Echo Cancellation Circuit with Analog-Digital Segmentation
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Solution Overview
Problem
Conventional communication apparatuses struggle to accurately control echo signals and transmitting power in full duplex Ethernet networks, leading to noise and distortion issues due to interference from echo and near-end cross talk.
Innovation Solution
A communication apparatus comprising a transmitter, receiver, digital echo cancellation circuit, and parameter control circuit that converts digital signals to analog, determines echo estimation components, and adjusts echo cancellation resistors and capacitors to minimize echo and optimize transmitting power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional echo cancellation technology is used, then echo signals can be reduced, but the echo cannot be controlled to the smallest and transmitting power cannot be precisely controlled
Solution Approach 1:
The patent segments the echo cancellation into two distinct parts: an analog echo cancellation circuit that processes the analog output signal before transmission, and a digital echo cancellation circuit that processes the digital input signal after reception. This segmentation allows each circuit to operate optimally in its respective domain, achieving precise echo control without compromising signal quality.
Solution Approach 2:
The patent introduces an intermediary control signal generated by the analog echo cancellation circuit that provides accurate echo information to the digital echo cancellation circuit. This intermediary signal acts as a mediator that enables precise coordination between the two cancellation circuits, allowing the system to control echo to the smallest level while maintaining reliable signal quality.
2Reliability
If error information from data slicer is used, then echo cancellation can be performed, but the signal contains too much noise and error causing distortions
Solution Approach 1:
The patent performs preliminary echo cancellation in the analog domain before the signal is converted to digital and processed by the data slicer. By canceling echo at the analog stage using the analog echo cancellation circuit, the system prevents noise and errors from being introduced by the data slicer, thereby maintaining high signal purity while achieving effective echo cancellation.
Solution Approach 2:
The patent replaces the conventional approach of using data slicer error information (which is noisy and error-prone) with an analog echo cancellation mechanism that operates on the clean analog output signal. This substitution eliminates the source of noise and errors, allowing echo cancellation to be performed with high precision without compromising signal quality.
3Device complexity
If single digital echo cancellation is used, then circuit complexity is reduced, but echo cannot be controlled to the smallest level
Solution Approach 1:
The patent divides the echo cancellation function into two specialized circuits: an analog echo cancellation circuit for processing the transmit signal path and a digital echo cancellation circuit for processing the receive signal path. This segmentation allows each circuit to be optimized for its specific function, achieving the smallest possible echo control accuracy while keeping each individual circuit relatively simple.
Solution Approach 2:
The analog echo cancellation circuit generates its own control signal from the analog output signal, which is then used by the digital echo cancellation circuit. This self-service mechanism allows the system to achieve precise echo control through coordinated operation of the two circuits without requiring complex external control mechanisms.
Data Source
AI summary
A communication apparatus with echo cancellation includes a transmitter, a receiver, a digital echo cancellation circuit, a parameter control circuit, and an analog echo cancellation circuit. The digital echo cancellation circuit determines an echo estimation component according to a digital output signal, and performs a digital echo cancellation on a digital input signal according to the echo estimation component. The parameter control circuit generates a control signal according to the echo estimation component. The analog echo cancellation circuit includes a first echo cancellation resistor and a second echo cancellation resistor, wherein the resistances of the first echo cancellation resistor and the second echo cancellation resistor are adjusted according to the control signal.