Non-contact Vibration Measurement via Nonlinear Phase Modulation
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Solution Overview
Problem
Existing microwave and millimeter-wave technologies can only detect the frequency of mechanical vibration, not the amplitude, and require calibration of signal amplitude for accurate measurement.
Innovation Solution
A method and system based on nonlinear phase modulation that measures frequency and amplitude of periodic displacement without signal amplitude calibration, utilizing harmonic ratios derived from Bessel functions to determine movement amplitude, and incorporates self-verification for accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear approximation is used in Doppler radar to detect frequency of movement, then the system can detect frequency, but it cannot measure amplitude of movement
Solution Approach 1:
The patent transitions from linear approximation to nonlinear phase modulation analysis by examining higher-order harmonics. By analyzing the ratios of harmonic components (H2/H1, H3/H1, etc.) in the phase-modulated signal, the system can determine both frequency and amplitude of movement without requiring separate measurement mechanisms.
Solution Approach 2:
The patent moves from analyzing only the fundamental frequency component to analyzing the spectral dimension by examining multiple harmonic orders. This dimensional expansion in frequency domain analysis enables simultaneous extraction of both amplitude and frequency information from the phase modulation signal.
2Measurement precision
If signal amplitude calibration is performed for accurate measurement, then measurement accuracy improves, but system complexity and calibration requirements increase
Solution Approach 1:
The system performs self-calibration by using the harmonic ratio relationships inherent in the phase modulation signal. The amplitude information is extracted from the relative strengths of different harmonic components, which naturally contain the calibration information needed, eliminating the requirement for external calibration procedures.
Solution Approach 2:
The patent employs a feedback mechanism where the measured harmonic ratios are compared against theoretical relationships to verify measurement accuracy. This self-verification process ensures that the amplitude and frequency measurements are correct without requiring external calibration references.
3Measurement precision
If nonlinear phase modulation analysis is used to measure both frequency and amplitude, then measurement capability is enhanced, but signal processing complexity increases
Solution Approach 1:
The patent segments the phase modulation signal into distinct harmonic components (H1, H2, H3, etc.) and analyzes each component separately. By computing the ratios between these segmented harmonic components, the system extracts amplitude and frequency information in a systematic and computationally efficient manner.
4Reliability
If wide angle incidence is considered in practical applications, then measurement robustness improves, but analysis complexity increases
Solution Approach 1:
The patent accounts for wide angle incidence effects by analyzing how the harmonic ratio parameters change with incident angle. By incorporating angle-dependent corrections into the harmonic ratio analysis, the system maintains measurement accuracy across a range of incidence angles without requiring complex real-time geometric calculations.
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
Enables accurate non-contact measurement of both frequency and amplitude of mechanical vibrations over a wide range with high precision and simple radio architecture, without the need for signal amplitude calibration, and maintains accuracy even with wide angle incidence.
Implementation Method 1
The mechanism of most of the microwave displacement-related measurement systems is the detection of the phase shift caused by the movement of the target
Implementation Method 2
a mechanical vibration detection method and system based on the measurement of the nonlinear effect inherent in a phase modulation mechanism
Data Source
AI summary
A non-contact detection technique of measuring both the frequency and the amplitude of periodic movement using a property of nonlinear phase modulation is provided. In one embodiment, the technique can utilize a 22-40 GHz radar sensor. Embodiments do not require calibration of signal amplitude for accurate measurement of movement amplitude. In addition, self-verification is possible. Furthermore, embodiments can provide measurements of frequency and amplitude using a very simple architecture. The method can be used to detect movements with amplitudes larger than 0.335 of the carrier wavelength for a fixed carrier frequency system and 0.214 of the minimum carrier wavelength for a frequency tunable system.