Offline Timestamp Correction for Network Clock Drift
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Solution Overview
Problem
Existing clock synchronization methods introduce clock drifts and timing errors by adjusting clocks at event recordation times, leading to runaway inaccuracies.
Innovation Solution
The method involves post-adjustment of event timestamps offline to implement virtual time synchronization among detection node clocks, avoiding clock adjustments at event recordation times.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If clocks are adjusted at event recordation times to achieve time synchronization, then timestamp accuracy at recordation is improved, but clock drifts and timing errors are introduced over time
Solution Approach 1:
The patent applies preliminary action by determining clock offsets between detection nodes in advance, before events occur. The system performs offset determination operations periodically or continuously to establish reference offset values that are stored and later used to correct timestamps offline, rather than adjusting clocks at the moment of event recordation.
Solution Approach 2:
The patent inverts the conventional approach by not adjusting clocks at recordation time, but instead adjusting timestamps after events have been recorded. The system determines clock offsets and uses these to correct timestamps in an offline manner, reversing the traditional sequence of clock synchronization and event recording.
2Loss of time
If clock adjustments are made frequently to maintain synchronization, then time accuracy is improved, but timing errors and drifts accumulate
Solution Approach 1:
The system performs offset determination operations periodically or continuously in advance to establish reference offset values. These pre-determined offsets are stored and later applied to correct timestamps offline, avoiding the need for frequent clock adjustments that would introduce timing errors.
Solution Approach 2:
The patent uses offset records that capture clock offset information at specific times. These offset records serve as copies of the clock state at determination times, which are then used to correct timestamps from events that occurred at different times, allowing accurate timestamp interpretation without actual clock adjustments.
3Measurement precision
If timestamps are corrected in real-time at detection nodes, then synchronization is improved, but system complexity and potential for error introduction increase
Solution Approach 1:
The patent extracts the timestamp correction function from the detection nodes and moves it to an offline processing stage. Detection nodes simply record events with their local timestamps and store offset records, while the actual timestamp correction is performed later using stored offset information, separating the recording function from the synchronization function.
Solution Approach 2:
The patent introduces offset records as an intermediary between clock determination and timestamp interpretation. These offset records capture the relationship between detection node clocks and reference time at specific moments, serving as a mediator that allows accurate timestamp interpretation without requiring active clock synchronization or real-time adjustments.
Data Source
AI summary
A method and system for the post-adjustment (i.e., offline) of event timestamps to implement virtual time synchronization amongst detection node clocks. In existing methodologies with the goal of clock synchronization, clocks (and timestamps generated therefrom) are disciplined or adjusted at the recordation time of the events on a detection node (e.g., a switch/router, an Internet-of-Things (IoT) device, a wireless sensor, etc.). However, there is no particular reason for these clocks or timestamps to be accurate during the recordation time, but rather, should be accurate at their use or interpretation time. Further, through these recordation time adjustments, clock drifts and timing errors may be gradually introduced, leading to runaway inaccuracies. The disclosed method and system intentionally avoids the disciplining of clocks at event recordation times on the detection node and, instead, adjusts timestamps during interpretation times, to overcome the aforementioned issues.