Standing Wave Radar for Short-Range Occupant Detection
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Solution Overview
Problem
Conventional distance measuring methods using standing wave radar struggle to detect objects at short distances due to the presence of a DC component in the distance spectrum, requiring multiple measurements and complex signal processing to remove it.
Innovation Solution
A standing wave radar system that transmits and receives signals at multiple frequencies in a time-division manner, using inverse Fourier transforms to calculate reflection coefficients and determine the presence and distance of objects, allowing for simple detection of both stationary and non-stationary objects without the need for multiple measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a Fourier transform is executed on a standing wave or mixed wave to calculate distance spectrum, then distance measurement is achieved, but a DC component corresponding to zero distance exists making short-distance object detection difficult
Solution Approach 1:
The patent extracts and removes the DC component from the distance spectrum through signal processing. By separating the AC component (which contains useful distance information) from the DC component (which causes interference at zero distance), the system eliminates the harmful effect while preserving the measurement capability. This is achieved through differentiation processing and multiple measurement points.
Solution Approach 2:
The patent divides the measurement process into multiple segments by performing measurements at multiple points. Instead of a single Fourier transform, the system executes multiple measurements at different positions and combines the results through differentiation, which segments the DC component's influence and enables short-distance detection.
2Measurement precision
If measurement is performed at multiple points with differentiation processing to remove DC component, then short-distance detection is enabled, but measurement complexity and processing time increase
Solution Approach 1:
The patent introduces dynamic frequency modulation by changing the frequency of the transmission signal over time. This dynamic approach allows the system to perform multiple measurements efficiently by varying frequency rather than requiring complex spatial segmentation, thereby reducing measurement process complexity while maintaining short-distance detection capability.
Solution Approach 2:
The patent changes the frequency parameter of the transmission signal to enable differentiation between DC and AC components. By modulating frequency over time and analyzing the resulting distance spectrum variations, the system removes the DC component's harmful effect without requiring complex multi-point spatial measurements.
3Measurement precision
If multiple frequency measurements are performed in time-division manner, then accurate distance spectrum calculation is achieved, but measurement time increases
Solution Approach 1:
The patent employs periodic frequency modulation where the transmission signal cycles through multiple frequencies in a structured time-division manner. This periodic action allows the system to efficiently collect data at multiple frequencies while maintaining a predictable and optimized measurement timeline, reducing overall measurement time compared to arbitrary sequential measurements.
Solution Approach 2:
The patent performs preliminary frequency setting and signal preparation before the actual measurement phase. By pre-configuring the frequency sequence and preparing the measurement framework in advance, the system minimizes the time required during the actual multi-frequency measurement process, achieving accurate distance spectrum calculation with reduced measurement time.
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 detection of objects at short distances by simplifying the measurement process, distinguishing between stationary and non-stationary objects, and detecting seat belt fastening through RFID tags, enhancing the system's functionality and efficiency.
Implementation Method 1
a transmitter configured to set a frequency of a transmission signal to multiple frequencies, and output the transmission signal taking the respective frequencies in a time-division manner; a receiver configured to receive a reflected signal taking the multiple frequencies in a time-division manner, the reflected signal being the transmission signal taking the multiple frequencies reflected by an object
Implementation Method 2
execute a first inverse Fourier transform process of calculating a first distance spectrum for the object by executing an inverse Fourier transform on the reflection coefficients of the multiple frequencies
Data Source
AI summary
A standing wave radar includes: a transmitter to set a frequency of a transmission signal to frequencies, and output the transmission signal taking the respective frequencies in a time-division manner; a receiver to receive a reflected signal taking the frequencies in a time-division manner, the reflected signal being the transmission signal reflected by an object; and a processor to obtain reflection coefficients of the frequencies by obtaining each reflection coefficient of the transmission signal and the reflected signal taking a same frequency, for the transmission signal and the reflected signal taking the frequencies, and to execute a first inverse Fourier transform process of calculating a first distance spectrum for the object by an inverse Fourier transform on the reflection coefficients, and a first distance measurement process of determining presence of the object and calculating a distance to the object, based on the first distance spectrum.