Nested FMCW Radar Modulation for Fine Range and Wide Velocity Detection
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Solution Overview
Problem
Conventional radar sensor systems face challenges in achieving high range and angular resolution simultaneously with large unambiguous velocity detection range due to hardware limitations such as analog-to-digital converter (ADC) sampling rates, which compromise the unambiguous velocity detection range and increase processing latency.
Innovation Solution
The use of nested frequency modulated continuous wave (N-FMCW) waveforms with multiple ramp groups and virtual ramps, combined with fast Fourier transforms (FFTs) for coarse and fine range and velocity estimation, allows for concurrent high range and angular resolution with large unambiguous velocity detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wider bandwidth radar signals are employed to achieve finer range resolution, then range resolution is improved, but unambiguous velocity detection range decreases due to increased PRI
Solution Approach 1:
The patent divides the wide bandwidth signal into multiple narrower bandwidth segments transmitted in sequence. Each segment is processed independently to achieve fine range resolution, while the segmented structure allows for shorter PRI within each segment, thereby maintaining large unambiguous velocity detection range. The segmentation principle resolves the contradiction by allowing simultaneous optimization of both range resolution and velocity detection capabilities.
Solution Approach 2:
The patent implements a nested processing structure where multiple levels of Fast Fourier Transform (FFT) are applied hierarchically. The first level FFT processes individual bandwidth segments for coarse range estimation, while subsequent nested FFT levels process combined segments for fine range estimation. This nested approach enables the system to achieve fine range resolution equivalent to wide bandwidth while maintaining the velocity detection advantages of narrower individual segments.
2Measurement precision
If wider bandwidth radar signals are used to achieve finer range resolution, then range resolution is improved, but processing latency increases due to hardware limitations
Solution Approach 1:
By segmenting the wide bandwidth signal into multiple narrower bandwidth portions that can be processed in parallel or sequential batches, the patent reduces the computational burden on ADC hardware at any given moment. This segmentation allows for faster processing of each segment while achieving the same overall fine range resolution, thereby reducing total processing latency.
Solution Approach 2:
The patent performs preliminary coarse range estimation using first-level FFT on individual bandwidth segments before conducting fine range estimation using nested FFTs. This preliminary action allows for early filtering and preprocessing of data, reducing the computational complexity of subsequent processing steps and overall processing latency.
3Measurement precision
If conventional radar signal processing is used with wide bandwidth, then range resolution is improved, but signal-to-noise ratio losses and phase noise increase
Solution Approach 1:
The patent segments the wide bandwidth signal into multiple narrower bandwidth segments, each with better signal-to-noise ratio characteristics. By processing segments individually and combining results through nested FFT, the system achieves fine range resolution while maintaining better SNR compared to processing a single wide bandwidth signal, as each narrower segment has lower noise floor and better phase stability.
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 reduces processing latency, mitigates signal-to-noise ratio (SNR) and magnitude losses, and mitigates phase noise, enabling accurate and timely object detection in various weather conditions.
Implementation Method 1
Radar sensor systems emit radar signals into a surrounding environment. The radar sensor signals reflect off objects in the environment and the radar system then detects the reflected radar signals.
Implementation Method 2
nested frequency modulated continuous wave (N-FMCW) waveforms
Data Source
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AI summary
A radar sensor comprises a transmit antenna configured to transmit a nested frequency modulated continuous wave (N-FMCW) radar waveform; a receive antenna that receives a radar return; and a hardware logic component that is configured to perform various acts. The acts comprise generating the N-FMCW radar waveform for transmission by the transmit antenna, receiving from the receive antenna a radar signal comprising the N-FMCW waveform, and sampling the N-FMCW waveform to obtain analog-to-digital (ADC) samples, the acts further comprise performing coarse range and velocity estimation for a detected object using ADC samples from ramps in the ramp groups, and performing fine range and velocity estimation using the output of the coarse range and velocity estimation. Additionally, the acts comprise outputting a coarse range and velocity map from coarse range and velocity estimation information and outputting a fine range and velocity map from fine range and velocity estimation information.