Optical Cable Interface Filtering for Submarine Terminal Links
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Solution Overview
Problem
The interfacing of terrestrial and submarine optical communication networks is costly and burdensome due to the need for specialized submarine line terminal equipment (SLTE), which requires skilled technicians for calibration and results in additional costs and complexity for maintenance.
Innovation Solution
An optical cable interface (OCI) is introduced, which filters out signals outside the allowed frequency range for submarine systems, allowing standard terrestrial equipment to connect with submarine cables, and includes features like wavelength division multiplexing filters and variable optical attenuators to adjust power levels without affecting secondary signals, enabling detection of the interface and power control without requiring specialized SLTE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If specialized submarine line terminal equipment (SLTE) is used to interface terrestrial and submarine networks, then signal compatibility and network interface reliability are improved, but system cost and device complexity increase significantly
Solution Approach 1:
The patent introduces an optical add-drop multiplexer (OADM) as an intermediary device that mediates between terrestrial and submarine optical networks. The OADM selectively drops submarine-specific wavelengths (1510nm, 1610nm) from the terrestrial network and loops them back, preventing these incompatible signals from entering the submarine cable while allowing standard terrestrial equipment to interface with submarine networks without requiring specialized SLTE
Solution Approach 2:
The patent extracts and removes the problematic secondary signals (1510nm and 1610nm wavelengths) from the optical network using wavelength-specific filters within the OADM. By taking out these incompatible frequencies before they can interfere with submarine cable operations, the system achieves reliable interfacing using standard terrestrial equipment rather than specialized SLTE
2Reliability
If specialized SLTE is deployed for submarine network interfacing, then signal compatibility is achieved, but installation and maintenance costs increase due to skilled technician requirements
Solution Approach 1:
The patent makes standard terrestrial terminal equipment universal by enabling it to interface with both terrestrial and submarine networks through the OADM. The OADM acts as a gateway that allows standard equipment to handle submarine network protocols and wavelength management, eliminating the need for separate specialized SLTE hardware and reducing installation complexity to that of standard terrestrial equipment
3Device complexity
If standard terrestrial equipment is used without filtering, then equipment cost is reduced, but harmful secondary signals interfere with submarine cable operations
Solution Approach 1:
The OADM serves as a protective intermediary that stands between standard terrestrial equipment and the submarine cable. It filters out harmful secondary signals (1510nm and 1610nm wavelengths) that would otherwise interfere with submarine cable operations, while allowing standard equipment to remain simple and cost-effective
Solution Approach 2:
The patent converts the potentially harmful secondary signals into a beneficial loopback mechanism. By filtering out the 1510nm and 1610nm wavelengths and looping them back through the OADM to the terrestrial network, these signals serve as indicators that help terrestrial network control circuitry detect the presence of submarine cable interfaces, transforming what would be interference into a useful detection mechanism
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
This solution reduces costs by eliminating the need for SLTE, allows standard terrestrial equipment to manage power levels, and simplifies maintenance by enabling a single stock keeping unit (SKU) for all terminal equipment, facilitating cost-effective and efficient interfacing between terrestrial and submarine networks.
Implementation Method 1
a first filter positioned on the first optical path and configured to: pass the first communication signals; and filter out secondary signals from the terrestrial cable, wherein the secondary signals are within a second frequency band that does not overlap with the first frequency band
Data Source
AI summary
In an optical network having a terrestrial terminal and an open cable interface (OCI) connecting a submarine cable to a terrestrial cable, the OCI may include a filter positioned on an optical path between the terrestrial cable and the submarine cable and configured to pass first communication signals of a first frequency band, and filter out secondary signals of a second frequency band that does not overlap with the first frequency band. The secondary signals may be looped back to the terrestrial terminal. The terrestrial terminal may detect the looped back secondary signals, and in response, determine the presence of the OCI and that the supervisory signals were rerouted by the OCI.