wire 2 to energize, relays CO, RS, the former of which connects test relay T to wiper 4 of the switch AS, which then hunts for battery applied through relay R on R<1> (I). Relay R or R<1> energizes in series wih relay T and disconnects relay TS to remove the marking, which may be re-applied as in the original test if the piece of apparatus is still found to be faulty or busy. To test only the apparatus previously found busy, the switch is set on wire 3 to energize relay EO in addition to relays CO RS, thus connecting test relay T to wiper 5 of the switch AS, which then hunts for battery applied through relay R<1> (II). All the marking switches may be freed by setting the switch on wire 4 to energize RR. The operator may ascertain at any time that the test is in progress by setting the registermarker switch on wire 6, when a tone is obtained over a contact of relay TT operated in parallel with relay RS. Keys may be provided in the routiner for local control, and it may be arranged for the routiner tq be started by a clock contact at the unattended exchange.