Variable Optical Attenuator for Dynamic Signal Intensity Control
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Solution Overview
Problem
In passive optical communication networks, subscriber terminals at greater distances from the optical splitter receive optical signals with intensities outside their dynamic range, leading to failed presence checks due to either overly strong or weak signal intensities.
Innovation Solution
A subscriber terminal equipped with a variable optical attenuator, optical-electric converter, clock extractor, and controller adjusts the optical signal intensity by determining stable clock extraction and setting appropriate attenuation values to keep the signal within the dynamic range during presence checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the optical signal intensity is increased to ensure reception at distant subscriber terminals, then the signal can be received at greater distances, but the signal intensity becomes too strong for nearby subscriber terminals causing them to fail presence checks
Solution Approach 1:
The patent applies dynamics by making the optical attenuator adjustable and controllable in real-time. The controller dynamically adjusts the attenuation amount based on the subscriber terminal's distance from the optical splitter, transforming a static attenuation setting into a dynamic adaptive system that resolves the contradiction between serving distant and nearby terminals
Solution Approach 2:
The patent changes the parameter of attenuation amount from a fixed value to a variable parameter controlled by the controller. By adjusting the attenuation parameter based on distance information, the system adapts the optical signal intensity to match the specific requirements of each subscriber terminal, resolving the intensity contradiction
2Reliability
If the optical signal intensity is decreased to protect nearby subscriber terminals from overload, then nearby terminals can receive signals properly, but distant subscriber terminals receive signals that are too weak for proper reception
Solution Approach 1:
The patent applies local quality by providing different attenuation levels to different subscriber terminals based on their specific locations. Each terminal receives a customized attenuation setting tailored to its distance from the optical splitter, allowing nearby terminals to receive weak signals without overload while distant terminals receive strong signals with appropriate attenuation
3Device complexity
If a fixed attenuation value is used in the optical attenuator, then the device complexity is reduced, but the system cannot adapt to different distances causing presence check failures
Solution Approach 1:
The patent applies universality by designing the controller to perform multiple functions: it determines the subscriber terminal's distance from the optical splitter, calculates the appropriate attenuation amount, and controls the optical attenuator. This multi-functional controller avoids the need for separate complex mechanisms while achieving adaptability across different distances
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
Ensures reliable reception of presence check request signals by maintaining the optical signal intensity within the dynamic range, preventing failures in presence checks and improving communication reliability.
Implementation Method 1
a variable optical attenuator which attenuates an optical signal received from the central-office apparatus
Implementation Method 2
an optical-electric converter which converts the optical signal received via the variable optical attenuator to a corresponding electric signal
Data Source
AI summary
A subscriber terminal connected to a central-office unit in an optical communication network includes a variable optical attenuator for attenuating an optical signal received from the central-office unit; an optical-electric converter for converting the optical signal received via the attenuator to a corresponding electric signal; a clock extractor for extracting a clock from the electric signal and producing a clock extraction information signal representing whether or not the clock is extracted stably; and a terminal controller. The controller includes a clock extraction decider for determining whether or not the extractor stably extracts the clock on the basis of the information signal, a receiving level adjuster for setting an attenuation value to a value between a minimum and a maximum value, and an attenuation controller for setting the attenuation amount for the attenuator to the set attenuation value.