Ethernet PHY Clock Synchronization for Low-Latency Media Clocks
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Solution Overview
Problem
High-definition real-time networked audio applications, such as car road noise cancellation, are adversely affected by high clock synchronization and latency, necessitating improved synchronization accuracy and reduced latency in clock synchronization processes.
Innovation Solution
Implementing hardware-based solutions for generating and decoding clock reference packets with time stamps, utilizing Ethernet PHY circuitry that includes packet decoder, reference clock generator, and media clock generator to synchronize local reference clocks and generate media clocks with reduced latency and improved accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If software-based clock synchronization methods are used, then device complexity is reduced, but synchronization accuracy and latency performance deteriorate
Solution Approach 1:
The patent replaces software-based clock synchronization mechanisms with dedicated hardware circuits including a packet decoder circuit, reference clock generator, control circuit, and media clock generator. This hardware implementation directly processes clock reference packets and generates synchronized media clocks without software intervention, achieving sub-millisecond synchronization accuracy required for real-time audio applications while the modular circuit design keeps complexity manageable
Solution Approach 2:
The synchronization system is divided into separate functional hardware modules: packet decoder circuitry for extracting timing information, reference clock generator for producing base clock signals, control circuitry for coordinating operations, and media clock generator for producing final synchronized clocks. This segmentation allows each component to be optimized independently and facilitates precise timing control throughout the signal path
2Loss of time
If traditional clock synchronization methods are used, then ease of operation is maintained, but latency increases adversely affecting real-time audio applications
Solution Approach 1:
The reference clock generator continuously generates reference clock signals in advance, and the packet decoder circuit continuously monitors incoming clock reference packets. When a packet arrives, the timing information is immediately processed to adjust the media clock generator, eliminating delays associated with periodic polling or software-based timing adjustments. This preliminary readiness enables immediate response to timing changes
Solution Approach 2:
The patent replaces software-based timing operations with dedicated hardware circuits that operate autonomously at the hardware level. The control circuit directly coordinates the packet decoder, reference clock generator, and media clock generator without software mediation, reducing processing latency while maintaining straightforward operation through hardware-level automation
Data Source
AI summary
An apparatus includes: packet decoder circuitry; reference clock generator; control circuitry; and a media clock generator. A first terminal of the reference clock generator is coupled to a second terminal of the packet decoder circuitry. A first terminal of the control circuitry is coupled to a second terminal of the packet decoder circuitry. A second terminal of the control circuitry is coupled to a first terminal of the reference clock generator. A third terminal of the control circuitry is coupled to a second terminal of the reference clock generator. A first terminal of the media clock generator is coupled to the second terminal of the reference clock generator. A second terminal of the media clock generator is coupled to a fourth terminal of the control circuitry.