FCFMSIL Radar Multi-Subject Vital Sign Detection
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Solution Overview
Problem
Conventional self-injection-locked (SIL) radar can only detect vital signs of a single subject due to its limited sensitivity, while frequency-modulated continuous wave (FMCW) radar has insufficient range resolution for distinguishing multiple objects at similar ranges, making it difficult to detect vital signs of multiple subjects effectively.
Innovation Solution
The integration of a frequency-converted frequency-modulated self-injection-locked (FCFMSIL) radar system, which includes a self-injection-locked oscillator, frequency conversion unit, antenna, demodulation unit, and processing unit, allows for improved range resolution and multi-object detection by converting and injecting signals to determine the frequency and phase of tones corresponding to one or multiple objects, enabling the use of a super resolution algorithm to enhance processing efficiency and accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional SIL radar is used to detect vital signs, then sensitivity to tiny vibration is improved, but the ability to detect multiple subjects is worsened
Solution Approach 1:
The patent merges the SIL radar architecture with FMCW modulation technique. The voltage-controlled oscillator is injected with reflected signals to achieve self-injection-locking while using frequency-modulated continuous wave transmission. This combination enables the system to maintain high sensitivity to tiny vibrations through self-injection-locking while acquiring range information through FMCW, allowing detection of multiple subjects at different distances
Solution Approach 2:
The radar system achieves multi-functionality by integrating both SIL and FMCW capabilities in a single architecture. The same transmitter and receiver hardware perform both vital sign detection (through self-injection-locking sensitivity) and range measurement (through FMCW time-delay estimation), enabling the system to detect multiple subjects with different ranges and vital signs simultaneously
2Adaptability or versatility
If conventional FMCW radar is used to detect multiple objects, then multi-object detection capability is improved, but range resolution is worsened
Solution Approach 1:
The patent employs feedback through self-injection-locking where the reflected signal from targets is injected back into the voltage-controlled oscillator. This feedback mechanism creates a locked state that enhances the system's ability to resolve closely spaced targets by improving the signal-to-noise ratio and enabling more precise frequency and phase measurements, thereby improving range resolution for multi-object detection
3Measurement precision
If bandwidth is increased in FMCW radar to improve range resolution, then range resolution is improved, but hardware complexity and cost are worsened
Solution Approach 1:
The patent changes the operating parameters of the radar system by using self-injection-locking to enhance frequency and phase measurement precision. Instead of relying solely on increased bandwidth for range resolution, the system achieves improved resolution through parameter optimization in the signal processing domain, including precise estimation of time-delay, frequency, and phase of reflected signals, thereby avoiding the need for complex high-bandwidth hardware
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 the FCFMSIL radar to accurately detect vital signs of multiple subjects by improving range resolution and operational efficiency, allowing for precise identification of objects based on the relation of frequency and phase, and applying a super resolution algorithm to process tones corresponding to multiple objects, thereby enhancing detection capabilities.
Implementation Method 1
a voltage-controlled oscillator in the SIL radar is injected with and locked by a reflected signal from the subject to enter a self-injection-locked state
Implementation Method 2
The frequency conversion unit is coupled to the SILO to receive and convert the oscillation signal into a frequency-modulated continuous wave signal
Implementation Method 3
The demodulation unit is coupled to the SILO to receive and demodulate the oscillation signal into an in-phase demodulated signal and a quadrature demodulated signal
Data Source
AI summary
A FCFMSIL radar includes a SILO, a frequency conversion unit, an antenna unit, a demodulation unit and a processing unit. The frequency conversion unit converts an oscillation signal of the SILO into a FMCW signal. The antenna unit transmits the FMCW signal to an area as a transmitted signal and receives a reflected signal from the area as a received signal. The frequency conversion unit converts the received signal into an injection signal and injects it into the SILO. The demodulation unit demodulates the oscillation signal into an in-phase demodulated signal and a quadrature demodulated signal. The processing unit processes the in-phase and the quadrature demodulated signals to obtain a baseband signal and thus acquire a phase and a frequency of a tone in the frequency-domain baseband signal, and determines the tone corresponding to one or multiple objects based on the phase and frequency of the tone.