High-Split Diplex Filter for Legacy STB Support
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Solution Overview
Problem
Legacy STBs restrict the upgrade of HFC plants to high-split diplex filters due to their limited frequency range, limiting achievable upstream peak data rates, and existing solutions like quadplex filters or FDX DOCSIS are costly and complex, while maintaining compatibility with legacy systems is essential.
Innovation Solution
Implementing a device with high-split diplex filters that sample and separate the DS-OOB signal, allowing it to propagate at a frequency receivable by legacy STBs, enabling gigabit speed upstream services without replacing STBs, by using circuitry to process and amplify the signal within optical nodes and RF amplifiers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-split diplex filters are implemented to increase upstream peak data rates, then upstream data rate capacity is improved, but compatibility with legacy STBs is lost
Solution Approach 1:
The downstream signal is segmented into two separate paths: one path processes the DS-OOB signal through a first diplex filter at a legacy frequency, while the other path processes conventional downstream signals through a second diplex filter at a high-split frequency. This segmentation allows the system to simultaneously support both legacy STBs and high-speed upstream services.
Solution Approach 2:
A DS-OOB signal acts as an intermediary that bridges the legacy and modern systems. The DS-OOB signal is extracted from the downstream input, processed through the first diplex filter to maintain legacy compatibility, and re-injected into the downstream output to enable legacy STB communication while the main downstream path uses high-split filtering for enhanced upstream capacity.
2Adaptability or versatility
If quadplex filters or FDX DOCSIS are used to maintain legacy STB support, then legacy compatibility is improved, but device complexity and cost increase
Solution Approach 1:
Instead of using a single complex quadplex filter, the solution segments the filtering function into two separate diplex filters. Each diplex filter handles a specific frequency range and signal type, simplifying the overall device complexity while achieving the same legacy compatibility goal.
Solution Approach 2:
The DS-OOB signal is extracted from the combined downstream signal, processed separately through the first diplex filter, and then re-injected. This extraction approach allows legacy-compatible signal processing to be separated from the main high-split downstream path, avoiding the need for complex quadplex filtering in the entire signal chain.
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 support of gigabit speed upstream services in HFC plants without replacing legacy STBs, maintaining compatibility and reducing costs associated with upgrading to high-split spectrum, while ensuring the DS-OOB signal is propagated effectively.
Implementation Method 1
separating a DS-OOB signal component from the downstream signal using a diplex filter
Implementation Method 2
propagate the DS-OOB signal at a frequency receivable by a legacy STB
Implementation Method 3
amplifier to amplify the DS-OOB signal
Data Source
AI summary
Propagating a downstream (DS) Out-of-Band (OOB) signal at a frequency receivable by a set of legacy set-top boxes (STBs) while supporting enhanced upstream peak data rates. At an input of an amplifier of a physical device, a portion of the DS-OOB signal is tapped to create a tapped DS-OOB signal, which comprises both the DS-OOB signal and all other downstream signals and channels sent from a head-end to a set of customer premises equipment (CPE) via the physical device. The tapped DS-OOB signal is introduced to a band-pass filter that passes the DS-OOB signal and attenuates all other radio frequency (RF) signals to create a filtered DS-OOB signal. The filtered DS-OOB signal is amplified and coupled to a low-pass side of a high-split diplex filter to propagate onto a transmission medium coupled to the CPE. The physical device may be a high-split RF amplifier or a high-split node.