Adaptive Audio Blend Transition for In-Band On-Channel Radio
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Solution Overview
Problem
In In-Band On-Channel radio systems, frequent transitions between analog and digital audio signals due to signal outages can be annoying, especially when the audio quality differences are significant, as the current blend transition time is limited and does not effectively match the digital and analog signal characteristics.
Innovation Solution
The method involves separating the analog and digital audio portions of the signal, detecting errors in the digital audio, and adjusting the digital audio's stereo separation and bandwidth to produce an adjusted digital audio portion that is blended with the analog audio, allowing for smoother transitions by setting it to monaural, adding noise, or attenuating it, thereby mitigating the annoyance of frequent blends.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the blend transition time is limited to less than one second due to diversity delay and receiver decoding times, then the system can respond quickly to digital signal availability, but frequent transitions between analog and digital audio become annoying when audio quality differences are significant
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the blend transition time based on signal quality and operating conditions. When digital signal errors are detected or during frequent transition scenarios, the system extends the blend transition time beyond the typical less than one second limit, smoothing the transition to reduce listener annoyance while maintaining quick response capability under normal conditions
Solution Approach 2:
The system implements dynamics by making the blend transition time adaptive rather than fixed. The transition time varies based on real-time detection of digital signal quality, error rates, and operational context, allowing the system to optimize between fast response and smooth transition characteristics depending on current conditions
2Reliability
If the digital audio signal is used whenever available, then higher audio quality is achieved, but frequent transitions to analog backup during outages create listening discomfort
Solution Approach 1:
The patent applies preliminary action by detecting digital signal errors and initiating blend transitions in advance before complete digital signal failure occurs. By detecting errors during the diversity delay time and preparing the analog signal for blending before the digital signal becomes completely unavailable, the system smooths the transition and reduces the abruptness that causes listening discomfort
Solution Approach 2:
The system uses an intermediary blend function that mediates between the digital and analog audio signals. This blend function acts as a buffer, gradually transitioning from digital to analog (or vice versa) rather than making abrupt switches, thereby reducing the harmful effect of frequent transitions while maintaining reliable audio availability
Data Source
AI summary
A method for processing a composite digital audio broadcast signal to mitigate intermittent interruptions in the reception of the digital audio broadcast signal, the method comprising the steps of separating an analog audio portion of the digital audio broadcast signal from a digital audio portion of the digital audio broadcast signal, detecting errors in the digital audio portion of the digital audio broadcast signal, adjusting the digital audio portion of the digital audio broadcast signal in response to errors in the digital audio portion of the digital audio broadcast signal to produce an adjusted digital audio portion, and blending the analog audio portion with the adjusted digital audio portion to produce an audio output. A receiver that performs the method is also included.