Sample Rate Converter for Echo Cancellation

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Solution Overview

Problem

Echo cancellation in hands-free voice-communication systems is incomplete when sample frequencies of signals from different units are not identical, leading to reduced echo cancellation efficiency and quality of acoustic voice signals.

Innovation Solution

An apparatus comprising a determiner, converter, adapter, and modifier that estimates the sample-frequency ratio and adjusts samples accordingly to align echo components, reducing echo magnitude by generating a modified signal that accounts for frequency differences between sampling frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If sample frequencies of signals from different units are not identical, then device complexity is reduced, but echo cancellation efficiency deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidecho cancellation efficiency

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent changes the parameter of sample frequency from being required to be identical to being allowed to differ, and introduces a sample frequency ratio parameter to characterize and compensate for the difference, thereby resolving the contradiction between device complexity and echo cancellation efficiency

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces an intermediary sample frequency ratio estimation mechanism that mediates between signals with different sample frequencies, allowing echo cancellation to work effectively without requiring identical sampling rates across different units

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If sample frequencies are not identical, then adaptability is improved, but measurement precision deteriorates

Engineering Contradiction:

ImproveadaptabilityVSAvoidmeasurement precision

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent changes the approach from requiring fixed identical sample frequencies to allowing variable different sample frequencies, using a ratio parameter to maintain precision in echo estimation despite frequency differences

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent makes the system dynamic by allowing sample frequencies to vary across units while maintaining echo cancellation precision through continuous estimation and compensation using the sample frequency ratio

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS8874175B2Converting samples of a signal at a sample rate into samples of another signal at another sample rate

Publication Date: 2014.10.28 STMICROELECTRONICS INT NV

AI summary

In an embodiment, an apparatus includes a determiner, converter, adapter, and modifier. The determiner is configured to generate a representation of a difference between a first frequency at which a first signal is sampled and a second frequency at which a second signal is sampled, and the converter is configured to generate a second sample of the first signal at a second time in response to the representation and a first sample of the first signal at a first time. The adapter is configured to generate a sample of a modifier signal in response to the second sample of the first signal, and the modifier is configured to generate a modified sample of the second signal in response to a sample of the second signal and the sample of the modifier signal. For example, such an apparatus may be able to reduce the magnitude of an echo signal in a system having an audio pickup (e.g., a microphone) near an audio output (e.g., a speaker).