USA As Represented by Secretary of the Navy

Antonio L Deus

Gerald L Assard

Robert J Reid

Barry A Blakely

Russel A Racette, Iii

Bradford A Wheeler

A portable tracking array to be used in a system for determining the track nd/or the range of a target vehicle. The array includes a fiber optic hydrophone for acquiring acoustic signals from the target vehicle. The fiber optic hydrophone is encapsulated within a plastic material such as polyurethane. The array further includes a fiber optic cable for transmitting signals to and for receiving signals from the fiber optic hydrophone, which fiber optic cable has an end encapsulated within a termination coupling, and a length of perforated material extending between the terminal coupling and the plastic material encapsulating the fiber optic hydrophone to allow water entry and to substantially eliminate air cavities which interfere with acoustic performance.

Portable optical range tracking array

A digital receiver system is used to recover a signal of interest, such as measurand signal, from a phase modulated signal detected from a system utilizing quadrature carriers, such as a fiber optic interferometer sensor system. The digital receiver system includes a quadrature sampling demodulator that samples the phase modulated signal by using quadrature sampling periods to recover the odd and even components of the signal of interest. The digital receiver system can be used with an interferometer sensor system having an array of sensors that multiplex the measurand signals, e.g., using time or wavelength division multiplexing. Sampling with quadrature time samples provides a spacing in time between the samples that allows additional sensors to be multiplexed.

System and method for recovering a signal of interest from a phase

A method and apparatus for sensing and measuring vibrational energy in a structure subject to vibrations is described. The method comprises the steps of applying a thin transparent film material having a thickness to a structure subject to vibrations and measuring the vibrational energy within the structure by measuring changes in the thickness of the thin transparent film material resulting from vibrations within the structure being transmitted to the thin transparent film material. The apparatus for sensing and measuring the vibrational energy comprises a light source for generating a coherent light beam, the thin transparent film material, and a detector for receiving reflected light rays from the top and bottom surfaces of the film material.

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Westerly, RI, United States of America

Antonio L Deus