Radar Biometric Signal Noise Removal via FFT Filtering
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Solution Overview
Problem
Existing methods for measuring biometric signals using microwave radar face challenges in effectively removing random noises that are mixed with biometric signals, leading to reduced accuracy in signal measurement.
Innovation Solution
A method and apparatus that utilize a microwave Doppler radar system with a single transmission antenna and multiple reception antennas to generate and process Doppler IF signals, employing Fast Fourier Transform and digital filtering to distinguish and remove random noises from biometric signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional microwave radar is used to measure biometric signals, then the radar can detect Doppler effects from body movements, but random noises from external factors and body movements are mixed with the biometric signals, reducing measurement accuracy
Solution Approach 1:
The patent segments the received radar signal into multiple frequency components using Fast Fourier Transform (FFT). By dividing the signal spectrum into different frequency bins, the system can identify and separate periodic biometric signals (heartbeat, respiration) from aperiodic random noises, thereby improving measurement accuracy while eliminating noise interference
Solution Approach 2:
The patent extracts periodic signal components from the mixed signal by analyzing the frequency domain characteristics. Using spectral analysis and peak detection algorithms, the system extracts the periodic biometric signals at specific frequencies while leaving the aperiodic random noises in the residual signal, thus removing the harmful noise components
2Measurement precision
If signal processing methods are applied to remove random noises, then measurement accuracy improves, but the complexity of the radar system increases
Solution Approach 1:
The patent replaces complex hardware-based noise filtering mechanisms with software-based digital signal processing algorithms. By using FFT and spectral analysis in the digital domain, the system achieves effective noise removal without adding complex physical filtering components, thus improving accuracy while maintaining relatively simple device structure
Solution Approach 2:
The patent changes the analysis domain from time domain to frequency domain by applying Fast Fourier Transform. This parameter transformation allows periodic biometric signals to be distinguished from aperiodic noises based on their frequency characteristics, simplifying the noise removal process while improving measurement precision
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 proposed solution significantly improves the accuracy of biometric signal measurement by effectively reducing and removing random noises, thereby enhancing the reliability of contactless biometric signal measurement using microwave radar.
Implementation Method 1
generating, by a voltage-controlled oscillator (VCO) of an IF signal generator, an oscillation frequency of a predetermined period using a voltage V(t) applied from the outside
Implementation Method 2
Doppler radar uses the Doppler effect of radio waves to detect a moving target on the basis of the difference between the frequency of radar waves transmitted toward a target object and the frequency of reflected radio waves
Implementation Method 3
converting, by an analog/digital converter, each of multiple Doppler IF signals input from the IF signal generator into digital data; configuring digital signals collected by the analog/digital converter during a unit time into a data set having symbols at sampling time intervals by a Fast Fourier Transformer, and converting the data set into a frequency component symbol set having multiple indices
Data Source
AI summary
The present invention relates to a method of effectively removing various vibration noises using microwave Doppler radar, and an apparatus therefor. The method comprises the steps of: (a) generating and transmitting an oscillation frequency to a dynamic target, and receiving a signal reflected from the dynamic target and various signals generated around the dynamic target; (b) generating a Doppler IF signal from each of n received signals; (c) converting each Doppler IF signal into digital data; (d) configuring digital signals into a data set, and converting the data set into a frequency component symbol set; (e) calculating a value by adding index symbols and dividing by n reception antennas; and (f) classifying deviation between spectrum components of a commonly-generated periodic signal and an uncommon aperiodic signal, and obtaining only a periodic signal through filtering. The present invention can improve accuracy of sensing a biometric signal.