Coaxial Coplanar Reference Coil Assembly for Motion Noise Decoupling
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Solution Overview
Problem
The semi-airborne electromagnetic survey system has limited detection depth and accuracy due to high motion noise, particularly same-frequency motion noise and attitude errors, which are not effectively addressed by conventional uniaxial and three-axis measurement methods.
Innovation Solution
A semi-airborne electromagnetic survey device utilizing a coaxial coplanar mutual reference coil assembly, where a reference coil with low sensitivity and small diameter distinguishes additive motion noise, and a measuring coil with higher sensitivity distinguishes both vertical magnetic field signals and motion noise, allowing for their decoupling and cancellation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If uniaxial measurement is used, then device complexity is reduced and weight is decreased, but motion noise at the same frequency as detection signal cannot be suppressed
Solution Approach 1:
The receiving system is segmented into two independent coils: a measuring coil for detecting magnetic field signals and a reference coil for measuring motion noise. This segmentation allows each coil to be optimized for its specific function while maintaining overall system simplicity.
Solution Approach 2:
The reference coil acts as an intermediary that measures the motion noise separately, which then serves as a reference signal for suppressing the same-frequency noise in the measuring coil through post-processing.
2Measurement precision
If three-axis measurement is used, then motion noise suppression is improved, but device complexity and weight increase
Solution Approach 1:
Instead of using a complex three-axis measurement system, the invention segments the function into two separate coils: one for magnetic field detection and another for motion noise reference, achieving noise suppression without three-axis complexity.
Solution Approach 2:
The motion noise measurement function is extracted from the magnetic field detection function, placing it in a separate reference coil. This allows motion noise to be measured and suppressed without requiring three-axis measurement capabilities.
3Productivity
If the receiving coil moves in air, then survey speed and adaptability to complex terrain are improved, but motion noise is introduced that reduces detection accuracy
Solution Approach 1:
The reference coil serves as an intermediary that captures motion noise introduced during aerial movement, providing a reference signal that enables post-processing suppression of this noise from the measuring coil data.
Solution Approach 2:
The motion noise, which is harmful to measurement accuracy, is converted into a useful reference signal by the reference coil. This reference signal is then used to suppress the same-frequency noise in the measuring coil, turning the harmful motion noise into a benefit for noise suppression.
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 simplifies the survey system, improves signal-to-noise ratio, and enables one-time cancellation of motion noise, enhancing detection depth and accuracy by decoupling additive motion noise from real magnetic field signals.
Implementation Method 1
the coil cuts the magnetic induction line of the geomagnetic field when moving in air, and the motion drift consistent with the motion frequency of the coil is introduced into the coil
Data Source
AI summary
A semi-airborne electromagnetic survey device and a semi-airborne electromagnetic survey method based on coaxial coplanar mutual reference coil assembly are provided. The device includes a measuring coil and a reference coil with linear correlation of additive motion noise; the reference coil and the measuring coil have a same bandwidth, are coaxial and coplanar and are in hard connection or soft connection; detection resolution of the reference coil only distinguishes the additive motion noise; detection resolution of the measuring coil distinguishes real vertical magnetic field signals and motion noise simultaneously; the reference coil has a much smaller outer diameter than the measuring coil. In the method, one coil only receives the additive motion noise, and an other coil simultaneously receives the additive motion noise and the real vertical magnetic field signals; and the additive motion noise received by the two coils is cancelled to obtain the real vertical magnetic field signals.