Seismic Node Oscillator Calibration via Periodic Reference
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Solution Overview
Problem
Marine seismic exploration faces challenges in maintaining accurate seismic data recording due to oscillator drift caused by temperature changes and other environmental factors, leading to power inefficiency and reduced survey duration, especially with autonomous seismic nodes deployed underwater for extended periods.
Innovation Solution
The use of a seismic node system that incorporates a primary oscillator calibrated by a reference oscillator, such as an atomic or oven-controlled crystal oscillator, with a processor to repeatedly calculate and adjust the frequency calibration, allowing for high precision data recording while minimizing power consumption by intelligently starting and stopping the reference oscillator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a high-precision reference oscillator (atomic or oven-controlled crystal) is continuously operated to maintain frequency stability, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The reference oscillator is operated periodically rather than continuously. The system includes a controller that activates the reference oscillator at predetermined intervals to perform frequency calibration of the primary oscillator, then deactivates it. This periodic operation maintains the required measurement precision while dramatically reducing power consumption during the extended underwater deployment period.
2Duration of action of moving object
If the seismic node operates autonomously for extended periods (days, weeks, or months), then productivity is improved, but oscillator drift causes time errors that reduce measurement precision
Solution Approach 1:
The system performs preliminary frequency calibration by comparing the primary oscillator against the reference oscillator at predetermined intervals during deployment. This preliminary action detects and corrects frequency drift before it accumulates into significant time errors, thereby maintaining measurement precision throughout the extended deployment duration.
Solution Approach 2:
The system implements a feedback mechanism where the controller continuously monitors the frequency of the primary oscillator and compares it against the reference oscillator. When drift is detected, the system automatically adjusts the primary oscillator's frequency to correct the error, ensuring time accuracy is maintained throughout the extended deployment period.
3Measurement precision
If the primary oscillator frequency is continuously calibrated against the reference oscillator, then measurement precision is improved, but power consumption increases
Solution Approach 1:
Frequency calibration is performed periodically at predetermined intervals rather than continuously. The controller activates the reference oscillator only when calibration is needed, compares frequencies, applies corrections to the primary oscillator, then deactivates the reference oscillator. This periodic calibration approach maintains frequency accuracy while minimizing power consumption during long-term autonomous operation.
Data Source
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AI summary
The invention relates to a seismic node (100), comprising at least one seismic sensor with associated electronics, a primary oscillator (106) for timing sensor signals, a reference oscillator (104), a memory, a power source, a switch (102) for turning the reference oscillator on and off, and a processor (112) for digitizing sensor signals and storing them in the memory, calibrating a frequency of the primary oscillator (106) based on the frequency of the reference oscillator (104), and turning the reference oscillator on and off.