Muted Audio Input Switching to Eliminate Pops and Signal Degeneration
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Solution Overview
Problem
Conventional audio switching systems in car entertainment systems often generate switching noise or 'pops' and signal degeneration, which are unacceptable in high-quality stereo audio setups, necessitating a non-obtrusive switching method between multiple audio sources.
Innovation Solution
A system and method that utilize a switch unit and mute units to seamlessly transition between audio sources by muting the current signal and unmuting the new signal using either hard or soft modes based on signal parameters, such as amplitude, to prevent audible disruptions during switching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a simple audio switch is used to switch between audio sources, then the device complexity is reduced and ease of operation is improved, but switching noise or 'pops' and signal degeneration occur
Solution Approach 1:
The system performs preliminary muting of the currently active audio source before switching to a new audio source. This preliminary action prevents switching noise and pops by ensuring the audio output is muted before the switch occurs, eliminating the harmful transient signals that would otherwise be generated during the switching process.
Solution Approach 2:
The patent introduces a mute unit as an intermediary component between the switch unit and the audio output. This mediator controls the muting and unmuting of audio signals, allowing the switch to change audio sources while the mute unit manages the audio level transitions smoothly, preventing direct switching noise from reaching the output.
2Speed
If audio switching is performed without muting, then the switching speed is improved and loss of time is reduced, but audible pops and signal degeneration occur
Solution Approach 1:
The system mutes the current audio source in advance before the switch occurs, and unmutes the new audio source immediately after switching. This preliminary muting action eliminates audible pops while maintaining fast switching, as the muting/unmuting sequence is automatically coordinated with the switching event without requiring manual intervention or causing noticeable delays.
3Object-generated harmful factors
If a mute unit is added to prevent switching noise, then switching noise is eliminated, but the device complexity increases
Solution Approach 1:
The mute unit is integrated with the switch unit into a unified audio switching system. The control logic for muting and unmuting is combined with the switching control, allowing both functions to be managed by a coordinated control mechanism. This merging reduces the overall system complexity compared to having separate, independently controlled muting and switching systems.
Solution Approach 2:
The mute unit serves multiple functions: it mutes the current audio source before switching, it can mute during switching transitions, and it unmutes the new audio source after switching. This multi-functionality reduces the need for additional dedicated components for each function, thereby managing system complexity while achieving comprehensive noise elimination.
4Speed
If hard unmuting mode is used for low amplitude signals, then the switching is faster, but signal quality may be compromised
Solution Approach 1:
The system dynamically selects between hard unmuting mode and soft unmuting mode based on the amplitude characteristics of the audio signal. For low amplitude signals, hard unmuting provides fast switching without compromising perceived quality. For high amplitude signals, soft unmuting prevents distortion and maintains signal quality. This dynamic adaptation optimizes both speed and quality based on real-time signal conditions.
Solution Approach 2:
The unmuting characteristics (slope, duration, amplitude profile) are changed based on the signal parameters being processed. The system adjusts the unmuting parameter profile according to whether the signal is low amplitude or high amplitude, allowing optimal performance for each signal type without requiring separate hardware paths.
Data Source
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AI summary
A system and method for switching between multiple audio input signals to select one of the audio input signals as audio output signal are disclosed which comprise receiving the audio input signals, receiving a control signal, and switching controlled by the control signal from a first one of the audio input signals to a second one of the audio input signals. Prior to switching, the first one of the audio input signals is muted and upon switching, the second one of the audio input signals is unmuted in one of multiple unmute modes dependant on one or more signal parameters characterizing the second one of the audio input signals.