Microwave Motion Sensor Using Self-Injection Locking for Cardiopulmonary Detection
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Solution Overview
Problem
Conventional motion/vibration sensors, particularly those using infrared technology, are affected by environmental temperature and often fail to function properly, and microwave sensors face challenges in accurately detecting bio-physiology signals like breath and heartbeat frequencies due to noise and complexity issues.
Innovation Solution
A motion/vibration sensor system incorporating a transmit/receive antenna unit, an oscillation unit, and a frequency-mixing unit that uses radio frequency waves and self-injection locking to detect and demodulate bio-physiology signals, allowing for non-contact detection of cardiopulmonary signals by modulating and demodulating reflected waves to produce a baseband output signal representing motion/vibration information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If infrared technology is used for motion/vibration sensing, then the sensor can detect motion and vibration, but it is affected by environmental temperature and may not function properly
Solution Approach 1:
The patent replaces the infrared sensing mechanism with a microwave-based electromagnetic sensing system. The microwave motion sensor transmits microwave signals that reflect off moving targets, and the frequency shift is detected through Doppler effect, eliminating the temperature sensitivity inherent in infrared technology while maintaining motion detection capability
Solution Approach 2:
The patent changes the operating frequency parameter from infrared range to microwave range. By operating at microwave frequencies (e.g., 2.4 GHz), the sensor exploits the Doppler frequency shift characteristic of microwave waves interacting with moving objects, providing temperature-independent motion detection through frequency-based measurement rather than temperature-sensitive infrared detection
2Measurement precision
If microwave motion sensor is used to detect bio-physiology signals, then the sensor can detect frequency shift indicating moving targets, but it faces noise and complexity issues in accurately detecting breath and heartbeat frequencies
Solution Approach 1:
The patent segments the signal processing function by separating the oscillation unit that generates the microwave signal from the frequency-mixing unit that processes the reflected signal. The oscillation unit operates at a stable frequency while the frequency-mixing unit detects frequency shifts, allowing independent optimization of signal generation and detection functions to improve measurement precision while managing system complexity
Solution Approach 2:
The patent introduces a frequency-mixing unit as an intermediary between the transmit/receive antenna and the signal processing circuitry. This intermediary component mixes the reflected microwave signal with the original oscillation signal to produce beat frequencies that correspond to the motion frequency, simplifying the detection of bio-physiology signals like breath and heartbeat frequencies by converting them to audible or easily processable frequency ranges
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 solution enables accurate and reliable detection of cardiopulmonary signals, such as breath and heartbeat frequencies, with improved sensitivity and reduced noise interference across various operation frequencies, enhancing the effectiveness of bio-physiology signal monitoring.
Implementation Method 1
The oscillation unit receives the reflected detection signal from the transmit/receive antenna unit for self-injection locking
Implementation Method 2
The frequency-mixing unit mixes and demodulates the reflected detection signal from the transmit/receive antenna unit with the output signal from the oscillation unit into a baseband output signal
Implementation Method 3
The transmit/receive antenna unit receives an output signal from the oscillation unit and transmits a detection signal toward at least one object. The detection signal is reflected by the object as a reflected detection signal and received by the transmit/receive antenna unit
Data Source
AI summary
A motion/vibration sensor includes a transmit/receive antenna unit, an oscillation unit and a frequency-mixing unit. The transmit/receive antenna unit receives an output signal from the oscillation unit and transmits a detection signal toward at least one object. The detection signal is reflected by the object as a reflected detection signal and received by the transmit/receive antenna unit. The oscillation unit receives the reflected detection signal from the transmit/receive antenna unit for self-injection locking; and the frequency-mixing unit receives the reflected detection signal from the transmit/receive antenna unit for frequency demodulation. The frequency-mixing unit mixes and demodulates the reflected detection signal from the transmit/receive antenna unit with the output signal from the oscillation unit into a baseband output signal which represents a motion/vibration information.