Network Time Synchronization Using Physical-Layer Clock Recovery
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing time synchronization methods, such as NTP, PTP, WhiteRabbit, and GNSS, face challenges in achieving precise and reliable time synchronization due to limitations in protocol complexity, hardware requirements, and environmental vulnerabilities.
Innovation Solution
A time synchronization device and network that utilize a time-estimating device to synchronize with non-time-estimating devices, employing a communication section, clock section, frequency comparison sections, and estimation processing to achieve high-precision time synchronization without dedicated ICs and satellite radio waves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If NTP or PTP protocols are used for time synchronization, then a large number of nodes can be synchronized with simple configuration, but precise time synchronization cannot be achieved
Solution Approach 1:
The patent replaces application-layer protocol-based time synchronization (NTP/PTP) with a physical-layer frequency comparison mechanism. By comparing clock frequencies directly at the physical layer and using phase-locked loops to synchronize clock signals, the system achieves nanosecond-level precision while maintaining configuration simplicity. The frequency comparison section and phase synchronization section enable direct physical-layer synchronization without complex protocol stacks.
2Measurement precision
If WhiteRabbit is used for precise time synchronization, then high accuracy of several nanoseconds is achieved, but a dedicated IC is required in each node making the system complicated
Solution Approach 1:
The patent creates a universal time synchronization mechanism that can be implemented using standard communication interfaces and clock circuits already present in most digital systems. The frequency comparison section can utilize existing PLL circuits and clock generators, eliminating the need for dedicated WhiteRabbit ICs. The system achieves similar nanosecond-level accuracy using components that are part of standard digital system architecture.
3Measurement precision
If GNSS is used for time synchronization, then precise time information is provided by satellite radio waves, but the system is vulnerable to antenna failure, solar wind deterioration, and jamming
Solution Approach 1:
The patent introduces a local frequency comparison and phase synchronization mechanism as an intermediary between external time sources and node clocks. The frequency comparison section locally compares frequencies and the phase synchronization section maintains phase coherence, creating a resilient synchronization system that does not depend on vulnerable satellite radio wave reception. This intermediary mechanism provides continuous synchronization even when GNSS signals are unavailable or jammed.
Data Source
AI summary
A node includes: a communication module that recovers a clock signal of another node; a high-precision clock module; a first phase/frequency comparison module; a time estimation section that estimates time information of each node; a counter value correction section that corrects a counter value; a fractional PLL; a second phase/frequency comparison module; and a division ratio correction section that corrects a division ratio of the fractional PLL.