USA As Represented by Secretary of the Navy

Robert Michael Payton

Scott L Patton

James M Gannon

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.

Natural fiber span reflectometer providing a virtual differential signal sensing array capability

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.

Natural fiber span reflectometer providing a virtual phase signal sensing array capability

A CW lightwave modulated by a continuously reiterated autocorrelated spectrum-spreading signal is launched into an end of a span of ordinary optical fiber cable. Portions of this lightwave back propagate to the launch end from a continuum of span locations because of innate fiber properties including Rayleigh effects. This is picked off the launch end and heterodyned producing an r.f. beat signal. The beat signal is processed by a plurality (can be thousands) of multifunction despreader, autocorrelator and de-multiplexer units respectively operated in different time delayed relationships to the timing base of launch signal reiteration. This provides r.f. time-domain reflectometry outputs representative of acoustic, or other signals incident upon virtual sensors at positions along the fiber corresponding to the various delay relationships. Material attenuation of undesired noises (e.g., reflections due to presence of couplers in the fiber cable line) is effected by the spectrum spreading and de-spreading.

Natural fiber span reflectometer providing a spread spectrum virtual sensing array capability

A CW lightwave modulated by a continuously reiterated binary pseudorandom 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 to produce a r.f. beat signal. The r.f. beat signal is processed by a plurality (which can be thousands) of correlator type binary pseudonoise code sequence demodulators respectively operated in different delay time relationships to the timing base of the reiterated modulation sequences. The outputs of the demodulators provide r.f. time-domain reflectometry outputs representative of signals (e.g., acoustic pressure waves) incident to virtual sensors along the fiber at positions corresponding to the various time delay relationships.

Natural fiber span reflectometer providing a virtual signal sensing array capability

A system is disclosed that allows passage of electrical signals across a rigid boundary, such as a pressure hull of a submarine or vessel that operates in water. The passages provided by acoustic means are accomplished without any holes being made in the rigid boundary.

System for acoustically passing electrical signals through a hull

A method and optical system for fading-free reception of optical phase sils having temporally varying polarization, phase and phase frequency is provided. Two orthogonally polarized local oscillators light waves of different frequencies are utilized to produce optical interference with an unknown polarization state optical input signal. Square law detection of the resultant optical interference yields a composite radio frequency signal which is decoded into four electronic outputs. These outputs are temporally differentiated and cross multiplied to produce a single composite output corresponding to the phase rate of the optical input signal. The total power of the four electronic outputs is proportional to the input signal power. The present invention thus maintains constant signal to noise ratios and avoids the use of internal clippers and limiters.

Fading-free optical phase rate receiver

An efficient and cost effective analog telemetry system for transmitting receiving many individual data channels over long distances is provided by having each data channel signal modulate a pseudo-random number (PRN) signal which has been delayed for a distinct number of clock cycles for each data channel. The modulated PRN signals are then outputted to a single data line and summed. At the remote receiver, each data signal is recovered by cross correlating the modulated PRN signals with individual reference PRN signals. A synchronous delay generator in each data channel properly aligns each reference signal in time with its corresponding modulated PRN signal. Other modulated PRN signals, which are not aligned with the proper reference PRN signal, are rejected.

Telemetry system using broadband correlation techniques

The invention comprises a fixture and method for holding optical waveguid such as fiber optic cable, in a relatively stable fashion for processing. The fixture includes a first frame and a second frame, releasably securable to the first frame to form a unitary structure. Chambers disposed in at least one of the frames are adapted for removably receiving optical fiber cable when the first and second frames are released from one another and for securely retaining with molding material optical fiber cables when the first and second frames form the unitary structure. A process area is defined in the unitary structure such that segments of optical fiber cables secured therein are accessible in the process area for processing. An optional coating fixture is securable to said unitary structure for forming with a molding material a protective coating about the cable segments in the processing area.

Fiber optic handling and coating fixture

A method and apparatus for controlling polarization, as one of a pair of erdependent light characteristics of an optical fiber, in response to a time dependent signal without the introduction of any significant variation in phase delay. A pair of transducers compress the optical fiber at spaced locations. When phase of energization of a first transducer in response to the time dependent signal is 180.degree. out-of-phase with the energization of the second transducer, the polarization shifts in response to the time dependent signal without any significant shift is phase delay. When the phases are in-phase, phase delay shifts in response to the time dependent signal without any significant shift in polarization. Multiple sets of transducers disposed along the optical fiber enable smooth variation of the controlled polarization or phase delay when a first transducer in each set is angularly displaced about the optical fiber by 45.degree. with respect to a first transducer in an adjacent set.

Growing community of inventors

Portsmouth, RI, United States of America

Robert Michael Payton