Application of statistical inference to optical time domain reflectometer data

US7075632B1 · kind B1 · utility

Inventors

• Michael Asher · Green Cove Springs, US
• Hossein Eslambolchi · Los Altos Hills, US
• Chuck Giddens · Conyers, US
• John Sinclair Huffman · Conyers, US
• Harold Jeffrey Stewart · Alpharetta, US

Key dates

• Filing date: Oct 31, 2005
• Grant date: Jul 11, 2006
• Expiry date: Oct 31, 2025

Classification

• Technology area (CPC G): Physics
• CPC primary: G01M11/3145
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

The present invention relates to 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 likely cause for a length measurement to be shorter than a reference length. One technique uses a chi-squared best fit of an array reflectance spike occurrences along the fiber to a historical reference array. In that way, it can be determined whether the missing portion of the tested fiber is at an end or between the ends, providing evidence that the short length measurement results from a fiber break or from the intentional removal of a reserve loop.