Radar Signal Processing for Non-Contact Vital Sign Acquisition
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Solution Overview
Problem
Existing non-contact vital sign sensing technologies face challenges in accurately estimating heart rate due to overwhelming respiration movements, particularly when using radar signals, as higher order harmonics of respiration can distort heartbeat components, leading to errors and inaccuracy.
Innovation Solution
A method and apparatus utilizing peak detection and polynomial fitting to filter out respiration signals from radar baseband signals, allowing for real-time extraction of heartbeat pulses and estimation of heart and respiration rates, which reduces spectral distortion and harmonic interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If spectral-domain analysis methods are used to estimate heart rate from radar signals, then heart rate can be extracted, but respiration harmonics cause spectral distortion that overwhelms heartbeat signals and reduces measurement precision
Solution Approach 1:
The patent extracts and removes the respiration signal component from the radar baseband signal before estimating heart rate. By separating the respiration movement estimation from the heartbeat signal analysis, the harmful spectral distortion caused by respiration harmonics is eliminated, allowing accurate heart rate measurement without information loss.
Solution Approach 2:
The patent segments the vital sign estimation process into distinct steps: first estimating respiration movement, then subtracting it from the original signal, and finally extracting heartbeat pulses from the residual signal. This segmentation allows each component to be processed separately, preventing spectral distortion from affecting the heartbeat measurement.
2Measurement precision
If traditional spectral analysis methods are used for vital sign estimation, then heart rate can be obtained, but the processing delay exceeds 20 seconds which reduces productivity
Solution Approach 1:
The patent replaces traditional frequency-domain spectral analysis with time-domain signal processing methods. By using time-domain subtraction of estimated respiration signals and peak detection algorithms, the system achieves fast vital sign extraction with processing delays reduced to seconds, dramatically improving productivity while maintaining measurement precision.
3Reliability
If respiration signals are not suppressed, then the complete radar baseband signal is analyzed, but higher order harmonics of respiration distort the heartbeat components leading to errors
Solution Approach 1:
The patent converts the harmful respiration signal into a useful component by first estimating it separately and then systematically removing it from the composite signal. This approach transforms the source of spectral distortion into a known quantity that can be subtracted, eliminating the harmful harmonics and improving estimation reliability.
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 enables fast and accurate vital sign estimation with reduced delay, providing heart rate readings within seconds and real-time changes in heart and respiration rates, improving upon traditional spectral-domain methods by suppressing respiration signals and extracting heartbeat pulses in the time domain.
Implementation Method 1
a radar signal is transmitted toward a target and a signal representative of the receive signal is analyzed to identify at least two adjacent peaks of a first vibration
Implementation Method 2
phase information of the radar signal is used to generate a waveform
Data Source
AI summary
Various examples are provided for non-contact vital sign acquisition. Information can be provided regarding vibrations of a target using a radar signal such as, e.g., non-contact vital sign measurement. Examples include estimation of heart rate, change in heart rate, respiration rate, and/or change in respiration rate, for a human or other animal. Implementations can produce one or both rates of vibration and/or change in one or both rates of vibration for a target other than an animal or human experiencing two vibrations at the same time, such as a motor, a vehicle incorporating a motor, or another physical object. Some implementations can estimate the respiration movement in the radar baseband output signal. The estimated respiration signal can then be subtracted from radar signals in the time domain and, optionally, can be further enhanced using digital signal processing techniques, to produce an estimate of the heartbeat pulses.