Patent ID: 11946799
Assignee: SHANGHAI INSTITUTE OF OPTICS AND FINE MECHANICS, CHINESE ACADEMY OF SCIENCES
Field: Measurement (Instruments)
Classification: CPC G | IPC G

Claim 5:
6. A signal processing method using the distributed fiber-optic acoustic sensing system as described in claim 1, comprising
step (1) collecting distributed sound field signal, wherein the distributed sound field signals collected by the distributed fiber-optic acoustic sensor are s(l,t), l represents one-dimensional axial space of the sensing optical fiber and t represents time;
step (2) dividing the subunits, wherein the total number of the sensing units in the axial direction of the distributed fiber-optic acoustic sensor is L, the sensing units are divided into M subunits in the axial direction, and the number of the sensing units in each subunit is N, and L=M×N is met, the sound field signals collected by the N sensing units in the mth subunit are:
[Sm(l0+(m−1)·N·Δz,t),Sm(l0+(m−1)·N·Δz+Δz,t),K Sm(l0+(m−1)·N·Δz+(N−1)Δz,t)] that is abbreviated as [Sm,1,Sm,2, . . . ,Sm,N]; m meets 1≤m≤M; l0 represents a starting position of the optical fiber; Δz represents the distance between the two adjacent sensing units; and the minimum value of Δz is determined by the spatial resolution of the distributed fiber-optic acoustic sensor;
step (3) conducting spatially coherent combination in the subunits and realizing signal-to-noise ratio and sensitivity enhancement, wherein the sound field signals [Sm(l0+(m−1)·N·Δz,t),Sm(l0+(m−1)·N·Δz+Δz,t),K Sm(l0+(m−1)·N·Δz+(N−1)Δz,t)] collected by the N sensing units in the mth subunit are enhanced by a spatially coherent combination algorithm to generate a signal Sm(l0+(m−1)·N·Δz+Δz,t) that is abbreviated as S′m; and after the M subunits are enhanced by array signal processing, obtained new sound field signals are [S′1,S2, . . . ,S′m, . . . , S′M]; and
step (4) realizing azimuth estimation and space orientation by the subunits serving as independent high-sensitivity signal-to-noise ratio sensors or a new array formed by the subunits, wherein each subunit can serve as the independent high-sensitivity sensor for sensing, and at the same time, Mx subunits which are adjacent or at regular intervals can also be selected from the M subunits to serve as the new sensor array; the M subunits can form one or more sensing arrays; the newly formed sensor array performs the azimuth estimation or space orientation of the signal sources by a directional array signal processing method; and the process similar to the step (3) can be repeated again to achieve signal enhancement.