GB821631A - Improvements in supervisory arrangements for use in telecommunication systems - Google Patents

Abstract

821,631. Unattended repeater stations. BRITISH TELECOMMUNICATIONS RESEARCH Ltd. March 13, 1957 [March 20, 1956], No. 8693/56. Class 40 (4). In an arrangement for indicating to an attended station the nature of a fault and the station at which it occurs, a fault relay operates a contact, e.g. ra2, Fig. 1, which connects a wire L3 indicating the type of fault to a point on a closed loop L1, L2 comprised in a bridge circuit, which is then balanced manually or automatically by adjusting the slider of the potentiometer S, the position of balance indicating the identity of the unattended station. The balance of the bridge, which is of the Murray type, is unaffected by variations in temperature. Operation of a contact such as ra2 disconnects similar contacts in all succeeding stations and brings up a relay A (in a group A . . . D of such relays) to indicate the nature of the fault F.ig. 2 illustrates the detailed arrangements at the attended station. The operation of one of relays A . . . D brings up X to sound an alarm; and an appropriate one of lamps LA . . . LD is lit. The attendant operates the corresponding one of keys KA . . . KD which opens the circuit of all the other relays to prevent confusion should another fault occur. The switch S whose contacts are interconnected by resistances, not shown, is then set to balance the bridge. This switch may have an additional arm which closes contacts in circuits for lamps identifying the unattended station. The arrangement may be made automatic by causing the operation of any of the relays A . . . D to operate the corresponding contacts KA . . . KD, and also to connect up a stepping magnet for the switch S, the stepping circuit being interrupted by the restoration of a polarized relay connected in place of the galvanometer G. Furthermore, the switch S may be replaced by a stepped ring of gas discharge tubes arranged to short circuit progressively increasing or decreasing resistances. The selected station is then directly indicated by the glow of the appropriate tube. In the case of repeater stations for coaxial cables the wires L1 . . . L6 may be low grade circuits over interstitial conductors.