Analog Echo Cancellation With DAC Noise Suppression
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Solution Overview
Problem
In Hybrid Fiber-Coaxial (HFC) networks, analog echo cancellation is challenging due to downstream signal echoes that interfere with upstream signals, leading to noise contamination and reduced Signal-to-Noise Ratio (SNR) in full duplex Data Over Cable Service Interface Specification (DOCSIS) operations.
Innovation Solution
Analog echo cancellation with Digital-to-Analog Converter (DAC) noise suppression is implemented by sending a test signal through the echo cancellation pathway during silence periods, creating a channel response model and a non-linear model, generating a non-linear component, convolving it with the channel response, and subtracting it from the upstream signal to cancel out echoes and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If analog echo cancellation is implemented using DAC components, then downstream signal echoes can be cancelled, but DAC noise is introduced and degrades signal quality
Solution Approach 1:
The echo cancellation signal path is segmented into multiple DAC components (first DAC for downstream echo cancellation, second DAC for upstream echo cancellation). This segmentation allows independent noise management for each direction, preventing the accumulation of DAC noise in a single path while maintaining effective echo cancellation in both downstream and upstream directions.
2Reliability
If echo cancellation pathway gain is increased to cancel stronger echoes, then echo suppression improves, but receiver dynamic range is reduced and noise performance deteriorates
Solution Approach 1:
The system dynamically adjusts the gain parameter of the echo cancellation pathway based on signal conditions. By changing the gain parameter adaptively rather than using a fixed high gain, the system achieves effective echo suppression while maintaining the receiver dynamic range within optimal limits, preventing noise performance deterioration.
Data Source
AI summary
Analog echo cancellation with Digital-to-Analog Converter (DAC) noise suppression may be provided. First, a test signal may be sent through an echo cancellation pathway during a downstream silence period and an upstream silence period. The echo cancellation pathway may comprise an electronic element. Next, a loopback response signal may be received in response to sending the test signal through the echo cancellation pathway. Then a channel response model may be created that characterizes a channel response of the loopback response signal and a non-linear model may be created that characterizes a non-linearity of the electronic element. Next, for a downstream signal, a non-linear component may be generated based on the created non-linear model. The generated non-linear component may be convolved with the created channel response model. The convolved non-linear component may then be subtracted from an upstream signal.