Patent ID: 7397545

Claim:
A method for monitoring reflective characteristics in an optical fiber, by comparison to a reference trace stored in a memory, the method comprising the steps of: receiving parameters from a test OTDR trace T test of the optical fiber; retrieving from the memory parameters from a reference OTDR trace T ref ; determining whether the reference OTDR trace T ref is valid and whether an alarm condition exists by comparing the test OTDR trace T test with the reference OTDR trace T ref using a statistical comparison; and if the reference OTDR trace T ref is valid and an alarm condition exists, then: (a) conducting a one-sample z-test on an array IL[ ] test of instantaneous loss values of the test OTDR trace T test ; and (b) making a fault-type determination from the z-test of whether the alarm condition is likely due to a point fault or a cumulative fault; and (c) transmitting the alarm and the fault-type determination.