Avionics Network Time Synchronization via Distributed PTP
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Solution Overview
Problem
In avionics networks like ARINC 664, Part 7, ensuring high integrity data transmission requires accurate time synchronization among nodes to maintain safety-critical data integrity, but existing methods consume significant processing resources and network bandwidth.
Innovation Solution
A method for synchronizing local time references at terminal nodes to a global network time using precise time protocol (PTP) messages, where master end systems transmit clock synchronization messages, and slave end systems adjust their local clocks based on received PTP messages, with priority settings to determine which master nodes are used for synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a centralized management function is used to provide time reference and offset tables, then time synchronization accuracy is improved, but processing resources and network bandwidth are significantly consumed
Solution Approach 1:
The patent extracts the time synchronization function from the centralized management architecture and implements it as a distributed protocol among nodes. Each node independently computes its time offset using PTP messages from master nodes, eliminating the need for centralized time reference distribution and offset table management, thereby reducing processing overhead while maintaining synchronization accuracy
Solution Approach 2:
Nodes perform self-synchronization by autonomously computing their time offsets based on PTP messages received from master nodes. Each slave node independently calculates its offset without requiring centralized management intervention, reducing both processing resources at individual nodes and overall network bandwidth consumption compared to centralized offset distribution
2Measurement precision
If offset information is computed and applied at each node, then time synchronization is achieved, but device complexity increases
Solution Approach 1:
The patent changes the approach from centralized parameter distribution to distributed parameter computation. Instead of receiving pre-computed offset values from a management function, each node computes its own time offset parameter dynamically based on PTP message timestamps, simplifying the overall system architecture while maintaining precision
Solution Approach 2:
The PTP protocol implements feedback mechanisms where slave nodes send timing requests and receive synchronized timestamps from master nodes. This feedback loop enables each node to autonomously adjust its time offset based on measured delays, achieving accurate synchronization without complex centralized control logic
3Reliability
If additional low-latency communication paths are created between every node and management function, then time integrity validation is improved, but network bandwidth consumption increases
Solution Approach 1:
The PTP messages serve multiple functions simultaneously: they provide time reference synchronization, enable offset computation, and support integrity validation all through a single communication path. This multi-functionality eliminates the need for separate dedicated channels for each management function, reducing overall network bandwidth consumption while maintaining reliability
Solution Approach 2:
The patent merges the time reference distribution, offset computation, and integrity validation functions into a unified PTP message exchange mechanism. Instead of requiring separate communication paths for each function, all three are achieved through the same master-slave message interactions, thereby reducing network bandwidth requirements while preserving time integrity validation capability
Data Source
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AI summary
A method of synchronizing a local estimation of global network time (LNT) of a receiving node (70, 76, 80, 84, 90, and 94) on a network to a global network time reference (GNT) is provided. The free running nodes (70, 76, 80, 84, 90, and 94) receive precise time protocol synchronization messages and determine a ratio (R) and an offset (TO) based on time data extracted from the messages.