Echo Canceller Circuit Oversampling Signal-to-Noise Ratio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In full-duplex communication systems, unmatched transmission line impedances and improper hybrid architecture designs lead to signal echoes, degrading the signal-to-noise ratio (SNR) due to the inability of existing echo cancelling systems to effectively cancel echoes at higher sampling rates.
Innovation Solution
An echo cancelling system and method that includes a data transmitter circuit and an echo canceller circuit, which generates an echo cancelling signal at a higher sampling rate by performing oversampling and filtering processes, combining it with a random sequence signal to effectively cancel echoes and improve SNR.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If echo cancelling is performed at the original sampling rate, then the system complexity is lower, but the signal-to-noise ratio is degraded due to insufficient echo cancellation
Solution Approach 1:
The patent changes the sampling rate parameter from the original rate to a higher oversampling rate (e.g., 2x or 4x the original rate). This parameter change enables the echo canceller to generate echo cancelling signals at the higher sampling rate, improving the signal-to-noise ratio by more effectively canceling echoes and noise components that would be missed at the lower sampling rate.
Solution Approach 2:
The patent segments the echo cancellation process into multiple stages: (1) oversampling the transmitted signal to generate a higher sampling rate signal, (2) generating the echo cancelling signal at the higher sampling rate, and (3) downsampling the echo cancelling signal back to the original sampling rate before combining with the received signal. This segmentation allows the system to benefit from high-rate processing while maintaining compatibility with the original system architecture.
2Reliability
If the sampling rate is increased for echo cancellation, then more noises are cancelled and SNR is improved, but the processing requirements and system complexity increase
Solution Approach 1:
The patent implements dynamic sampling rate adjustment where the echo canceller operates at a higher sampling rate for echo signal generation, but the final output is downsampled to the original system sampling rate. This dynamic approach allows the system to achieve improved SNR through high-rate processing only where necessary (in the echo cancellation path), while maintaining the original processing speed requirements for the main data transmission path.
3Reliability
If oversampling is performed to generate higher sampling rate signals for echo cancellation, then echo cancellation effectiveness is improved, but the device complexity and cost increase
Solution Approach 1:
The patent designs the echo canceller to perform multiple functions: it receives the transmitted signal, oversamples it to generate a higher sampling rate version, uses this high-rate signal to generate the echo cancelling signal, and then downsamples the result before output. This multi-functional design consolidates what could be separate complex circuits into a single integrated echo canceller block, reducing overall system complexity while achieving improved echo cancellation effectiveness.
Data Source
AI summary
An echo cancelling system includes a data transmitter circuit and an echo canceller circuit. The data transmitter circuit is configured to receive a first transmitted signal. The first transmitted signal has a first sampling rate. The echo canceller circuit is configured to generate a second transmitted signal according to the first transmitted signal. The second transmitted signal has a second sampling rate. The second sampling rate is greater than the first sampling rate. The echo canceller circuit is further configured to generate an echo cancelling signal according to the second transmitted signal. The data transmitter circuit is further configured to generate an output signal according to a received signal and the echo cancelling signal.