Patent ID: 6269198
Filing Date: 2001-07-31
Classification: G01H,G01V

Abstract:
A frequency division multiplexed fiber optic acoustic sensor system for simultaneously detecting acoustical information at N spaced points, comprising:N light sources, wherein each light source is modulated at a different modulation frequency;N distribution fiber lines, wherein each distribution fiber line is connected to a different one of said N light sources;a return fiber line;a sensor group comprising N fiber optic acoustical sensors, wherein each acoustical sensor is connected between a different one of said N distribution fiber lines and said return fiber line; anda detector connected to said return fiber line;wherein said N modulation frequencies are selected such that:each modulation frequency has a corresponding signal component that is not overlapped in frequency space by any other modulation frequency component or by any harmonic frequency components of any order associated with any of said N modulation frequencies;a first harmonic frequency component associated with each modulation frequency is not overlapped in frequency space by any modulation frequency component or by any other harmonic frequency components of any order associated with any of said N modulation frequencies; andat least one of said N second harmonic frequencies is interleaved within said first harmonic frequencies.