Seafloor Measurement Time Correction Without Continuous Cable Sync
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Solution Overview
Problem
The installation of a large number of measuring apparatuses on the seafloor for seismic exploration using a PTP network with cables increases wiring costs, and clock drift in these apparatuses affects measurement precision, leading to reduced accuracy in sub-seafloor geological structure analysis.
Innovation Solution
A measurement system that includes a data processing apparatus and measuring apparatuses with oscillators for time measurement, which identify and correct time differences between absolute and internal times using acoustic and optical signals at the start and end of measurement periods, allowing precise data analysis without continuous network connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of measuring apparatuses are connected to a PTP network using cables, then accurate time synchronization is achieved, but cable wiring costs increase
Solution Approach 1:
The patent extracts the time synchronization function from the continuous cable-connected PTP network and implements it through periodic acoustic signals transmitted by the ship. This allows measuring apparatuses to obtain accurate time information without requiring permanent cable connections, thereby reducing wiring costs while maintaining time synchronization accuracy.
Solution Approach 2:
The patent introduces acoustic signals as an intermediary medium for time synchronization. Instead of direct cable connections, the ship transmits acoustic signals that serve as time references to multiple measuring apparatuses simultaneously, enabling time synchronization without extensive cable wiring.
2Quantity of substance
If measuring apparatuses operate independently with internal oscillators, then cable wiring costs are reduced, but clock drift affects measurement precision
Solution Approach 1:
The patent applies preliminary action by having the ship periodically transmit acoustic time reference signals to the measuring apparatuses before and during measurement operations. This allows the apparatuses to correct their internal oscillator drift proactively rather than requiring continuous cable connections, maintaining measurement precision while reducing wiring costs.
Solution Approach 2:
The patent implements feedback mechanisms where measuring apparatuses compare their internal oscillator time with the acoustic time reference signals received from the ship. Based on this feedback, the apparatuses can correct their internal timekeeping, compensating for clock drift and maintaining measurement accuracy without continuous cable connections.
3Measurement precision
If continuous network connection is maintained for time synchronization, then measurement accuracy is preserved, but measurement efficiency over extended periods decreases
Solution Approach 1:
The patent employs periodic action by having the ship transmit acoustic time reference signals at regular intervals rather than maintaining continuous cable connections. This periodic synchronization approach preserves measurement accuracy by providing time references when needed, while allowing the measuring apparatuses to operate independently between intervals, thereby improving overall measurement efficiency over extended periods.
Data Source
AI summary
A data processing apparatus has: a data acquiring section that acquires a plurality of pieces of measurement data generated by a measuring apparatus; a time difference identifying section that identifies: a first time difference which is a difference between an absolute start time of a time point when the measurement period has started and the internal time associated with the measurement data obtained at the time point when the measurement period has started and a second time difference which is a difference between an absolute end time of a time point when the measurement period has ended and the internal time associated with the measurement data obtained at the time point when the measurement period has ended; and a correcting section that corrects the internal time associated with the plurality of pieces of measurement data on the basis of the first time difference and the second time difference.