Drop Fiber Intrusion Detection via Signal Multiplexing
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Solution Overview
Problem
Existing optical fiber intrusion detection systems are limited in their ability to discern which specific branch or drop fiber is being disturbed within a network, particularly in Passive Optical Network (PON) architectures, where multiple premises are served by a single optical fiber.
Innovation Solution
A method that utilizes a multiplexing system to separate and analyze monitor signals across multiple drop fibers, modifying the monitor signal at the source or terminals to differentiate between fibers based on wavelength, polarization, or frequency, allowing for the detection of intrusion events and identification of affected fibers through unique signal characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single optical fiber is used to serve multiple premises in a PON architecture, then the amount of fiber and equipment required is reduced, but the ability to discern which specific branch or drop fiber is being disturbed is lost
Solution Approach 1:
The patent segments the monitoring function by distributing monitoring devices to both ends of the fiber. Each end independently monitors the same fiber, dividing the monitoring task into separate functional segments that work together to achieve complete coverage and identification capability
Solution Approach 2:
The patent introduces an intermediary identification mechanism where each monitoring device is assigned a unique identifier. This intermediary element allows the system to distinguish which specific device detected the disturbance, thereby identifying the affected drop fiber without requiring separate physical monitoring paths
2Measurement precision
If monitoring devices are distributed to both ends of the fiber, then the ability to identify affected fibers is improved, but the system complexity increases
Solution Approach 1:
The monitoring devices at both ends perform the same universal monitoring function using identical or similar technology. This multi-functionality approach allows either end to independently detect disturbances, eliminating the need for complex specialized equipment at each location while maintaining high identification accuracy
3Reliability
If traditional alarmed carrier systems are used with two fibers, then reliable monitoring is achieved, but the cost and complexity of the system increases
Solution Approach 1:
The patent merges the monitoring functions that traditionally required two separate fibers into a single fiber system. By combining the monitoring capabilities at both ends of one fiber and using identifier-based discrimination, the system achieves reliable monitoring equivalent to traditional two-fiber systems while reducing infrastructure complexity
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
Enables accurate detection and differentiation of intrusion events on specific drop fibers within a PON network, enhancing security and reducing the complexity and cost of monitoring systems by using existing infrastructure and low-cost electronic analysis.
Implementation Method 1
transmitting a monitoring signal through a fiber
Implementation Method 2
uses Fresnel reflections and Rayleigh backscattering in time sliced data to locate the intrusion event at its position along a fiber
Implementation Method 3
uses Fresnel reflections and Rayleigh backscattering in time sliced data to locate the intrusion event at its position along a fiber
Implementation Method 4
modifying the monitor signal at said monitor signal source and/or at said multiplexing and/or at said returning so that the monitor signal of one drop fiber has a difference from the monitor signal of another drop fiber
Implementation Method 5
modifying the monitor signal at said monitor signal source and/or at said multiplexing and/or at said returning so that the monitor signal of one drop fiber has a difference from the monitor signal of another drop fiber
Data Source
AI summary
A method is provided for detecting movement indicative of intrusion events on optical drop fibers of a network where the individual drop fiber can be identified to locate the event. The method uses a monitor system at the network end and multiplexing the monitor signal along the individual fibers to the respective terminals. At each of the terminals, the monitor signal is returned unchanged or in modified form along the same or different fibers to the network end. At the network end the received monitor signals is analyzed for changes in said monitor signals indicative of movement. Which one or more of the drop fibers has triggered the alarm is determined by modifying the monitor signal in wavelength or polarization, or by applying a modulation at the source and/or at multiplexing and/or at returning so that the monitor signal of one drop fiber has a difference from the monitor signal of another drop fiber.