Audio Synchronous Circuit for Wireless Speaker Time Alignment
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Solution Overview
Problem
Existing audio playback systems using wireless networks face synchronization issues due to differing oscillator responses to temperature, leading to asynchronous playback across loudspeakers, and existing synchronization methods like PTP and WiFi TSF fail to accurately synchronize audio signals.
Innovation Solution
An audio synchronous circuit and method utilizing a synchronous control circuit, WiFi TSF conversion, I2S TSF timer, and processing circuit to compensate for frequency offsets, ensuring accurate time synchronization by adjusting digital audio clock frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If wireless network transmission is used to eliminate wiring, then ease of operation is improved, but time synchronization precision deteriorates due to different oscillator responses to temperature
Solution Approach 1:
The patent changes the timing parameters by using fixed hardware circuit delays instead of software processing delays. The synchronous control circuit generates control signals at predetermined timing points, and the playback timing is determined by hardware circuit characteristics rather than software execution time, which varies with temperature and oscillator frequency
Solution Approach 2:
The patent replaces the software-based timing mechanism with a hardware-based synchronous control circuit. The synchronous control circuit uses fixed physical circuit delays and predetermined timing points to generate control signals, substituting the unreliable software timing (which depends on oscillator frequency) with stable hardware timing
2Reliability
If PTP or WiFi TSF synchronization methods are used, then time synchronization is attempted, but reliability deteriorates due to unpredictable software processing delays and channel competition
Solution Approach 1:
The patent replaces software-based synchronization protocols (PTP, WiFi TSF) with a hardware-based synchronous control circuit that generates control signals at predetermined timing points. This eliminates the unpredictable software processing delays and channel competition effects that plague the previous methods
Solution Approach 2:
The host device's synchronous control circuit autonomously generates control signals based on predetermined timing points and fixed circuit delays. The system serves itself by using the known fixed delay characteristics of its own hardware circuits to calculate accurate playback timing without needing complex synchronization protocols
3Adaptability or versatility
If software processing and channel competition are involved in synchronization, then adaptability is improved, but time precision deteriorates due to indeterminate delays
Solution Approach 1:
The patent changes the fundamental approach by using fixed hardware circuit delays as known parameters. The synchronous control circuit operates at predetermined timing points with fixed delays, transforming the indeterminate software delays into known, measurable hardware characteristics that can be compensated for accurately
Data Source
AI summary
Disclosed are an audio synchronous circuit and an audio synchronous method. The audio synchronous circuit receives at least one beacon packet to generate WiFi time synchronization function (TSF) data, compares the WiFi TSF data with I2S TSF data according to a synchronous control signal to obtain a frequency offset, and compensates a digital audio clock according to the frequency offset. Thus, the audio synchronous circuit can adjust a frequency of the digital audio clock according to the frequency offset to complete synchronization with a transmitter, to avoid unpredictable delays caused by software processing and wireless channel competition, and achieve the purpose of more accurate time synchronization.