GB1000046A - Improvements in or relating to line concentrators - Google Patents

Abstract

1,000,046. Automatic exchange systems. WESTERN ELECTRIC CO. Inc. June 20, 1962, No. 23674/62. Drawings to Specification. Heading H4K. In a line concentrator system having a corresponding expander associated with the line terminations at a central office, the operations are controlled by a common circuit which on a service request allots an idle trunk and transmits its identity to the concentrator. On an originating call, a signal is sent to the control circuit to establish preference over terminating calls, and the line requesting service is identified in two stages by means of tens and units counters driven by pulses which pass also to the control circuit to drive synchronous counters thereat. A trunk selector is similarly driven in search of an idle trunk by pulses which pass also to the concentrator. As regards terminating calls, the sleeves of the lines concerned are continuously scanned, and scanning is stopped when a line bearing a service request is found. If, however, all the trunks available to a particular group of lines are busy, then the line terminations to the scanner are disabled. The operations subsequently are generally similar to those in the case of originating calls. To even out the traffic over the group of trunks means is provided in the trunk selector for applying a false busy condition periodically during the course of the scanning cycle. Specification 957,476 is referred to.