FMCW Radar Distance Velocity Ambiguity Resolution
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Solution Overview
Problem
Current FMCW radar systems face challenges in accurately determining the distances and relative speeds of multiple objects within a detection range due to increased computational effort and ambiguity in peak assignment, especially in complex scenarios like traffic jams or parking lots, where multiple objects require multiple modulation ramps for accurate detection.
Innovation Solution
The method involves modulating the transmission signal using sequences of frequency ramps with higher-level ramps having different gradients, assigning peaks in the baseband spectra to objects by analyzing intersections in the distance/velocity space, and using a two-dimensional Fourier transformation to reduce computational effort and improve detection performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple modulation ramps with different slopes are used to detect multiple objects, then measurement precision is improved, but computational effort increases
Solution Approach 1:
The patent segments the distance/velocity space into multiple regions, each associated with a specific modulation ramp. By dividing the detection space and assigning different ramps to different segments, the system can process multiple objects simultaneously with reduced computational complexity compared to analyzing all objects with all ramps.
Solution Approach 2:
The patent introduces a spatial dimension to the frequency matching process by assigning specific modulation ramps to specific regions in distance/velocity space. This dimensional approach transforms the problem from a comprehensive multi-ramp analysis to a region-specific analysis, reducing the computational burden while maintaining detection accuracy for multiple objects.
2Reliability
If more modulation ramps are used to resolve peak assignment ambiguity, then detection reliability is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by assigning specific modulation ramps to specific regions in distance/velocity space. Each region has a dedicated ramp configuration optimized for its characteristics, which simplifies the overall system management compared to using all ramps for all regions, while still providing reliable peak assignment through localized optimization.
3Adaptability or versatility
If frequency ramps with different slopes are applied, then detection versatility is improved, but frequency generation complexity increases
Solution Approach 1:
The patent segments the frequency generation task by creating distinct frequency ramp sequences for different regions in distance/velocity space. Each segment has its own optimized ramp parameters, which provides detection versatility for different scenarios while reducing overall complexity by avoiding the need to manage all possible ramp configurations simultaneously across the entire detection space.
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
This approach enhances detection performance and reduces computational requirements by allowing for more accurate and efficient assignment of peaks to objects, even in scenarios with multiple radar targets, improving the determination of distances and relative speeds while maintaining low frequency generation complexity.
Implementation Method 1
the signal reflected by an object and received back by the sensor is mixed with a portion of the signal transmitted at the time of reception to create a baseband signal
Implementation Method 2
This frequency depends on the object's distance due to changes in the transmission frequency during signal propagation time, but also on the object's relative velocity due to the Doppler effect
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention relates to an FMCW radar sensor and a method for determining information about distances and relative velocities of located objects by means of an FMCW radar, according to which method the frequency (f) of a transmitted signal is modulated in the form of sequences of frequency ramps (26), wherein within a particular sequence, the centre points of the frequency ramps (26) lie on a higher-order ramp (28); wherein for at least one frequency position (k) in frequency spectra (An) of the baseband partial signals (s), a higher-order frequency spectrum (A(k)) is determined over the temporal sequence of amplitudes at the frequency position (k) in the frequency spectra (An) of the sequence of baseband partial signals (s), wherein peaks in the at least one higher-order spectrum (A(k)) are represented by straight lines (44, 46, 48, 50) in a distance/velocity space, the respective slope of which depends on the slope of the higher-order ramp (28), and bands (40, 42) of the distance/velocity space associated with the respective peaks by means of the frequency positions (k) in the frequency spectra (An) of the baseband partial signals (s) are taken into account in the frequency matching.