10BASE-T1S Clock Sync Using Topology Discovery Delay
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Solution Overview
Problem
Current methods for determining propagation delay in 10BASE-T1S multidrop networks are inadequate, as they rely on fixed estimates based on cable distance, failing to account for network changes over time, such as addition or removal of nodes, and are unsuitable for precise time synchronization.
Innovation Solution
Utilize propagation delay measurements from topology discovery to dynamically update the clock in a 10BASE-T1S mixing segment, using precision time protocol messages and pulse counting to accurately determine and save the propagation delay, enabling precise clock synchronization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed propagation delay estimates based on cable distance are used, then device complexity is reduced, but time synchronization precision deteriorates
Solution Approach 1:
The patent performs propagation delay measurement during the topology discovery phase, which occurs before normal network operation. This preliminary measurement captures the actual delay characteristics of the network topology, enabling precise time synchronization without adding complexity to the ongoing synchronization process. The measured delay values are stored and reused for clock updates.
Solution Approach 2:
The network nodes perform self-measurement of propagation delay using standard PTP messages already exchanged during topology discovery. Each node uses its own clock and processing capabilities to measure the round-trip delay, eliminating the need for external measurement equipment or complex centralized control systems.
2Adaptability or versatility
If fixed propagation delay values are used, then adaptability to network changes is reduced, but measurement precision requirements are lowered
Solution Approach 1:
The patent implements dynamic propagation delay measurement by repeatedly measuring delay during topology discovery events. When nodes are added or removed from the network, the topology discovery is triggered, and new propagation delay values are measured and updated. This ensures the synchronization system always uses current, accurate delay values adapted to the actual network configuration.
3Measurement precision
If PDelay_response and PDelay_followup messages are used for propagation delay measurement, then time synchronization precision is improved, but device complexity increases due to multidrop topology challenges
Solution Approach 1:
The patent reuses the existing topology discovery message exchange mechanism for the dual purpose of both topology identification and propagation delay measurement. The same PTP messages (Sync, Follow_Up, Delay_Request, Delay_Response) that are already part of the 10BASE-T1S topology discovery protocol are utilized to obtain accurate delay values, eliminating the need for separate measurement protocols or message types.
Data Source
AI summary
A system and method for the use of propagation delay from topology discovery to update a clock in a 10BASE-T1S mixing segment are disclosed. The method may include determining a propagation delay. The propagation delay may be an amount of time for a signal to be received by a node after the signal is sent by a reference node. The method may also include receiving, at the node, a first message from the reference node after determining the propagation delay. The method may additionally include receiving, at the node, a second message from the reference node, the second message indicating a time the first message was sent. The method may include recording, at the node, a first timestamp indicating a time at which the first message is received. The method may further include updating a clock of the node using the first timestamp, the second message, and the propagation delay.