Audio Signal Switching at Zero-Crossings for Wide Dynamic Range
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing audio amplification systems for portable devices struggle to handle audio signals with large dynamic ranges without introducing distortion or noise, especially at reduced DC power supply voltages, which limits their ability to maintain audio quality across varying sound pressure levels.
Innovation Solution
An audio signal controller that receives and processes first and second digital audio signals, estimating their features and switching between them at zero-crossings based on a predetermined criterion to prevent overload and maintain audio quality, thereby minimizing distortion and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single high-gain amplifier is used to handle low-level signals, then sensitivity is improved, but distortion and overload occur at high sound pressure levels
Solution Approach 1:
The audio signal processing is divided into multiple parallel signal paths with different amplification gains. A first signal path includes a first amplifier with high gain for low-level signals, while a second signal path includes a second amplifier with low gain for high-level signals. This segmentation allows each path to be optimized for specific signal levels, preventing overload distortion while maintaining sensitivity.
Solution Approach 2:
The system dynamically switches between different signal paths based on the instantaneous level of the audio signal. A level detector continuously monitors the signal and controls a switch to select the appropriate amplifier path, enabling the system to adapt its gain characteristics in real-time according to signal conditions.
2Speed
If signal switching is performed without zero-crossing detection, then response time is improved, but audible artifacts and distortion are introduced
Solution Approach 1:
The system performs preliminary detection of the zero-crossing point before executing the signal path switch. The level detector identifies when the audio signal crosses zero amplitude, and the switch is triggered at this precise moment. This preliminary timing action ensures that switching occurs when the signal amplitude is minimal, preventing audible artifacts while maintaining fast response.
3Use of energy by moving object
If DC power supply voltage is reduced for portable devices, then power consumption is improved, but dynamic range and signal handling capability deteriorate
Solution Approach 1:
The amplification system is segmented into multiple paths with different gain stages, allowing the use of lower-voltage amplifiers in parallel rather than requiring a single high-voltage amplifier. This enables the system to handle both low-level and high-level signals effectively while operating from reduced DC power supply voltages typical of portable devices.
Solution Approach 2:
The system changes the amplification parameter (gain) dynamically by switching between different amplifier paths. When operating from reduced DC voltages, the system can still achieve the necessary dynamic range by selecting the appropriate gain stage based on signal level, thereby maintaining adaptability despite voltage constraints.
Data Source
AI summary
The present invention relates to an audio signal controller adapted to receiving first and second digital audio signals and estimating a signal feature of the first or second digital audio signal. The estimated signal feature is compared with a predetermined feature criterion and the audio signal controller switches from conveying the first digital audio signal to conveying the second digital audio signal to a controller output, or vice versa, at a zero-crossing of the first digital audio signal or the second digital audio signal based on the comparison between the estimated signal feature and the predetermined feature criterion.