Natural fiber span reflectometer providing a virtual differential signal sensing array capability
US7274441B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Feb 7, 2005 |
| Grant date | Sep 25, 2007 |
| Priority date | — |
| Expiry date | Nov 29, 2025 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01M11/3172
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A CW lightwave modulated by a continuously reiterated pseudorandom (PN) code sequence is launched into an end of a span of ordinary optical fiber cable. Portions of the launched lightwave back propagate to the launch end from a continuum of locations along the span because of innate fiber properties including Rayleigh scattering. This is picked off the launch end and heterodyned producing a r.f. beat signal. The r.f. beat signal is processed by a plurality (which can be thousands) of correlator pseudonoise code sequence demodulation and phase demodulator units operated in different delay time relationships to the timing base of the reiterated modulation sequences. Pairs of outputs of the units are connected to respective substractor circuits, each providing a signal representative of a differential signal between acoustic, or other forms of, signals incident the bounds of virtual increments of the span.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.