Range-Gated RF Physiology Sensing With Pulsed Oscillation Circuit
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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 non-compliance with global RF regulatory requirements, while also being prone to RF interference and lacking effective range gating for precise physiology characteristic detection.
Innovation Solution
A RF sensor circuit with a dielectric resonator oscillator and a switched circuit that generates pulsed RF signals, providing improved frequency stability and fast switching characteristics, coupled with a processor for processing reflected pulses to derive physiological indicators like respiration and heart rate, and designed to comply with RF regulatory requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If continuous wave RF signals are used for motion sensing, then the sensor can detect both near and far objects, but false triggers occur due to motion artifact interference and high sensitivity at close range
Solution Approach 1:
The patent applies periodic pulsed RF signals instead of continuous wave signals. The pulse repetition frequency and pulse width are controlled to create periodic transmission intervals, enabling range gating that excludes close-range false triggers while maintaining far-range detection capability. The periodic nature allows time-based separation of transmitted and received signals for different distance ranges.
Solution Approach 2:
The patent implements preliminary range gating by setting a minimum detection range through pulse timing control. The system pre-configures the detection window to start after a specific time delay following each transmitted pulse, effectively excluding close-range objects from detection before the measurement process begins.
2Measurement precision
If narrow sensing region is used for precise range gating, then medium range detection is improved, but the sensor cannot detect objects at all ranges and may be prone to RF interference
Solution Approach 1:
The patent employs dynamic adjustment of pulse width and pulse repetition frequency to adapt the sensing region characteristics. By varying these parameters, the system can optimize the range gate width for different application scenarios, transitioning between narrow precision gating and wider coverage as needed, rather than being fixed to a single sensing region configuration.
Solution Approach 2:
The system changes key RF parameters including pulse width, pulse repetition frequency, and center frequency to achieve different detection configurations. These parameter adjustments enable the sensor to switch between narrow precise range gating for medium ranges and wider gating for broader detection coverage, while maintaining compliance with RF regulatory requirements.
3Speed
If fast switching is used for pulse generation, then range gating response time is improved, but frequency stability deteriorates
Solution Approach 1:
The patent separates the frequency generation and pulse switching functions into distinct components. A stable voltage-controlled oscillator (VCO) generates the continuous RF carrier signal with high frequency stability, while a separate pulse generator and switch control the temporal characteristics. This segmentation allows fast switching without disrupting the frequency stability of the oscillator core.
Solution Approach 2:
The patent introduces a switch as an intermediary element between the stable VCO and the antenna. The switch rapidly gates the already-stabilized RF signal without requiring the VCO itself to switch, thereby achieving fast pulse generation while preserving the frequency stability established by the high-Q VCO circuitry.
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 enables accurate and reliable detection of physiological characteristics with improved range gating, reduced false triggers, and compliance with RF regulatory standards, enhancing the sensor's performance and effectiveness in physiology sensing applications.
Implementation Method 1
a dielectric resonator oscillator configured to generate a stable radio frequency oscillating signal
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
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 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.