Range-Gated RF Physiology Sensor Circuit for False Trigger Reduction
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Solution Overview
Problem
Existing radio frequency (RF) motion sensors face challenges such as false triggers due to high sensitivity at close ranges, difficulty in sensing objects at medium ranges, and lack of global RF regulatory acceptance, which affects their effectiveness in detecting physiological characteristics like breathing and heart rate.
Innovation Solution
A radio frequency motion sensor circuit with a dielectric resonator oscillator and a switched wideband oscillator or amplifier, which provides stable frequency oscillations and fast switching capabilities for range gating, ensuring accurate and regulated RF signal transmission and reception.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If continuous wave Doppler radar is used for motion sensing, then the sensor can detect both near and far objects, but it produces false triggers due to high sensitivity at close range and cannot provide range gating
Solution Approach 1:
The patent employs pulse Doppler radar that transmits periodic RF pulses instead of continuous waves. By transmitting short pulses at controlled intervals and using range gating to process only echoes returning within specific time windows, the system achieves reliable motion detection while eliminating false triggers from close-range objects and clutter.
2Measurement precision
If pulse Doppler radar with narrow sensing region is used, then range gating is achieved, but the sensor has difficulty sensing objects at medium ranges and may be prone to RF interference
Solution Approach 1:
The patent implements adjustable range gating parameters that can be dynamically configured to optimize detection for different scenarios. The system can adapt the pulse width, pulse repetition frequency, and gate timing to balance between range resolution and detection reliability across various distances, allowing reliable sensing at medium ranges while maintaining precision.
3Measurement precision
If impulse radar or ultra-wideband radar is used for range gating, then narrow sensing region is achieved, but the sensor lacks global RF regulatory acceptance as an intentional radiator
Solution Approach 1:
The patent uses conventional RF frequencies (e.g., 2.4 GHz ISM band) that have global regulatory acceptance, rather than ultra-wideband frequencies. By adjusting RF parameters such as pulse width, power level, and modulation scheme, the system achieves adequate range resolution and sensing precision while ensuring compliance with international RF regulations for intentional radiators.
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 solution enhances RF oscillator frequency stability while maintaining fast switching characteristics, reducing false triggers and improving the sensor's ability to detect physiological characteristics within defined ranges, ensuring compliance with RF regulatory requirements.
Implementation Method 1
a dielectric resonator oscillator and a switched wideband oscillator or amplifier, which provides stable frequency oscillations
Implementation Method 2
Continuous wave (CW) Doppler radar motion sensors emit a continuous wave radio frequency (RF) carrier and mix the transmitted RF with the return echoes to produce a difference frequency equal to the Doppler shift produced by a moving target
Data Source
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AI summary
A sensor for physiology sensing may be configured to generate oscillation signals for emitting radio frequency pulses for range gated sensing. The sensor 402 may include a radio frequency transmitter configured to emit the pulses and a receiver configured to receive reflected ones of the emitted radio frequency pulses. The received pulses may be processed to detect physiology characteristics such as motion, sleep, respiration and/or heartbeat. In some embodiments, the sensor may employ a circuit including a pulse generator configured to generate signal pulses. The circuit may also include a dielectric resonator oscillator configured to generate a radio frequency oscillating signal. A switched oscillation circuit may be coupled to the pulse generator and the dielectric resonator oscillator. The switched circuit may be configured to generate a pulsed radio frequency oscillating signal for emitting the radio frequency pulses.