Optics: measuring and testing – For optical fiber or waveguide inspection
Reexamination Certificate
2007-09-18
2007-09-18
Nguyen, Tu T. (Department: 2886)
Optics: measuring and testing
For optical fiber or waveguide inspection
Reexamination Certificate
active
11056629
ABSTRACT:
A CW lightwave modulated by a continuously reiterated psuedorandom 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 type pseudonoise code sequence demodulation and phase demodulator units, operated in different time delay relationships to the timing base of the reiterated modulation sequences. These units provide outputs representative of phase variations in respective unique spectral components in the r.f. beat signal caused by acoustic, or other forms of, signals incident to virtual sensors at fiber positions corresponding to the various time delay relationships.
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Kasischke James M.
Nasser Jean-Paul A.
Nguyen Tu T.
Stanley Michael P.
The United States of America represented by the Secretary of the
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