GB1270737A - Repeater monitoring device - Google Patents

Abstract

1,270,737. Supervising repeaters. C.I.T.- COMPAGNIE INDUSTRIELLE DES TELECOMMUNICATIONS. 6 Aug., 1970, No. 38014/70. Heading H4R. In a transmission system comprising a transmission cable incorporating a number of parallel four wire lines and repeater units at spaced intervals along the cable, each repeater unit including a repeater for each line, and each repeater including go and return portions and means to interconnect these portions to loop the line for monitoring purposes, a repeater to be so looped is selected by co-ordinate selection techniques using a signal over an auxiliary conductor pair for unit selection and a signal over the appropriate line to select the individual repeater at that unit. The figure shows a single repeater 11 connected to a line 1, the signalling conductors PR and QY, a repeater unit selector WA and a repeater selector T. The repeater unit selects are each as shown in the broken line rectangle and include a relay 19 with contacts r and s normally in the position shown and a polarized relay 20 which depending on the polarity applied between conductors sets its contacts t and u in one or other of their changeover positions and leaves them in this state when de-energized. The contact positions shown correspond to a path looped condition in which positive potential has just been applied on conductor PR and negative potential on conductor QY. Relays 19 and 20 operate in turn changing over the state of all contacts to obtain a stable state with relays 19 and 20 enabled over a path including contacts r and t. While relay 19 is enabled a set of contacts a 1 to a 4 individually associated with the repeaters of that unit are closed. In the repeater selector T individual to the selected repeater a detector 15 responds to interrupton of a selection signal received over its repeater and via an inverter 16 enables a relay 17. A relay 18 associated with the selected repeater is enabled over contacts p and a 1 , a 2 , a 3 or a 4 and closes contacts a 1 to loop the two halves 11a and 11b of the repeater 11 via a loop length simulator 10. Relay 18 also closes self holding contacts 9. To break the loop the polarity of the lines PR and QY is reversed. Maintaining the original polarity but interrupting it releases relay 19 after relays 19 and 20 have operated establishing a direct path between P and R via contacts r and t, the loop between P and Q being broken. Thus the next repeater unit selector is now in a position to respond. Thus by a number of interruptions of the polarity followed by a double reverse of the polarity selects a particular unit selector. The relays 17 and 18 may be replaced by electronic equivalents.