Full-Duplex Cable Modem Echo Cancellation Calibration
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Solution Overview
Problem
Full-duplex cable modems face interference issues due to echoes of upstream transmissions, which degrade signal quality and require costly switched diplexer filters, and existing echo cancellation methods are sensitive to component variations and environmental changes, making self-installation challenging.
Innovation Solution
A full-duplex cable modem system with built-in echo cancellation circuitry and calibration processes, including factory calibration and run-time diagnostics, to autonomously select frequencies, measure echoes, and adjust echo canceller coefficients, eliminating the need for switched diplexer filters and enabling self-installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If echo cancellation circuitry is implemented in full-duplex cable modems, then adjacent channel and leakage interference are reduced by approximately 50 dB and 55 dB, but the system becomes sensitive to component variations and environmental changes, making self-installation challenging
Solution Approach 1:
The patent applies preliminary action through factory calibration processes that pre-determine optimal echo canceller coefficients before the modem is deployed. The calibration is performed in advance using controlled test conditions, and the results are stored for use during actual operation, eliminating the need for complex real-time adjustments during self-installation.
Solution Approach 2:
The patent implements self-service through automated calibration processes that allow the modem to autonomously measure echoes and adjust echo canceller coefficients without requiring manual intervention. The system performs self-diagnosis and self-adjustment during run-time, enabling customers to install the modem themselves without technician assistance.
2Extent of automation
If factory calibration and run-time diagnostics are implemented, then autonomous frequency selection and echo measurement capabilities are achieved, but device complexity increases
Solution Approach 1:
The patent merges factory calibration and run-time diagnostics into a unified calibration system with common functional blocks. The echo canceller, calibration signal generator, and measurement circuits are integrated across both calibration phases, reducing overall system complexity despite the extended automation capabilities.
Solution Approach 2:
The patent applies universality by designing calibration circuits and components that serve multiple functions: the same echo canceller circuitry is used during both factory calibration and run-time operation, and the calibration infrastructure supports both automated and manual calibration modes, reducing the need for dedicated components.
Data Source
AI summary
A cable modem comprises transmitter circuitry, receiver circuitry, and memory. Upon power up of the cable modem in the field, the transmitter circuitry transmits one or more first signals into a network. The receiver circuitry measure echoes of the transmitted one or more first signals. The receiver circuitry generates an installation figure of merit based on the measured echoes and factory-calibration echo measurements stored in the memory. The communication device begins DOCSIS® network registration if the installation quality measurement meets a determined requirement and generates a notification to troubleshoot the installation of the communication device if the installation quality measurement does not meet a determined requirement.