Adaptive Dynamic Range Control for Sigma-Delta Audio Noise
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Solution Overview
Problem
Sigma-delta modulators in audio systems face challenges in maintaining audio quality due to errors in digital bit streams and power, bandwidth limitations, particularly when the oversampling ratio is decreased, leading to increased quantization noise in the audio band.
Innovation Solution
An adaptive dynamic range controller is introduced to adjust the dynamic range of the signal output from the sigma-delta modulator, inversely scaling the signal to reduce audio artifacts and power consumption by filtering the signal based on the instantaneous amplitude of the audio input, thereby minimizing noise in low signal regions and optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the oversampling ratio is decreased to save computational power and transmission bandwidth, then power consumption and bandwidth usage are reduced, but quantization noise increases in the audio band
Solution Approach 1:
The patent implements dynamic range control that adapts the signal processing in real-time based on the instantaneous amplitude of the audio signal. The system dynamically adjusts the gain applied to the quantized signal, applying stronger attenuation during low-amplitude regions where quantization noise is most problematic, and reducing attenuation during high-amplitude regions where the signal dominates the noise floor.
Solution Approach 2:
The system changes the processing parameters dynamically by applying different attenuation levels to the quantized signal based on the detected signal amplitude. The adaptive dynamic range controller modifies the gain parameter in real-time, creating a time-varying filter that optimizes the trade-off between noise reduction and signal fidelity for different amplitude conditions.
2Quantity of substance
If the oversampling ratio is decreased to save transmission bandwidth, then bandwidth usage is reduced, but quantization noise increases in the audio band
Solution Approach 1:
The adaptive dynamic range controller implements time-varying signal processing that adjusts the attenuation applied to the quantized signal based on instantaneous amplitude detection. This dynamic approach allows the system to maintain lower bandwidth usage while selectively reducing quantization noise in low-amplitude regions where it is most audible.
Solution Approach 2:
The system employs parameter modulation by changing the gain applied to the quantized signal in real-time according to the detected signal amplitude. This creates an adaptive bandwidth-efficient transmission system that minimizes quantization noise impact without requiring increased oversampling ratios.
3Reliability
If errors are introduced into the digital bit stream due to processing errors, unreliable storage mediums, or disturbances in the transmission medium, then system robustness decreases, but audio artifacts are generated
Solution Approach 1:
The adaptive dynamic range controller applies preliminary processing to the quantized signal by detecting potential error conditions through amplitude analysis and pre-compensating for their effects. The system applies dynamic attenuation that is particularly aggressive in low-amplitude regions where errors are most likely to manifest as audible artifacts, thereby preventing rather than merely correcting audio quality degradation.
Data Source
AI summary
Apparatus and method for processing signals. A sigma-delta modulator is used. An adaptive dynamic range controller is configured to adaptively adjust the dynamic range of a signal output from the sigma-delta modulator.