Automotive Radar Signal Processing Resolving Range-Walking
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Solution Overview
Problem
Standard Range-Doppler processing in automotive radar systems faces limitations due to range-walking and Doppler ambiguity issues, especially with increased range resolution and object movement speeds, which affect signal-to-noise ratio and accuracy.
Innovation Solution
A method involving a radar system that processes received pulses by performing a slow-time FFT, followed by interpolation to convert Doppler bins to velocity bins, and then a fast-time FFT to convert fast-time indices to range bins, generating a 2D matrix with velocity and range indices to accurately determine target distance and velocity, while optionally using FMCW or OFDM signals and MIMO configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard Range-Doppler processing is used, then the radar system can detect targets with basic accuracy, but range-walking and Doppler ambiguity problems occur when range resolution is increased or object speeds increase
Solution Approach 1:
The patent changes the processing parameters by introducing a new sequence of operations: slow-time FFT followed by 1D interpolation along Doppler bins, then fast-time FFT. This parameter change in the signal processing sequence resolves the range-walking problem that occurs with standard RD processing when high range resolution is required, thereby maintaining both measurement precision and reliability
2Productivity
If standard Range-Doppler processing is used, then the radar system can process signals efficiently, but Doppler ambiguity problem occurs especially when multiple transmit antennas are used
Solution Approach 1:
The patent segments the velocity measurement process into distinct stages: first performing slow-time FFT to get Doppler bins, then applying 1D interpolation to resolve Doppler ambiguity, and finally performing fast-time FFT for range measurement. This segmentation allows the system to maintain processing efficiency while eliminating Doppler ambiguity that plagues standard RD processing with multiple TX antennas
3Speed
If the radar system handles increased object movement speeds, then the radar can detect faster moving targets, but range-walking problem occurs which limits achievable signal-to-noise ratio
Solution Approach 1:
The patent applies preliminary action by performing the slow-time FFT and 1D interpolation before the fast-time FFT. This preliminary processing step corrects for range-walking effects caused by high-speed target movement before the final range measurement is taken, thereby maintaining both the ability to detect fast-moving targets and achieving high signal-to-noise ratio
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 the radar system's ability to resolve range and velocity ambiguities, improving signal-to-noise ratio and accuracy in detecting target distances and velocities, even under conditions of increased object movement.
Implementation Method 1
Radar (RAdio Detection And Ranging) has been used for a long time in both military and commercial applications
Implementation Method 2
receiving, at a receive antenna, at least some of the plurality of pulses that are transmitted towards and reflected from the target
Implementation Method 3
The range to a target can be found by detecting a frequency difference between the received and emitted radar signals. The range to the target is proportional to this frequency difference, which is also referred to as the beat frequency
Data Source
AI summary
A radar system transmits pulses towards a target and receives pulses reflected back therefrom. Based on samples (of the received pulses) corresponding to a CPI, a first 2D matrix having a slow-time index and a fast-time index is generated. A slow-time FFT is performed to convert the slow-time index to a Doppler bin index to produce a second 2D matrix having the Doppler bin index and the fast-time index. Thereafter, a 1D interpolation is performed along the Doppler bin index to produce a third 2D matrix having a Velocity bin index and the fast-time index. Thereafter, a fast-time FFT is performed to convert the fast-time index to a Range bin index to produce a fourth 2D matrix having the Velocity bin index and a Range bin index. A distance to and a velocity of a target is determined based on the fourth 2D matrix.