Subsampling Motion Detection Using Injection-Locked RF Oscillators
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Solution Overview
Problem
Existing motion detectors using phase lock loops (PLLs) face high power consumption due to the need for frequency dividers or fast phase detection, which is inefficient in terms of energy usage.
Innovation Solution
A subsampling motion detector that employs a controllable oscillator and a subsampling phase detector (SSPD) or subsampling analog-to-digital converter (SSADC) to lock the oscillation signal to a multiple or fractional multiple of a reference frequency, reducing the need for frequency dividers and minimizing power consumption by sampling at a lower rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a frequency divider is used to divide the high frequency oscillation signal before phase detection, then the phase detection can be performed at a lower frequency, but the frequency divider consumes a great deal of power during operation
Solution Approach 1:
The patent extracts and eliminates the frequency divider component from the traditional PLL architecture. Instead of dividing the high frequency signal before phase detection, the invention directly compares the high frequency oscillation signal with a low frequency reference signal using a phase detector capable of handling high frequency inputs, thereby removing the power-consuming frequency divider while maintaining phase detection functionality
Solution Approach 2:
The invention changes the operating parameters of the phase detector to enable it to function at high frequencies without requiring signal division. The phase detector is designed or selected to operate directly with high frequency signals, changing the frequency parameter at which phase detection is performed from a divided low frequency to the original high frequency, thus eliminating the need for a frequency divider
2Device complexity
If a high frequency reference signal is provided for comparison with the high frequency oscillation signal, then the high frequency oscillation signal does not need to be divided, but the phase detector has to perform phase detection at a fast rate which could lead to increased power consumption
Solution Approach 1:
The invention inverts the traditional approach by using a low frequency reference signal instead of a high frequency reference signal. The phase detector compares the high frequency oscillation signal with this low frequency reference signal, leveraging the properties of injection locking where the low frequency reference controls the phase and frequency of the high frequency oscillation, thereby simplifying the reference signal generation while maintaining detection accuracy
Solution Approach 2:
The invention introduces the concept of injection locking as an intermediary mechanism. The low frequency reference signal acts as a mediator that indirectly controls the high frequency oscillation signal through the injection locking effect in the oscillator, allowing phase detection to occur without requiring direct high frequency reference signal generation or fast phase detection at high frequencies
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 subsampling motion detector effectively detects motion information while significantly reducing power consumption compared to traditional PLL-based systems, maintaining accuracy without the need for frequency dividers and minimizing environmental interference.
Implementation Method 1
the first wireless RF signal is injected to the controllable oscillator for controlling the controllable oscillator through injecting locking
Implementation Method 2
a subsampling phase detector (SSPD) generating a control signal according to the oscillation signal generated by the controllable oscillator and a reference frequency
Implementation Method 3
a motion detector detecting the status of displacement of an object by the Doppler Effect requires a high frequency signal output from an oscillation source
Data Source
AI summary
A subsampling motion detector configured to detect motion information of an object under measurement receives a first wireless radio frequency (RF) signal and transmits a second wireless RF signal, the first wireless RF signal being generated by reflecting the second wireless RF signal from the object. The subsampling motion detector includes a controllable oscillator outputting an oscillation signal, wherein the first wireless RF signal is injected to the controllable oscillator for controlling the controllable oscillator through injecting locking. The subsampling motion detector further including a subsampling phase detector (SSPD) generating a control signal according to the oscillation signal generated by the controllable oscillator and a reference frequency, the SSPD outputting the control signal to the controllable oscillator for controlling the controllable oscillator, the oscillation signal of the controllable oscillator being locked to a multiple of the reference frequency and the control signal representing the motion information of the object.