Back to results
US 11,378,443 B2Granted
Performance of Rayleigh-based phase-OTDR with correlation-based diversity combining and bias removal
AssigneeNEC Corporation
InventorsEzra Ip, Yue-Kai Huang
Life of this patent
Estimating the term…
Abstract
Aspects of the present disclosure describe systems, methods and apparatus for improving the performance of Rayleigh-based phase-OTDR with correlation-based diversity combining and bias removal.
Claims4
A distributed acoustic sensing (DAS) system using phase optical time-domain reflectometry based on Rayleigh scattering comprising:
- an optical interrogator unit that generates optical pulses at one or more optical frequencies and introduces them into an optical fiber under test;
- a receiver unit that detects Rayleigh backscatter from the optical fiber under test, and
- a data processor unit that determines acoustic vibrations experienced by the optical fiber under test by computing a plurality of delay interferometric products based on different combinations of polarizations and/or frequencies of the detected Rayleigh backscatter, adding the interferometric products in phase by aligning their vectors using correlation, followed by bias removal wherein phase rotations φl,k are determined by first choosing an appropriate window size of M samples and then determining a bk [l, m] term according to the following relationship:
- k
- 0
- =
- max
- k
-
- (
- ∑
- m
- =
- 1
- M
-
-
- b
- k
-
- [
- l
- ,
- m
- ]
-
- 2
- )
- ;
- ;
- and
- subsequently determining the phase rotations by correlating remaining terms according to bk[l, m] according to the following:
- φ
- l
- ,
- k
- =
- angle
-
-
- (
- ∑
- m
- =
- 1
- M
-
- b
- k
-
- [
- l
- ,
- m
- ]
-
- b
- k
- 0
- *
-
- [
- l
- ,
- m
- ]
- )
- where bk[l, m] are delay interferometric products, l is a position index and m is a time index.
65 more elements
Dependencies are inferred from the claim text.