Radar Breathing Signal Detection Using Clutter Suppression

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Solution Overview

Problem

Existing radar systems have limited capability in non-contact detection of human breathing signals, especially in line-of-sight (LOS) or non-line-of-sight (NLOS) environments, and fail to accurately identify human targets and discriminate between multiple targets, due to noise and clutter interference.

Innovation Solution

The method involves clutter suppression using Singular Value Decomposition (SVD) and skewness analysis, combined with time-domain processing and harmonic ratio analysis, to extract breathing signals and estimate human breathing rates, posture, and detect stop-breathing events, employing ultra-wide band (UWB) or pseudo-noise continuous wave (PN-UWB) radar technologies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If non-contact radar monitoring is used to detect human breathing signals, then vital sign monitoring capability is improved, but detection accuracy deteriorates due to noise and clutter interference

Engineering Contradiction:

Improvenon-contact monitoring capabilityVSAvoidbreathing signal detection accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent extracts the breathing signal component from the complex radar return signal by isolating the specific frequency band corresponding to respiratory movements. This is achieved through bandpass filtering and signal processing techniques that separate the useful breathing information from the harmful noise and clutter, thereby improving detection accuracy while maintaining non-contact operation

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces an intermediary signal processing system that includes clutter suppression algorithms and harmonic ratio analysis. These intermediary processing stages act as mediators between the raw radar signal and the final breathing rate measurement, filtering out interference and enhancing the accuracy of vital sign detection

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If radar systems are used to detect targets behind walls or obstacles, then security monitoring capability is improved, but target identification accuracy deteriorates due to signal attenuation and distortion

Engineering Contradiction:

Improvedetection capability in NLOS environmentsVSAvoidtarget identification accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent applies preliminary clutter suppression using Singular Value Decomposition (SVD) before target detection. This preliminary action removes the majority of static and dynamic clutter signals, creating a cleaner signal basis for subsequent target identification. By preparing the signal in advance, the system can accurately identify targets even when they are behind obstacles

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the signal processing parameters by analyzing the harmonic ratios of the breathing signal. By examining the frequency spectrum and calculating ratios between harmonic components, the system can distinguish human targets from other objects even when the signal has been attenuated or distorted by walls and obstacles

Inventive Principle:

Principle #35Parameter changes

3Area of stationary object

If multiple targets are detected in the same monitoring area, then monitoring coverage is improved, but discrimination accuracy deteriorates due to signal overlap and interference

Engineering Contradiction:

Improvemonitoring coverage areaVSAvoidtarget discrimination accuracy

Core Design Contradiction:

Area of stationary objectVSMeasurement precision

Solution Approach 1:

The patent segments the monitoring area into multiple range bins based on the radial velocity and distance information from the radar signal. By dividing the detection space into distinct bins, the system can process and analyze signals from different targets separately, improving discrimination accuracy while maintaining comprehensive coverage of the monitoring area

Inventive Principle:

Principle #1Segmentation

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 accurate detection of human breathing rates, posture estimation, and discrimination between human and animal targets, reducing false alarms and improving detection accuracy in noisy environments, even behind obstacles like walls.

Implementation Method 1

a method for detecting a target using a radar

Methodology Applied

Scientific EffectRadar: Radar

Implementation Method 2

receiving radar data from the radar

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

Physiological sensing based on Doppler radar is gaining popularity

Methodology Applied

Scientific EffectDoppler Effect: Doppler Effect

Data Source

PatentUS10401479B2Remote sensing of human breathing at a distance

Publication Date: 2019.09.03 UNIVERSITY OF OTTAWA

AI summary

A method and system is described for using radar to provide non-contact detection of human breathing at a distance. Radar data is processed to remove clutter and enable detection of a breathing signal. The breathing signal can be used to determine breathing rate or posture of the target. Static obstructions can be removed from the radar data to identify target breathing signal. The system and method can be applicable to emergency response, home or institutional monitoring applications and for detection of medical conditions.