Fault locating system capable of quickly locating a fault in a hierarchical communication network

Abstract From the Canadian patent

53, Abstract of the Disclosure:, In a fault locating system for use in combination with a communication network of a hierarchy comprising a plurality of communication units which are divisible into a plurality of layers, each of the communication units produces, on occurrence of a fault first, second, and third alarm signals Iu Id, and Ou, representative of interruption of an input signal from an upper communication unit, interruption of an input signal from a lower communication unit and interruption, of an output signal to an upper communication unit. A pattern of the first through the third alarm signals Iu to Ou is extracted from three specific communication units and is monitored to …