Application of statistical inference to optical time domain reflectometer data
AssigneeAT&T Corp.
InventorsMichael Asher, Hossein Eslambolchi, Chuck Giddens, John Sinclair Huffman, Harold Stewart
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Abstract
The present invention relates to a method for interpreting data obtained by measuring a length of optical fiber using an optical time domain reflectometer (OTDR), and comparing that measurement to a reference measurement. The technique uses statistical inference to determine a whether a reference trace is valid by comparing that trace to a more recent test trace. The reference trace may be replaced or an alarm may be transmitted under certain conditions.
Claims10
A method for updating a reference trace of reflective characteristics in an optical fiber, the reference trace being stored in a memory, the method comprising the steps of:
- receiving parameters from a test OTDR trace Ttest of the optical fiber;
- retrieving from the memory parameters from a reference OTDR trace Tref;
- comparing a gross distance Dtest of the test OTDR trace Ttest with a gross distance Dref of the reference OTDR trace Tref using statistical bounds;
- and
- if relative magnitudes of Dtest and Dref cannot be resolved within statistical bounds, then
- (a) correlating reference fiber characteristics represented by an array parameter P[ ]ref with test fiber characteristics represented by an array parameter P[ ]test;
- and
- (b) replacing the reference OTDR trace Tref in the memory with the test OTDR trace Ttest if there is a statistically significant variance between the array parameters P[ ]ref and P[ ]test.
Dependencies are inferred from the claim text.