Stereo Bit Clock Tuning for Bluetooth Audio Phase Synchronization
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Solution Overview
Problem
Wireless distribution of real-time audio signals using Bluetooth technology faces challenges in maintaining phase synchronization between multiple sink devices, leading to potential phase variations and detrimental effects on the audio experience, especially in applications like headsets where precise timing is crucial.
Innovation Solution
A system and method that include a source communication device generating and transmitting time stamps incorporating both network and streaming clock values, allowing sink devices to adjust their streaming clocks to align with the source, using a time stamp mechanism that extrapolates future clock values and provides indications of subsequent time stamps to ensure synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wireless distribution of real-time audio signals is implemented using Bluetooth technology, then audio transmission between devices is enabled, but phase synchronization between multiple sink devices deteriorates leading to phase variations
Solution Approach 1:
The source device generates and transmits time stamps containing network clock values before audio data transmission. These time stamps serve as preliminary synchronization references that enable sink devices to pre-adjust their streaming clocks to match the source device's clock, thereby preventing phase variations during audio playback
Solution Approach 2:
The system implements a feedback mechanism where sink devices receive time stamps from the source device, compare their local streaming clock values with the source streaming clock values in the time stamps, and adjust their streaming clocks based on the comparison results. This closed-loop feedback ensures continuous phase synchronization across multiple sink devices
2Manufacturing precision
If time stamp generation and transmission is implemented, then clock synchronization between source and sink devices is improved, but device complexity increases
Solution Approach 1:
The time stamp mechanism serves multiple functions simultaneously: it carries network clock values for synchronization, provides timing references for audio playback, and enables buffer management. By consolidating these functions into a single time stamp structure, the patent reduces overall system complexity despite adding synchronization capabilities
Solution Approach 2:
Time stamps act as an intermediary carrier that bridges the source device and sink devices for clock synchronization. Rather than implementing complex direct clock linking between devices, the time stamp intermediary conveys timing information, simplifying the synchronization architecture while maintaining precision
3Manufacturing precision
If streaming clock adjustment is implemented based on time stamp comparison, then phase synchronization is maintained, but processing time increases
Solution Approach 1:
Sink devices continuously monitor and compare their streaming clock values with source streaming clock values from received time stamps before audio playback begins. This preliminary clock alignment ensures that when audio data is transmitted, both devices are already synchronized, minimizing the need for time-consuming adjustments during playback
Solution Approach 2:
The system maintains continuous clock synchronization by periodically exchanging time stamps and adjusting streaming clocks throughout the audio transmission process. This continuous action prevents drift accumulation, ensuring phase alignment is maintained without requiring large, time-consuming corrections
Data Source
AI summary
A source communication device includes a source network clock to control timing of communicating with other devices in a network, a source streaming clock associated with processing of audio or video data, a time stamp generator to generate a time stamp that includes a source network clock value and a source streaming clock value, and a time stamp insertion mechanism that incorporates the time stamp into a data unit that is to be transmitted to one of the other devices in the network. A sink communication device includes a sink network clock synchronized with the source network clock, a sink streaming clock associated with processing of audio or video data, and a sink time stamp mechanism to compare a sink streaming clock value with the source streaming clock value, and adjust the sink streaming clock based on the comparison.