Audio Clipping Threshold Control for Variable Battery Voltage
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Solution Overview
Problem
Automotive audio amplifiers face distortion issues due to varying battery supply voltages, with existing solutions either maintaining constant distortion across channels or setting thresholds too low to optimize audio amplification across a wide range of voltages.
Innovation Solution
A system that adjusts the clipping threshold based on the supply voltage, using a voltage sensor to control the gain and compression of audio signals, ensuring optimal amplification and minimizing distortion by varying the threshold according to the available power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the clipping threshold is set much lower than the actual level available from the battery to account for variations in power supply, then distortion is controlled for each channel independently, but the amplification of the audio signal is not optimal for a wide range of battery supply voltages
Solution Approach 1:
The patent implements a dynamic clipping threshold that automatically adjusts based on the detected battery supply voltage. The system transitions from a static, hard-coded threshold to a dynamic threshold that adapts to varying power conditions, allowing optimal amplification across different voltage levels while maintaining distortion control.
Solution Approach 2:
The patent changes the parameter of the clipping threshold from a fixed value to a variable value that depends on the battery voltage. By detecting the actual supply voltage and scaling the threshold accordingly, the system optimizes audio signal amplification for the current power conditions while preventing distortion.
2Productivity
If the threshold is set to maximize power output at high battery voltages, then audio amplification is optimized, but distortion control is compromised when battery voltage decreases
Solution Approach 1:
The patent employs a feedback mechanism where the battery supply voltage is continuously detected and used to adjust the clipping threshold. This closed-loop control ensures that the threshold always corresponds to the actual available power, maintaining both optimal power output and distortion control across varying battery conditions.
3Ease of manufacture
If a hard-coded threshold is used in the digital signal processor, then distortion limiting is simple to implement, but it cannot provide optimal amplification for a wide range of battery supply voltages
Solution Approach 1:
The patent transforms the static, hard-coded threshold into a dynamic threshold that adapts to different battery voltages. The system maintains implementation simplicity by using the existing DSP architecture while adding voltage detection and scaling logic, achieving both ease of manufacture and voltage range adaptability.
Data Source
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AI summary
A distortion compensation system (100) minimizes distortion in an audio system by monitoring a supply voltage (134) and adjusting a clipping threshold and/or compression knee (104). An adjustable gain circuit (114,116) controls the gain of the audio signal according whether the audio signal exceeds a variable threshold (110,112). The variable threshold is adjusted within a threshold range based on the supply voltage (134). Distortion due to clipping of the audio signal is minimized while available power at any given time is maximized.