Audio Clock Synchronization via Network Time Correlation
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Solution Overview
Problem
Networked audio devices often experience synchronization issues due to differing clock signals, particularly between the computing device's D/A converter and network interfaces, leading to time offsets and drift, which affect the synchronization of audio speakers connected via wires or wireless LANs.
Innovation Solution
Implementing a synchronization routine that reads and correlates counters representing the time of the network and audio device clocks, using IEEE standard 802.1AS, to adjust the audio clock and ensure synchronization across all connected speakers, both physically and wirelessly, through sample rate conversion and clock adjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple independent clock sources are used for network interfaces and audio devices, then device functionality and independence are improved, but clock synchronization and timing accuracy deteriorate
Solution Approach 1:
The patent introduces a master clock as an intermediary reference that both network interfaces and audio devices use to synchronize their operations. This master clock acts as a mediator that coordinates timing across all components, allowing them to maintain independent functionality while achieving synchronized operation through the common reference.
Solution Approach 2:
The system implements feedback mechanisms where clock counters are continuously monitored and compared across different devices. The synchronization routine reads counters from multiple sources, calculates time offsets, and adjusts timing parameters based on the measured deviations, creating a closed-loop control system that maintains synchronization.
2Device complexity
If separate clock signals are used for network and audio hardware, then hardware independence is improved, but time offset and drift increase
Solution Approach 1:
The patent employs dynamic sample rate conversion that can adjust in real-time based on measured clock drift and time offsets. The system continuously monitors the relationship between network and audio clocks and dynamically modifies sampling parameters to compensate for frequency differences, maintaining synchronization despite hardware independence.
Solution Approach 2:
The synchronization system changes operational parameters such as sample rates, buffer sizes, and timing intervals based on the measured state of clock synchronization. When drift or time offsets are detected, the system adjusts these parameters to realign the timing between network and audio subsystems.
3Measurement precision
If real-time clock correlation is implemented across multiple devices, then synchronization accuracy is improved, but system complexity increases
Solution Approach 1:
The patent divides the synchronization system into separate functional modules: a master clock generation unit, individual device clock units, a counter reading and correlation module, and a parameter adjustment module. Each module performs a specific function, making the overall complex system manageable through functional segmentation and independent optimization of each component.
Data Source
AI summary
Techniques are disclosed for synchronizing multiple clock sources of a system, and may include: determining time of a first clock at a first and second time instants; determining time of a second clock at a third time instant occurring between the first and second time instants, and a fourth time instant occurring after the second time instant; and determining a clock offset between the first and second clocks based on the determined times. The first and/or second clocks may be adjusted based on the clock offset to synchronize clock operation. This adjusting can be used, for instance, to synchronize operation of an audio and/or video component operating according to the first clock with an audio and/or video component operating according to the second clock. The techniques may further include determining if the clock offset is valid (e.g., based on detection of perturbing events or difference between a clock's times).