Radar Signal Processing for Minute Displacement Without DC Interference
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Solution Overview
Problem
Existing radar systems include direct-current components that interfere with the accurate acquisition of minute displacement components, such as body surface displacements, due to reflections from stationary objects.
Innovation Solution
A radar system with a first device and a second device installed at the subject of displacement acquisition, where the second device operates in two modes: reradiating and phase-delaying received radio waves, allowing the first device to calculate and remove direct-current components from acquired information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a radar system uses a radio wave sensor to acquire biological information, then biological information on a human body can be obtained, but a direct-current component from stationary objects interferes with the accurate acquisition of minute displacement components
Solution Approach 1:
The patent segments the received signal into two distinct components: a first signal component containing both direct-current and alternating-current components, and a second signal component containing only the direct-current component. By separating these components through different reception processes (one facing the target object, another facing a reference direction), the system can isolate and remove the harmful direct-current interference while preserving the useful minute displacement information.
Solution Approach 2:
The patent extracts the direct-current component from the received signal by comparing two reception paths. The second reception process, which receives radio waves in a reference direction away from the target, captures only the direct-current component from stationary objects. This extracted direct-current component is then subtracted from the first reception signal to remove the interference, leaving only the useful alternating-current component containing minute displacement information.
2Quantity of substance
If the direct-current component is large, then reflected components from stationary objects are strong, but the ability to acquire minute displacement components relative to the direct-current component deteriorates
Solution Approach 1:
The patent introduces a reference reception path as an intermediary that captures only the direct-current component from stationary objects without the minute displacement information. This intermediary signal serves as a template for the interference, allowing the system to identify and remove the harmful direct-current component from the main reception signal while preserving the useful alternating-current component containing the minute displacement information.
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
Enables accurate acquisition of minute displacement components, such as respiration or pulse, by removing direct-current interference from stationary objects.
Implementation Method 1
a radar system includes a first device that acquires a displacement of a subject of displacement acquisition by using a reception wave
Implementation Method 2
information on a phase change amount of the reflected wave based on a displacement angle of a range where the signal point is displaced on the circle with respect to a center of the circle is output
Implementation Method 3
The second device has a first mode in which the second device reradiates a received radio wave, and a second mode in which the second device delays a phase of a received radio wave and reradiates the received radio wave
Data Source
AI summary
A radar system includes a first device that acquires a displacement of the subject of displacement acquisition by transmitting and receiving a radio wave, and a second device installed at the subject capable of transmitting to and receiving from the first device. The second device has a first mode in which it reradiates a received radio wave and a second mode in which it delays a phase of a received radio wave before reradiating. The first device acquires first IQ information while the second device is operating in the first mode and second IQ information while the second device is operating in the second mode. The first device then calculates a direct-current component of the first IQ information and generates third IQ information by removing the direct-current component from the first IQ information.