Audio Signal Attenuation for Battery Brownout Prevention

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Solution Overview

Problem

Far-field speakers in mobile stations can cause battery voltage to brown out due to increased current demands, leading to potential shutdowns or resets, especially when using high audio output power.

Innovation Solution

Monitoring the battery voltage and digital audio signal levels, applying attenuation to the audio signal when the voltage falls below a threshold to reduce the risk of brownouts and resets, by determining the necessary attenuation based on both battery voltage and audio signal levels.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If the far-field speaker outputs audio signal at high volume, then the audio output power is improved, but the battery voltage brown out risk increases

Engineering Contradiction:

Improveaudio output powerVSAvoidbattery voltage stability

Core Design Contradiction:

PowerVSReliability

Solution Approach 1:

The system performs preliminary monitoring of battery voltage and audio signal levels before the brown out condition occurs. When the battery voltage falls below a threshold and audio signal exceeds a threshold, attenuation is applied in advance to prevent the brown out condition, thereby maintaining system reliability while allowing high power operation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system continuously monitors battery voltage and audio signal levels, and dynamically adjusts the audio signal attenuation based on these measurements. This feedback mechanism allows the system to maintain audio output power within safe limits that prevent battery voltage brown out while maximizing usable audio power

Inventive Principle:

Principle #23Feedback

2Reliability

If the audio signal attenuation is applied, then the battery voltage stability is improved, but the audio output power decreases

Engineering Contradiction:

Improvebattery voltage stabilityVSAvoidaudio output power

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The attenuation level is not fixed but dynamically adjusted based on real-time battery voltage and audio signal level measurements. The system calculates the maximum allowable audio signal level that prevents brown out conditions, allowing the audio output power to be maximized within the safe operating range defined by battery capabilities

Inventive Principle:

Principle #15Dynamics

3Reliability

If the maximum allowable SPL is limited, then the battery voltage brown out risk is reduced, but the audio output quality deteriorates

Engineering Contradiction:

Improvebattery voltage stabilityVSAvoidaudio output quality

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

Instead of imposing a fixed maximum SPL limit, the system dynamically determines the maximum allowable audio signal level based on real-time battery voltage measurements and audio signal characteristics. This allows the audio output quality to be optimized for each operating condition while preventing brown out conditions

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP2664196B1Battery power monitoring and audio signal attenuation

Publication Date: 2019.05.01 QUALCOMM INC

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AI summary

To reduce the risk of brown outs and resets in a mobile station using a far-field speaker, a voltage level of a battery and a level of an input audio signal are monitored. When the level of the audio signal increases past a threshold level, and the voltage level of the battery falls below a threshold voltage, an attenuation is determined and applied to the audio signal. The applied attenuation reduces the volume of the audio signal, which reduces the risk of a brown out or a reset due to insufficient voltage in the mobile station.