Detection of Moving Objects
First Claim
1. A distributed acoustic sensor apparatus comprising:
- an interrogator unit for, in use, interrogating an optical fibre with optical radiation and producing a measurement signal indicative of incident acoustic signals from each of a plurality of sensing portions of said optical fibre; and
a processor configured to analyse said measurement signals to identify a signal characteristic of a Doppler shift so as to detect a moving object.
1 Assignment
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Accused Products
Abstract
A system for moving object (402) detection is provided, the system comprising a fibre optic interrogator (106) adapted to provide distributed acoustic sensing on a optic fibre (104), for example arranged along a border. The measurement signals from each of a plurality of sensing portions (404, 406, 408, 410, 412) of said fibre are analysed to determined a characteristic of a Doppler shift. The characteristic of a Doppler shift may be a generally continuous decrease in detected frequency. By detecting the time at which the rate of change of frequency is at a maximum for each of the sensing portions the time of closest approach (ti, t2, t3, t4, t5) of the object to those sensing portions can be determined with the sensing portion the object approaches closest to showing the greatest value of maximum rate of change of frequency. The distance of closest approach and velocity can be determined.
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Citations
38 Claims
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1. A distributed acoustic sensor apparatus comprising:
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an interrogator unit for, in use, interrogating an optical fibre with optical radiation and producing a measurement signal indicative of incident acoustic signals from each of a plurality of sensing portions of said optical fibre; and a processor configured to analyse said measurement signals to identify a signal characteristic of a Doppler shift so as to detect a moving object. - View Dependent Claims (3, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 16, 17, 18, 20, 21, 22, 23)
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2. (canceled)
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4. (canceled)
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15. (canceled)
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19. (canceled)
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24-29. -29. (canceled)
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30. A method of distributed acoustic sensing comprising:
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interrogating an optical fibre with optical radiation and producing a measurement signal indicative of incident acoustic signals from each of a plurality of sensing portions of said optical fibre; and analysing said measurement signals to identify a signal characteristic of a Doppler shift so as to detect a moving object. - View Dependent Claims (31, 36, 37)
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32-35. -35. (canceled)
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38. A method of processing data acquired from a distributed acoustic sensor to detect moving objects comprising taking data comprising measurement signals indicative of incident acoustic signals from each of a plurality of sensing portions of a distributed acoustic sensor;
- and analysing said measurement signals to identify a signal characteristic of a Doppler shift so as to detect a moving object.
Specification