Forward Phase Sensing with SIC for Multi-Span Fiber Vibration Isolation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Distributed Acoustic Sensing (DAS) systems struggle to monitor multiple spans of fiber in telecommunications networks due to isolators in inline amplifiers and low signal-to-noise ratio, while forward phase sensing lacks location information for vibration signals, making it difficult to isolate sources in multi-span fiber networks.
Innovation Solution
Combining DAS and forward phase sensing systems at add/drop nodes, with DAS providing precise location information, and applying successive interference cancellation (SIC) to isolate vibration signals from intermediate spans by using time delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If DAS systems are used to monitor fiber spans, then precise location information of vibration sources is obtained, but the monitoring range is limited to the first span due to isolators in inline amplifiers
Solution Approach 1:
The patent combines DAS and forward phase sensing systems into a hybrid architecture. DAS provides precise location information for vibrations in the first span, while forward phase sensing monitors the entire multi-span link. The two systems are merged through a signal processing unit that correlates DAS location data with forward phase sensing signals to achieve both precise localization and extended monitoring range across multiple spans.
2Length of moving object
If forward phase sensing is used to monitor entire link, then monitoring range is extended to multi-span fiber networks, but location information for vibration signals is lost
Solution Approach 1:
The patent introduces DAS as an intermediary system that provides location information for the forward phase sensing system. The DAS system acts as a mediator that identifies vibration locations in the first span, which then serve as reference points for the forward phase sensing system to attribute phase changes to specific locations along the multi-span link, thereby recovering location information.
3Adaptability or versatility
If multiple vibration sources exist along the fiber, then comprehensive monitoring is achieved, but it becomes extremely challenging to isolate and separate different vibration signals from different locations
Solution Approach 1:
The patent segments the multi-span fiber link into individual spans and uses DAS to provide precise location information for each segment. By dividing the monitoring task into span-specific segments and using DAS location data to attribute forward phase sensing signals to specific spans, the system can isolate and separate vibration signals from different locations even when multiple vibration sources exist simultaneously along the fiber.
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
Enhances localization characteristics and isolates vibration sources with higher fidelity by removing interfering signals, improving overall system performance in multi-span fiber networks.
Implementation Method 1
due to the reliance of DAS on Rayleigh back-scattering mechanisms
Implementation Method 2
Forward phase sensing can be implemented using bidirectional laser interferometry
Data Source
AI summary
Disclosed is a WDM network in which both DAS and forward phase sensing systems are deployed at add/drop nodes of fiber links. Whereas DAS systems can monitor immediate fiber spans connected to the add-drop nodes, forward phase sensors will monitor an entire link between the nodes. With DAS providing precise locations of vibration sources at the immediate fiber spans, we utilize that information and successively subtract these vibration signals (by applying proper time delay according to their location) from the forward phase signal monitoring of the entire link. The resulting signal after successive interference cancellation (SIC) only contains phase information at intermediate fiber spans, effectively isolating those signal sources from the those retrieved by DAS.