Underwater EM Measurement Using ADCP Noise Cancellation
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Solution Overview
Problem
Existing technologies face challenges in accurately measuring and compensating for electromagnetic noise caused by ocean dynamics, such as waves and currents, which affects the accuracy of electromagnetic field measurements in coastal regions.
Innovation Solution
The use of an apparatus comprising acoustic Doppler current profilers (ADCPs) and magnetometers, with computer code for processing data to perform least squares calculations, allowing for the reduction of electromagnetic noise by correlating ADCP time series data with magnetometer time series data, thereby minimizing the error between the two.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electromagnetic field measurements are conducted in coastal regions, then oceanographic data can be collected, but electromagnetic noise from ocean dynamics (waves, currents) degrades measurement accuracy
Solution Approach 1:
The patent introduces an intermediary system consisting of ADCP sensors and computational algorithms that measure ocean dynamics (currents, waves) and use this information to model and subtract the induced electromagnetic noise from magnetometer measurements. This mediator approach allows the system to account for and remove the harmful electromagnetic interference generated by seawater motion through the Earth's magnetic field.
Solution Approach 2:
The system implements feedback by continuously monitoring ocean dynamics via ADCP sensors and using this real-time data to adjust and correct magnetometer measurements. The measured oceanographic parameters feed into a noise model that generates correction signals, which are then applied to the electromagnetic field measurements, creating a closed-loop system that adaptively compensates for noise.
2Measurement precision
If ADCP and magnetometer data are processed using least squares calculations, then electromagnetic noise can be reduced, but computational complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-processing the ADCP and magnetometer data through synchronization and filtering operations before the least squares calculation. The system prepares the time series data by aligning timestamps, applying appropriate filters, and organizing the data structures in advance, which simplifies the subsequent noise reduction computation and makes the complex least squares algorithm more tractable.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces electromagnetic noise, enabling more accurate measurements of underwater electromagnetic fields and improving the understanding of ocean dynamics' influence on electromagnetic fields, as demonstrated by preliminary results showing correlation between ADCP-predicted and measured magnetic fields.
Implementation Method 1
acoustic Doppler current profilers (ADCPs)
Implementation Method 2
magnetometers
Implementation Method 3
The motion of the electrically conductive water through the earth's magnetic field causes an important source of extremely low frequency electromagnetic (EM) variations in the ocean. Movement of seawater in the earth's magnetic field produces an electromotive force with an associated electric current and magnetic field.
Data Source
AI summary
According to exemplary inventive practice, an ADCP system (including one or more acoustic Doppler current profilers) and a magnetometer system (including one or more magnetometers) are placed underwater. The ADCP system is used to obtain ADCP time series data. The magnetometer system is used to obtain magnetometer time series data. A computer performs computations with respect to input from the ADCP system and input from the magnetometer system. The computations include formulation of a least squares matrix to minimize a least squared error between the ADCP time series data and the magnetometer time series data. The present invention may be practiced, for instance, whereby a magnetometer is centrally located in relation to a triangular arrangement of three ADCPs, or whereby the ADCP system and the magnetometer system are co-located.