Evaluating the position of a disturbance
US7974182B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 31, 2005 |
| Grant date | Jul 5, 2011 |
| Priority date | — |
| Expiry date | Jun 1, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01M11/3172
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
The position of a disturbance on an optical link is evaluated, in particular where the disturbance is a time-varying disturbance. An optical time domain reflectometry technique is used in which a series of low coherence test pulses is launched by means of an optical pulse source into an the optical link, and the backscattered return signal is monitored. The test pulses pass through an unbalanced Mach Zhender interferometer with the result that for each test pulse, a pair of time-displaced pulse copies is launched onto the link. The backscattered return signal is passed through the same interferometer, which causes the pulse copies of each pair to become realigned and to interfere with one another. A time-varying disturbance is likely to affect each pulse copy of a pair differently. As a result, an abnormality such as a step is likely to occur in the backscattered signal. From the time position of an abnormality, the distance of the disturbance responsible is evaluated.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.