Adaptive Blend Algorithm for In-Band On-Channel Radio Audio
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing digital radio receivers experience frequent and annoying blending between analog and digital audio streams due to inadequate signal quality assessment and alignment, leading to degraded audio quality and reduced digital coverage.
Innovation Solution
An adaptive blend algorithm that employs filtered Digital Signal Measure (DSM) estimates, recent blend penalties, and recovery rates to dynamically adjust thresholds, minimizing blends and maintaining analog audio over intermittent digital signals, especially in hybrid HD Radio systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing blend algorithms are used to transition between analog and digital audio streams, then digital audio coverage is extended, but frequent and annoying blending occurs leading to degraded audio quality
Solution Approach 1:
The patent implements dynamic threshold adjustment where the analog-to-digital threshold is increased after a blend event occurs. This adaptive mechanism prevents frequent switching by making the system respond to sustained signal quality improvements rather than transient variations, thereby reducing annoying blending while maintaining digital coverage extension.
Solution Approach 2:
The system monitors blend events and uses this feedback to adjust future blend decisions. When blending occurs, the threshold for returning to digital mode is raised, creating a feedback loop that stabilizes the audio output and prevents oscillation between analog and digital streams, thus improving audio quality reliability.
2Area of stationary object
If blend thresholds are lowered to extend digital coverage, then more areas receive digital signal, but blending occurs more frequently causing choppy transitions
Solution Approach 1:
The threshold dynamically adapts based on operational history rather than remaining fixed. After blending occurs, the analog-to-digital threshold increases, creating a hysteresis effect that stabilizes transitions and prevents choppy audio even in extended coverage areas where signal conditions may be marginal.
Solution Approach 2:
The system prepares for potential instability by raising the threshold after blending, creating a cushion against premature re-blending. This anticipatory adjustment ensures that even in extended coverage areas, the system maintains stable operation by requiring sustained signal quality improvement before switching back to digital mode.
3Reliability
If frequent blending is used to maintain audio continuity, then signal outages are mitigated, but audio quality degrades due to multiple transitions
Solution Approach 1:
The system uses feedback from blend events to adjust thresholds, preventing unnecessary re-blending. This feedback mechanism maintains signal continuity by ensuring that once analog mode is entered, the system remains there until signal quality substantially improves, thereby reducing transition-related quality degradation while still providing continuity protection.
Solution Approach 2:
The dynamic threshold adjustment creates an adaptive response that balances continuity and quality. By making the threshold history-dependent, the system provides sufficient blending to maintain continuity during outages while preventing excessive transitions that would degrade audio quality through repeated switching.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for processing a digital audio broadcast signal in a radio receiver includes: receiving a digital audio broadcast signal; demodulating the digital audio broadcast signal to produce an analog audio stream and a digital audio stream; determining a digital signal quality value for the digital audio stream; blending an output of the radio receiver from the analog audio stream to the digital audio stream when the digital signal quality value exceeds an adaptive analog-to-digital threshold value; and blending the output of the radio receiver from the digital audio stream to the analog audio stream when the digital signal quality value falls below an adaptive digital-to-analog threshold value, wherein the adaptive digital-to-analog threshold value is lower than the adaptive analog-to-digital threshold value.