Automotive Radar Doppler Filtering for Range Migration Mitigation
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Solution Overview
Problem
Existing automotive radar systems face challenges in efficiently mitigating range migration, which degrades Doppler processing and reduces target resolution due to high relative speeds, especially in high-range resolution systems, requiring computationally expensive and complex techniques like Keystone Transform (KST) to correct range migration.
Innovation Solution
Implementing a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies, using a frequency-scaled discrete Fourier transform (DFT) to directly process ADC samples, allowing for efficient range migration mitigation by computing corrected Doppler spectrums before applying fast-time FFT, thereby eliminating the need for interpolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Keystone Transform (KST) is used to correct range migration, then range migration mitigation is achieved, but computational complexity and processing time increase significantly
Solution Approach 1:
The patent changes the processing sequence parameter by performing Doppler processing before range processing, opposite to the conventional approach. This parameter change fundamentally alters the computational path, avoiding the need for complex Keystone Transform operations while still achieving range migration mitigation through the modified processing order and scaling factor application.
Solution Approach 2:
The patent inverts the conventional processing order by performing Doppler processing (slow-time FFT) before range processing (fast-time FFT), whereas traditional methods perform range processing first. This inversion, combined with applying a scaling factor to the Doppler frequencies, eliminates range migration effects without requiring the computationally expensive KST algorithm.
2Measurement precision
If small range cells are used to provide high-range resolution, then range resolution is improved, but range migration becomes more severe due to high relative speeds
Solution Approach 1:
The patent applies a scaling factor to the Doppler frequencies based on the range cell index, which compensates for the range migration effect caused by high relative speeds. This parameter transformation allows targets to remain within the same range cell throughout the coherent processing interval, maintaining both high range resolution and reliable Doppler coherent integration.
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 computational efficiency and speed while effectively mitigating range migration, improving signal-to-noise ratio and target resolution, particularly in high-speed target detection environments.
Implementation Method 1
radar-based detection to provide reliable and accurate details of a vehicle's surroundings
Implementation Method 2
when the transmitted radar signal hits a target and is reflected back to the vehicle
Implementation Method 3
modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
A linear chirp radar system, apparatus and method use a radar control processing unit to control an LFM radar front end which generates analog-to-digital (ADC) sample signals from one or more target return signals received in response to transmitted linear chirp radar signals, where the radar control processing unit is connected and configured to mitigate range migration by directly filtering the ADC samples using a modified Doppler filter that is tuned to fast-time scaled, slow-time frequencies to generate a focused ADC Doppler cube, and by applying a Fourier Transform on each Doppler cell in the focused ADC Doppler cube to generate a focused range-Doppler cube.