Seismic Node Clock Drift Correction via Polynomial Curve Fitting
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Solution Overview
Problem
Seismic nodes experience clock drift due to aging and temperature changes, leading to inaccuracies in time referencing of recorded seismic data, which existing linear correction methods fail to accurately address.
Innovation Solution
A method involving multiple clock drift measurements before and after deployment, with data fitting to a 2nd order polynomial to create a more accurate clock drift correction function, reducing timing errors and improving seismic survey data quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear correction function is used for clock drift, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent changes the mathematical model parameters from a linear function (first order) to a polynomial function (second order or higher). This parameter change in the correction function's complexity allows for more accurate representation of non-linear clock drift behavior, achieving up to 1000 times improvement in timing accuracy while accepting increased computational complexity.
2Measurement precision
If more clock drift measurements are performed, then measurement precision improves, but loss of time increases
Solution Approach 1:
The patent performs multiple clock drift measurements at predetermined time points before deploying the seismic node to the seabed. This preliminary action allows the system to establish a polynomial correction function in advance, reducing the need for extensive measurements after deployment and minimizing the loss of measurement time during actual seismic recording operations.
3Measurement precision
If expensive slave clocks are used, then measurement precision improves, but cost increases
Solution Approach 1:
The patent enables the use of less expensive slave clocks by compensating for their lower inherent precision through a more sophisticated polynomial correction function. Instead of relying on expensive high-precision clocks, the system uses multiple measurements and mathematical correction to achieve the same or better timing accuracy, effectively replacing expensive hardware with a combination of cheaper hardware and software processing.
Data Source
AI summary
A method of correcting clock drift in at least one slave clock in a seismic node. The method comprises obtaining a number of clock drift measurements of the at least one slave clock in the at least one seismic node. A clock drift correction function as a function of time is calculated by curve fitting the number of clock drift measurements to a 2nd order polynomial. A time of reference of the recorded seismic sensor data is corrected by the 2nd order polynomial clock drift correction function.