Distributed optical fiber acoustic sensing system (DAS) can achieve real-time monitoring of vibration events along the optical fibers by demodulation of back Rayleigh scattered light information in optical fibers. DAS system has a long detection distance, low cost, high sensitivity and other characteristics, and has been playing an important role in various engineering applications. However, in practical engineering detection of DAS system, there are other vibration sound sources in the environment besides target vibration events. However, the number and type of environmental sound sources are usually unknown. This kind of uncertain multi-source interference will have a serious impact on the monitoring of target events.
Distributed optical fiber acoustic sensing system (DAS) can achieve real-time monitoring of vibration events along the optical fibers by demodulation of back Rayleigh scattered light information in optical fibers. DAS system has a long detection distance, low cost, high sensitivity and other characteristics, and has been playing an important role in various engineering applications. However, in practical engineering detection of DAS system, there are other vibration sound sources in the environment besides target vibration events. However, the number and type of environmental sound sources are usually unknown. This kind of uncertain multi-source interference will have a serious impact on the monitoring of target events.
Distributed Acoustic Sensing (DAS) based on backscattered Rayleigh scattering in optical fibers is a rapidly developing technology in recent years. It utilizes the backscattered light from Rayleigh scattering in optical fibers for sensing purposes. By demodulating the phase information of the backscattered light, it enables highly sensitive distributed detection of external vibrations. DAS can provide real-time monitoring of small vibration signals near the optical fiber, showcasing extensive applications in the field of marine fishery monitoring. However, there is currently a lack of theoretical knowledge regarding the acoustic response characteristics of DAS to fish sounds. In order to provide theoretical guidance for future cable laying and fish sound monitoring work, this study considers the marine environment as an isotropic homogeneous medium. It investigates the acoustic response characteristics of the DAS system under different fish sounds and cable deployment methods in the marine environment. The feasibility of using a distributed optical fiber acoustic sensing system to monitor fish vocalizations is theoretically demonstrated, further promoting diversification in passive monitoring approaches for marine fisheries.
KEYWORDS: Sensing systems, Optical fibers, Control systems, Signal detection, Field programmable gate arrays, Demodulation, Digital electronics, Light scattering, Data acquisition, Spatial resolution
With the increasing application of distributed fiber acoustic sensing (DAS) technology in oil and gas resource detection, more attention has been attracted to the practicability and applicability of the DAS system. As an essential part of improving the system performance, the pulse signal generator unit has some problems such as high cost, single pulse parameters, and small range. In order to solve the issues mentioned above, an adjustable pulse unit applied in the DAS system is designed in this paper. The adjustable pulse unit takes the field programmable gate array (FPGA) chip as the hardware platform and keeps the variable frequency division technology and the pulse edge adjustment circuit as the critical module to generate the pulse signal with continuously adjustable pulse repetition rate, pulse width, and pulse edge. The host computer real-time controls the adjustable pulse unit to adjust the optical pulse parameters. The experimental results show that the adjustable pulse unit can achieve the functions of pulse width 5 ns ~ (1/pulse repetition frequency - 5ns), pulse repetition frequency 1 Hz ~ 50 MHz, and pulse edge 2.53 ns ~ 8.8 ns, which meet the requirements of the design. At last, the adjustable pulse unit applies to the DAS system. The results show that the adjustable pulse unit is well performed in the system, enabling the system to achieve high-quality vibration signal detection in positioning and restoring the external vibration signal. It proves the feasibility of the design scheme and achieves the expected effect. The design improves the flexibility and applicability of the DAS system in engineering applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.