Magnetometer Interference Reduction via Time-Varying Frequency
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Solution Overview
Problem
Conventional magnetometer systems are susceptible to electromagnetic interference from environmental sources, leading to inaccurate measurements of respiratory characteristics due to their reliance on fixed-frequency electromagnetic sources, which are ineffective in high-noise environments and cannot adequately reduce interference in received magnetic fields.
Innovation Solution
The system employs magnetometers that generate a magnetic field with a frequency randomly or pseudo-randomly varied over time, minimizing interference by using a time-varying magnetic field characteristic, and employing spread spectrum techniques to extract the desired signal from periodic noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fixed-frequency electromagnetic sources are used in magnetometer systems, then the system structure is simple and easy to implement, but the system is susceptible to electromagnetic interference from environmental sources leading to inaccurate measurements
Solution Approach 1:
The patent applies dynamics by transitioning from fixed-frequency electromagnetic sources to time-varying frequency sources. The magnetometer system modulates the frequency of its electromagnetic field over time, allowing it to avoid stationary interference frequencies and continuously adapt to changing environmental conditions, thereby improving measurement reliability without requiring complex additional hardware
Solution Approach 2:
The patent changes the frequency parameter of the electromagnetic source from a constant value to a time-varying value. By continuously varying the frequency parameter, the system avoids resonance with environmental interference sources and improves signal detection accuracy in noisy environments
2Reliability
If conventional filtering systems with multiple filters are employed to reduce electromagnetic interference, then measurement accuracy improves, but device complexity and loss of information increase
Solution Approach 1:
The patent applies preliminary action by varying the frequency of the electromagnetic source before interference can occur. By proactively changing the frequency parameter over time, the system prevents interference from coupling into the measurement band, eliminating the need for reactive filtering that would otherwise be required to remove interference after it contaminates the signal
3Object-affected harmful factors
If conventional filtering systems with multiple filters are used to limit interference, then electromagnetic interference reduction improves, but device complexity increases
Solution Approach 1:
The patent extracts the interference problem from the solution by removing the need for complex filtering systems. Instead of adding multiple filters to remove interference, the system extracts the interfering frequencies from the measurement band by varying its operating frequency, achieving interference reduction through source modulation rather than signal filtering
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 significantly reduces electromagnetic interference, enhances the accuracy of measured changes in magnetic fields, and allows for the detection of small magnetic fields in high-noise environments, leading to precise determination of anatomical and physiological characteristics.
Implementation Method 1
one magnetometer is adapted to transmit a specific high frequency AC magnetic field
Implementation Method 2
the paired magnetometers are responsive to changes in a spaced distance therebetween; the changes being reflected in changes in the strength of the magnetic field
Data Source
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Figure 5
AI summary
Magnetometer systems, and associated methods, are provided including a first magnetometer (22a,24a) adapted to generate an external magnetic field having a characteristic that is varied over time, and a second magnetometer (22b,24b) adapted to receive the magnetic field and generate at least one magnetometer signal representing a change in the magnetic field. In one embodiment, the magnetic field characteristic includes the frequency of the generated magnetic field. In another embodiment, the magnetic field characteristic includes the frequency period of the magnetic field.