Radar Heart Rate Extraction Using Multi-Method Signal Quality Scoring
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Solution Overview
Problem
Existing non-contact radar systems for measuring physiological parameters, such as heart rate, face challenges in removing unrelated artifacts from motion signals, leading to inaccurate or absent heart rate readings due to instrument noise, muscle spasms, and external motion artifacts.
Innovation Solution
A frequency-modulated radar system processes in-phase and quadrature signals using multiple methods to filter out unwanted frequencies, assign quality scores to heart rate segments, and select the most accurate output to derive heart rate, employing algorithms to optimize accuracy and validate continuous readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a radar system is used to detect physiological parameters non-contactly, then the convenience and non-invasive nature of measurement is improved, but the accuracy of detection deteriorates due to noise artifacts from instrument noise, muscle spasms, external motion, and signal bias drift
Solution Approach 1:
The patent segments the detection process into multiple independent processing methods (phase calculation, complex signal processing, linear combination) that are evaluated separately. Each method processes the radar signal independently and is assigned a quality score, allowing the system to select the most reliable method for each specific measurement condition rather than using a single fixed approach.
Solution Approach 2:
The patent dynamically changes processing parameters by selecting different signal processing methods based on quality scores. The system adjusts which processing algorithm is applied in real-time based on the characteristics of the received signal, optimizing the balance between noise rejection and physiological signal detection for each measurement instance.
2Reliability
If multiple signal processing methods are used to improve heart rate detection accuracy, then the reliability of measurement is improved, but the device complexity increases
Solution Approach 1:
The patent implements a dynamic selection mechanism where the system automatically chooses the most appropriate signal processing method based on real-time quality assessment. The processor evaluates multiple processing approaches and selects the one with the highest quality score for each time segment, making the system adaptable to varying signal conditions without requiring manual configuration.
Solution Approach 2:
The system performs self-assessment of signal quality and automatically selects the optimal processing method without external intervention. The quality scoring mechanism enables the radar system to autonomously determine which processing approach yields the most reliable heart rate measurement, reducing the need for complex manual tuning or external calibration procedures.
3Measurement precision
If quality scores are assigned to validate and select processing outputs, then the accuracy of heart rate derivation is improved, but the processing time and computational load increase
Solution Approach 1:
The patent applies partial processing by evaluating multiple signal processing methods simultaneously and selectively applying quality scoring only to the most promising candidates. The system computes quality scores for different processing outputs and selects the best one, rather than exhaustively processing all possible methods with equal depth, thus reducing overall computational burden while maintaining accuracy.
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
The system effectively filters out noise and artifacts, providing accurate and reliable heart rate measurements by selecting the highest quality method and frequency range, enhancing the precision of derived heart rates and enabling real-time monitoring.
Implementation Method 1
a radar system can be used to detect motion of the subject without contacting the subject
Implementation Method 2
a receiver of the radar detects a reflection of the signal, a portion of which is reflected from the subject's body
Implementation Method 3
the radar is a frequency-modulated radar, for example, a frequency-modulated continuous-wave radar
Data Source
AI summary
Apparatus and methods are described including deriving a subject's heart rate from in-phase and the quadrature signals received by a radar. The in-phase and quadrature signals are processed to generate two or more outputs using two or more respective methods. For each of the two or more outputs, for each of a plurality of time segments, the subject's heart rate is derived from the filtered signal, and quality scores are assigned to the subject's heart rate as derived for each of the plurality of time segments from each of the two or more outputs. At least partially based upon the quality scores, the subject's heart rate is derived using the output of one of the methods. Other applications are also described.