Distributed Fibre Optic Sensing Multiplexing
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Solution Overview
Problem
Conventional fibre-optic distributed acoustic sensing systems face challenges in dense acoustic environments due to low signal-to-noise ratios and the need for high sampling rates, which limits their capacity to service multiple fibre optic paths effectively.
Innovation Solution
A system and method for distributed fibre optic sensing that includes an optical signal transmitter arrangement, an optical switching arrangement, an optical signal receiver arrangement, and a processor to demodulate and process backscattered optical signals. The system configures the bandwidth of the optical signal receivers to sense backscattered signals in a reduced frequency range, reducing the required sampling rate and increasing the multiplex or switching ratio, thereby servicing more optical fibre ports.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the optical signal receiver is configured to sense backscattered optical signals in a high frequency band, then the detection capability for acoustic events is improved, but the required sampling rate increases, limiting the capacity to service multiple fibre optic paths
Solution Approach 1:
The system segments the frequency band into multiple sub-bands and processes them separately. The optical signal receiver is configured to sense backscattered optical signals in a reduced frequency range (e.g., 0-100 Hz, 0-80 Hz, 0-60 Hz, 0-40 Hz, 0-30 Hz, 0-20 Hz or 0-2 Hz), dividing the full frequency spectrum into manageable segments that can be processed at lower sampling rates while maintaining detection capability for acoustic events.
Solution Approach 2:
The system dynamically adjusts the frequency range and sampling rate based on the specific detection requirements and environmental conditions. The optical signal receiver can be configured to sense in different frequency ranges depending on the acoustic event characteristics, allowing flexible adaptation between detection precision and multiplex capacity requirements.
2Productivity
If the optical signal receiver is configured to sense backscattered optical signals in a reduced frequency range, then the required sampling rate is reduced and the multiplex ratio is increased, but the signal-to-noise ratio may be compromised in dense acoustic environments
Solution Approach 1:
The system applies different frequency ranges to different sensing zones or fibre optic paths based on their specific requirements. The optical switching arrangement sequentially distributes optical signals through multiple optical fibres via corresponding optical fibre ports, allowing each zone to be optimized for its local acoustic environment while maintaining overall system multiplex capacity.
Solution Approach 2:
The optical switching arrangement sequentially distributes optical signals in the train through the plurality of optical fibres via corresponding optical fibre ports in a time-division multiplexed manner. This periodic switching allows the system to service multiple fibre optic paths with a single optical signal transmitter and receiver, effectively increasing the multiplex ratio while maintaining adequate sampling rates for each individual path.
3Area of stationary object
If the system services more optical fibre ports through increased multiplex ratio, then the coverage area is expanded, but the acoustic event detection capability in dense environments may be reduced due to lower signal-to-noise ratio
Solution Approach 1:
The system segments the acoustic frequency spectrum and processes different frequency components separately for different fibre optic paths. By configuring the optical signal receiver to sense in reduced frequency ranges and using the optical switching arrangement to sequentially distribute signals, the system can expand coverage area while maintaining detection capability through frequency-domain segmentation.
Solution Approach 2:
The system changes the frequency parameter of the optical signal receiver configuration to optimize detection performance. The receiver can be configured to sense in different frequency ranges (0-100 Hz, 0-80 Hz, 0-60 Hz, 0-40 Hz, 0-30 Hz, 0-20 Hz or 0-2 Hz) depending on the acoustic event characteristics and environmental conditions, allowing adaptation between coverage capacity and detection precision.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enhances the system's capacity to detect acoustic events in dense environments by reducing noise interference and increasing the number of fibre optic ports that can be serviced, leading to improved signal quality and broader coverage.
Implementation Method 1
an optical signal transmitter arrangement comprising at least one optical signal transmitter for repeatedly transmitting a train of optical signals through the fibre optic network
Implementation Method 2
an optical signal receiver arrangement comprising at least one corresponding optical signal receiver for receiving backscattered optical signals from the plurality of optical fibres, the backscattered optical signals being influenced by disturbances that induce fibre optic sensing signals
Data Source
AI summary
This application is directed to distributed fiber optic sensing particularly across multiple fiber optic ports with multiple corresponding fiber optic paths. A method is implemented to repeatedly a train of optical signals through a fiber optic network including a plurality of optical fibers distributed across a geographic area using at least one optical signal transmitter, sequentially distribute optical signals in the train through the plurality of optical fiber via corresponding optical fiber ports using an optical switching arrangement, receive backscattered optical signals from the plurality of optical fibers demodulate data from the backscattered optical signals, process the data to identify at least some of the low-frequency weight-induced disturbances, and/or sense the backscattered optical signals in a reduced frequency range. The method is useful to detect low frequency weight-induced disturbances for object tracking against high noise clutter in the higher frequency signal bands.