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A temperature measurement of a high voltage bushing (HV-Bushing) is presented. An optical fiber with several inscribed Fiber Bragg Gratings (FBGs) was used to measure the temperature at given positions and a Rayleigh-based measurement technique was used to measure the temperature (profile) between the FBGs. The used optical frequencies for the FBG and Rayleigh measurement had to be separated to achieve...
In this work, a fiber identification method based on incoherent optical frequency domain reflectometry (lOFDR) measurements is introduced. The proposed method uses the characteristic interference pattern of IOFDR Rayleigh backscatter measurements with a broadband light source to unambiguously recognize different initially scanned fiber segments. The recognition is achieved by crosscorrelating the...
We present a technique to overcome the random transfer function of fiber-optic direct detection coherent optical time-domain reflectometry (C-OTDR). For this purpose, a standard optical fiber was treated by UV light in order to introduce local strongly scattering segments of definite size and distance to each other. Dynamic strain measurements were performed to demonstrate the sensory benefit in comparison...
In Rayleigh-scattering-based Distributed Acoustic Sensing (DAS) an optical fiber is transformed into an array of thousands of ‘virtual microphones’. This approach has gained tremendous popularity in recent years and is one of the most successful examples of a fiber-optic sensing method which made its way from the academia to the market. Despite the great amount of work done in this field, sensitivity,...
Coherent fading noise (also known as speckle noise) affects the SNR and sensitivity of Distributed Acoustic Sensing (DAS) systems and makes them random processes of position and time. As in speckle noise, the statistical distribution of DAS SNR is particularly wide and its standard deviation (STD) roughly equals its mean (σSNR/〈SNR〉 œ 0.89). Trading resolution for SNR may improve the mean SNR but...
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