FCM Radar Rainfall Detection via 2D FFT Analysis
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Solution Overview
Problem
Existing FCM radar devices cannot determine rainfall without additional sensors like raindrop sensors, as they use a different transmission signal modulation scheme compared to FMCW radar devices.
Innovation Solution
A vehicle radar device equipped with a frequency analysis unit performing two-dimensional fast Fourier transforms on beat signals to extract peaks within a predefined distance-velocity region, allowing rainfall determination without additional sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If FCM modulation scheme is used in radar device, then radar wave transmission efficiency is improved, but rainfall detection capability deteriorates
Solution Approach 1:
The patent applies parameter changes by modifying the signal processing approach specifically for FCM modulation. It introduces a two-dimensional FFT analysis that examines both distance and velocity dimensions, and changes the detection parameters to identify raindrop-specific velocity ranges (typically -5 to 5 m/s) that differ from vehicle targets. This allows the FCM radar to maintain its transmission efficiency while gaining rainfall detection capability through adjusted analysis parameters.
Solution Approach 2:
The patent employs dimensionality change by transitioning from traditional one-dimensional range analysis to two-dimensional range-velocity analysis. By adding the velocity dimension through Doppler effect analysis, the system can distinguish raindrops (which exhibit characteristic velocity patterns) from other targets. This dimensional expansion enables rainfall detection without compromising the FCM modulation's transmission efficiency.
2Measurement precision
If additional rainfall detectors are added to FCM radar device, then rainfall detection capability is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by enabling the FCM radar device to perform multiple functions: both its original primary function of detecting vehicle targets and the additional function of rainfall detection. Through the two-dimensional FFT processing and velocity-based target classification, the same radar hardware detects both vehicle targets and raindrops, eliminating the need for separate rainfall sensors and reducing overall system complexity.
Solution Approach 2:
The radar device performs self-service by using its own transmitted FCM signals and received echoes to detect rainfall, without requiring external or additional sensors. The system processes its own signal data through the two-dimensional FFT analysis to extract rainfall information, making the rainfall detection capability intrinsic to the radar system itself rather than requiring separate dedicated hardware.
3Measurement precision
If two-dimensional fast Fourier transform is performed on beat signal, then rainfall detection accuracy is improved, but signal processing time increases
Solution Approach 1:
The patent applies preliminary action by pre-defining velocity range thresholds for raindrop detection (e.g., -5 to 5 m/s) and pre-establishing the two-dimensional FFT processing framework. These preliminary configurations allow the system to quickly filter and identify raindrop targets without performing exhaustive analysis on all possible velocity ranges, thereby reducing processing time while maintaining detection accuracy.
Solution Approach 2:
The system applies partial action by focusing the two-dimensional FFT analysis specifically on velocity ranges characteristic of raindrops (typically -5 to 5 m/s) rather than analyzing the entire velocity spectrum. This selective analysis of the relevant velocity portion enables efficient rainfall detection without the computational overhead of processing all possible target velocities, balancing accuracy with processing speed.
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 rainfall detection using FCM radar devices onboard vehicles, enhancing driving assistance systems by providing real-time rainfall information without the need for additional sensors.
Implementation Method 1
a radar device for a vehicle, capable of transmitting radar waves modulated in frequency according to an FCM modulation scheme and detecting targets by receiving the radar waves reflected by the targets
Implementation Method 2
the frequency of the transmission signal is modulated by gradually increasing or decreasing the frequency from a start frequency to an end frequency, and such modulation is repeated in a stepwise manner
Implementation Method 3
The frequency analysis unit is configured to perform a two-dimensional fast Fourier transform on a beat signal that is a frequency difference signal between transmission and reception signals of the radar waves
Implementation Method 4
extracting, from peaks of a power spectrum calculated by the two-dimensional fast Fourier transform in the frequency analysis unit, peaks within a predefined distance-velocity region preset as a raindrop condition
Data Source
AI summary
A radar device for a vehicle includes a frequency analysis unit, a peak information acquisition unit, and a rainfall determination unit. The frequency analysis unit performs a two-dimensional fast Fourier transform on a beat signal, and the peak information acquisition unit extracts, from peaks of a power spectrum calculated by the two-dimensional fast Fourier transform, peaks within a predefined distance-velocity region preset as a raindrop condition, and acquire peak information. The rainfall determination unit determines whether a surrounding environment of the vehicle has rainfall, based on the peak information acquired by the peak information acquisition unit.