DOCSIS-MoCA coupled line directional coupler
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Solution Overview
Problem
Existing DOCSIS and MoCA systems face challenges in providing sufficient isolation between cable signals and Internet signals, controlling insertion loss, and preventing noise funneling of interference signals, which can degrade CATV signals in the network.
Innovation Solution
A DOCSIS-MoCA coupled line directional coupler with adjustable coupling length between parallel tracks, allowing for controlled isolation and insertion loss levels across specific frequency bands, utilizing a resistor connection to optimize performance and minimize noise ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a coupled line directional coupler is used to provide isolation between cable signals and Internet signals, then isolation performance is improved, but insertion loss increases
Solution Approach 1:
The patent adjusts the coupling length parameter of the coupled line directional coupler to optimize the balance between isolation performance and insertion loss. By carefully controlling the length of the coupled lines, the design achieves sufficient isolation between DOCSIS and MoCA signals while minimizing signal attenuation in the through path.
Solution Approach 2:
The patent implements different electrical characteristics in different sections of the coupler by using specific impedance values (50 ohms for input/output ports, 75 ohms for coupled port) and varying the coupling length along the transmission lines to achieve optimal local performance for each function.
2Reliability
If filtering is applied to prevent MoCA signals from exiting the home network, then privacy is improved, but signal loss increases
Solution Approach 1:
The coupled line directional coupler acts as an intermediary device that passively directs MoCA signals to remain within the home network while allowing DOCSIS signals to pass through to the cable network. The directional coupling mechanism provides inherent signal routing without requiring active filtering that would cause signal loss.
3Object-affected harmful factors
If isolation between CATV access network signals and in-home network signals is improved, then noise ingress is reduced, but device complexity increases
Solution Approach 1:
The patent combines multiple functions (isolation, signal routing, impedance matching) into a single coupled line directional coupler structure, eliminating the need for separate filters, isolators, and matching networks that would increase device complexity while still providing comprehensive noise protection.
Data Source
AI summary
A Docsis-MoCA coupled line directional coupler includes an input port, an output port, a coupled port, and a termination port. A first track connects the input port to the output port and a second track, which may be substantially parallel to the first track, connects the termination port to the coupled port. The first track and the second track are configured to form a variable coupling length so as to control, for instance, an isolation level between the output port and the coupled port to be less than a predetermined isolation level in a MoCA frequency band.