Open Cable Interface Filtering for Submarine-Terrestrial Links

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Solution Overview

Problem

The interfacing of terrestrial and submarine optical networks requires specialized SLTE, which is costly and burdensome due to the need for skilled technicians and additional SKUs, complicating installation and maintenance.

Innovation Solution

An optical cable interface (OCI) with filters and variable optical attenuators is used to separate communication signals within the allowed frequency band for submarine cables from secondary signals, looping back the secondary signals to terrestrial terminals, allowing standard terrestrial equipment to detect the interface and adjust power levels without needing specialized SLTE.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If specialized SLTE equipment is used to interface submarine and terrestrial networks, then signal compatibility is achieved, but system cost and complexity increase significantly

Engineering Contradiction:

Improvesignal compatibilityVSAvoidsystem complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The interface function is segmented into two parts: a passive optical filter that separates frequency bands, and standard terrestrial equipment that handles signal processing. This eliminates the need for complex specialized SLTE while maintaining signal compatibility through frequency-based separation.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An optical filter is introduced as an intermediary component between submarine and terrestrial networks. The filter mediates the interface by passing submarine communication signals while reflecting terrestrial supervisory signals back, enabling compatibility without specialized equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If specialized SLTE equipment is used, then proper signal interface is ensured, but installation and calibration costs increase

Engineering Contradiction:

Improvesignal interface qualityVSAvoidinstallation cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The optical filter automatically performs the calibration function through its passive optical properties. Submarine signals are passed while terrestrial signals are reflected back, eliminating the need for manual calibration by skilled technicians and reducing installation costs.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If separate SKUs are assigned for SLTE and standard equipment, then equipment differentiation is achieved, but maintenance time and cost increase

Engineering Contradiction:

Improveequipment differentiationVSAvoidmaintenance time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

Standard terrestrial equipment is made universal by enabling it to interface with both terrestrial and submarine networks through the optical filter. This eliminates the need for separate SLTE SKUs and reduces maintenance complexity while maintaining proper signal handling.

Inventive Principle:

Principle #6Universality (Multi-functionality)

4Device complexity

If standard terrestrial equipment is used without specialized SLTE, then cost is reduced, but signal frequency filtering capability is lost

Engineering Contradiction:

Improveequipment simplicityVSAvoidfrequency filtering capability

Core Design Contradiction:

Device complexityVSDifficulty of detecting and measuring

Solution Approach 1:

An optical filter is introduced as a simple intermediary component that provides the necessary frequency filtering capability. The filter passively separates submarine communication signals from terrestrial supervisory signals without requiring complex active filtering in the terrestrial equipment.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 specialized SLTE, enables standard terrestrial equipment installation by ordinary technicians, and allows a single SKU for all terminals, simplifying maintenance and reducing expenses.

Implementation Method 1

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

Methodology Applied

Scientific EffectFrequency filtering: Filter (optical)

Data Source

PatentEP4067954B1Submarine cable interface for connection to terrestrial terminals

Publication Date: 2026.04.08 GOOGLE LLC

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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.