Range-Gated RF Physiology Sensor With Stable Pulsed Oscillation
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Solution Overview
Problem
Existing radio frequency sensors for physiological characteristic detection face issues such as false triggers due to high sensitivity at close range, difficulty in medium range sensing, RF interference, and non-compliance with regulatory requirements, while existing range-gated systems have stability and switching speed limitations.
Innovation Solution
A radio frequency sensor with a dielectric resonator oscillator coupled to a switched wideband oscillator or amplifier, using injection locking for frequency stability and fast switching, and a pulse generator to produce pulsed RF signals for range-gated physiology sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a continuous wave (CW) Doppler radar sensor is used, then motion sensing capability is provided, but false triggers occur due to high sensitivity at close range and inability to limit detection range
Solution Approach 1:
The patent applies periodic pulsed action instead of continuous wave transmission. The radar sensor transmits periodic pulses with controlled width and repetition frequency, enabling range gating by transmitting only during specific time windows. This periodic pulsed transmission eliminates false triggers from unwanted ranges while maintaining motion detection capability in the desired range zone.
2Object-affected harmful factors
If pulse Doppler radar is used with range gating, then false triggers are reduced, but frequency stability and switching speed limitations occur
Solution Approach 1:
The patent uses a dielectric resonator oscillator that is preliminarily tuned and stabilized before pulse transmission begins. The oscillator frequency is pre-stabilized using the dielectric resonator's high Q-factor properties, ensuring frequency stability is established before the rapid switching required for pulsed operation. This preliminary frequency stabilization prevents frequency drift during the pulsing operation.
3Manufacturing precision
If narrow pulse width is used for range gating, then range resolution is improved, but sensing capability at medium ranges deteriorates
Solution Approach 1:
The patent employs dynamic adjustment of pulse width and pulse repetition frequency based on the desired detection range. For medium range detection, the system dynamically increases pulse width to enhance energy transmission and reception, while for precise range gating, it reduces pulse width. This dynamic adaptation allows the sensor to optimize between range resolution and medium range sensing capability depending on operational requirements.
4Measurement precision
If high power RF transmission is used, then detection sensitivity is improved, but compliance with RF regulatory requirements becomes difficult
Solution Approach 1:
The patent uses periodic pulsed transmission with controlled duty cycle to reduce average RF power emission while maintaining peak power for sufficient detection sensitivity. By transmitting high power only during brief pulse intervals rather than continuously, the system achieves the required detection sensitivity for physiological monitoring while keeping average power emissions within regulatory limits 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 sensor achieves stable RF frequency output with fast switching, enabling accurate range-gated detection of physiological characteristics like breathing and heart rate, compliant with regulatory standards and resistant to interference.
Implementation Method 1
a dielectric resonator oscillator coupled to a switched wideband oscillator or amplifier, using injection locking for frequency stability
Implementation Method 2
a switched circuit configured to amplify the radio frequency oscillating signal in synchronism with the pulse signal
Data Source
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AI summary
The present invention relates to a radio frequency motion sensor comprising a radio frequency transmitter configured to emit radio frequency pulses, and a switched receiver configured to receive reflected ones of the emitted radio frequency pulses. The radio frequency transmitter comprises a pulse generator configured to generate signal pulses, a dielectric resonator oscillator configured to generate a stable radio frequency oscillating signal, and a switched circuit coupled to the pulse generator and the dielectric resonator oscillator. The switched circuit is configured to generate a pulsed radio frequency oscillating signal that is modulated by the signal pulses of the pulse generator and whose dominant frequency is derived from the dielectric resonator oscillator. Furthermore, the switched receiver is switched in accordance with a timing signal from the pulse generator.