Asynchronous Video Transport Clock Synchronization
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Solution Overview
Problem
Existing methods for asynchronous audio/video transport in distributed architectures, such as Hybrid Fiber Cable networks, face challenges in synchronizing clocks between data sources and client devices, leading to clock discrepancies that result in data packet loss, interruptions, and excessive jitter.
Innovation Solution
A remote device, like a remote PHY device, adjusts the clock rate by inserting or deleting null packets in the data stream to equalize the source clock with the internal clock, using techniques like delta clock reference value determination and frequency offset estimation to minimize jitter and ensure seamless synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clock rate adjustment is performed by inserting or deleting packets, then clock synchronization between source and client devices is improved, but data packet loss and interruptions occur
Solution Approach 1:
The patent introduces a remote device as an intermediary component between the data source and client devices. This remote device performs clock rate adjustment by inserting or deleting packets in the data stream, acting as a mediator that resolves the clock frequency mismatch without requiring direct modification at the source or client ends. The intermediary handles the packet insertion/deletion operations to equalize clock rates while maintaining data integrity.
Solution Approach 2:
The patent dynamically adjusts the clock rate parameter by modifying the data stream characteristics. Specifically, it changes the packet transmission rate by inserting null packets or deleting packets based on the clock frequency difference between source and client devices. This parameter adjustment allows the system to adapt to different clock rates while maintaining synchronization.
2Stability of the object's composition
If null packets are inserted or deleted to equalize clock rates, then jitter is reduced, but data stream integrity is compromised
Solution Approach 1:
The patent uses null packets as placeholders or copies that carry clock synchronization information without containing actual data content. These null packets are inserted into the data stream to maintain timing and synchronization without replacing or losing actual data packets. The null packets serve as temporal markers that preserve data stream integrity while enabling clock rate adjustment.
Solution Approach 2:
The patent extracts or removes specific packets from the data stream based on their type and content. By selectively deleting non-critical packets or replacing them with null packets, the system adjusts the data stream rate to match clock frequencies while preserving the integrity of essential data packets. This extraction process allows for controlled modification of the data stream.
3Adaptability or versatility
If packet insertion/deletion is used for clock adjustment, then adaptability to different clock rates is improved, but device complexity increases
Solution Approach 1:
The patent divides the clock synchronization function into separate modular components within the remote device. The packet insertion mechanism, packet deletion mechanism, and clock rate calculation are implemented as distinct functional blocks. This segmentation allows each component to be independently optimized and managed, reducing overall system complexity while maintaining high adaptability to different clock rates.
Data Source
AI summary
A method includes a method includes obtaining source data from a data source, the source data may correspond to a source clock and may be stored in a data buffer. The method may also include performing a clock adjustment to a determined clock. The determined clock may be associated with a data stream output from the data buffer. The clock adjustment may be operable to equalize the source clock and the determined clock. The method may include identifying a symbol clock associated with a buffer device. The method may also include adjusting an amount of null packets in the data stream, in response to a number of elements in the buffer device satisfying a threshold amount in the buffer device. The method may include updating clock reference values present in the source data such that a client device may synchronize with the source data with minimal clock jitter.