Optical Network Device Frequency-Independent Signal Splitting
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Solution Overview
Problem
Current R-ONU devices require frequent and costly replacements when the frequency split between upstream and downstream signals changes, as they rely on fixed-frequency diplex filters, making it impractical to adapt to changes in network requirements for faster and widerband upstream signals.
Innovation Solution
An optical network device with separate upstream and downstream signal paths utilizing a frequency-independent signal splitting element, such as a directional coupler or hybrid coupler, to isolate signals effectively, allowing the device to remain operational without needing replacement when frequency splits change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed-frequency diplex filter is used to isolate upstream and downstream signals, then signal isolation is achieved, but the device must be replaced when frequency split changes
Solution Approach 1:
The patent changes the key parameter of the signal splitting element from fixed frequency response to variable frequency response. The directional coupler's coupling factor and isolation characteristics can be adjusted to work across different frequency splits (e.g., 70/108 MHz, 54/108 MHz, 200/250 MHz), eliminating the need for device replacement when network frequency allocations change.
Solution Approach 2:
The directional coupler is designed to perform multiple functions across different frequency configurations. A single device can handle various upstream/downstream frequency allocations by adjusting its coupling characteristics, making it universally applicable to different network standards and future upgrades without requiring replacement.
2Adaptability or versatility
If signal filters are altered for each frequency split change, then the device adapts to new frequency requirements, but the process becomes time-consuming and expensive
Solution Approach 1:
The patent introduces dynamic adjustability to the signal splitting element. The directional coupler can be reconfigured to change its frequency response characteristics, allowing the device to adapt to different frequency splits without physical replacement. This dynamic capability eliminates the time-consuming process of filter alteration and device replacement.
3Reliability
If a high isolation signal splitting element is used to prevent signal leakage, then downstream signal leakage into upstream path is reduced, but device complexity increases
Solution Approach 1:
The directional coupler acts as an intermediary element between upstream and downstream signal paths. It provides the necessary isolation (30-50 dB) to prevent downstream signals from leaking into the upstream path while maintaining a relatively simple structure. The coupler's inherent directional properties naturally provide isolation without requiring complex active control circuits.
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 the optical network device to maintain functionality and prevent signal leakage across frequency changes, eliminating the need for device replacement and reducing operational costs associated with frequent upgrades.
Implementation Method 1
the signal splitting element is capable of splitting signals independent of signal frequency and is configured with an isolation of 30 to 50 dB, preferably an out-to-coupler isolation
Implementation Method 2
a wavelength division multiplexing unit connected by way of separate upstream and downstream paths to a signal splitting element
Implementation Method 3
The R-ONU converts the optical RF over glass signals to electrical RF over coax signals for downstream signals
Implementation Method 4
electrical RF over coax signals to optical RF over glass signals for upstream signals
Data Source
AI summary
There is provided an optical network device (30) comprising separate downstream and upstream signal paths (33, 34) disposed between a wavelength division multiplexing unit (16) and a signal splitting element (32, 44, 50), an optical to electrical signal converter (18) disposed in the downstream path and an electrical to optical signal converter (22) disposed in the upstream path, wherein the signal splitting element (32, 44, 50) is capable of splitting signals independent of signal frequency and is configured with an isolation of 30 to 50 dB thereby to substantially prevent leakage of downstream signals into upstream path (34). The signal splitting element is capable of splitting signals independent of signal frequency and may be a directional coupler, two-way signal splitter or hybrid coupler comprising at least two different types of coupler element.