Millimeter-Wave Radar Angle Estimation via Doppler Compensation
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Solution Overview
Problem
Current millimeter-wave radar systems face challenges in accurately estimating the angle of arrival of radar signals reflected from human targets due to Doppler components, which affect the precision of angle estimation, especially in cases of moving humans and vital sign-induced micro-Doppler components.
Innovation Solution
The method involves using a millimeter-wave radar system with two receiving antennas to generate range-Doppler maps, compensating for Doppler components by selecting peaks based on determined Doppler velocities, and estimating the angle of arrival through phase difference calculations using a phase mono-pulse algorithm, thereby improving the accuracy of angle estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If Doppler components are present in the radar signal, then the radar can detect moving targets and vital signs, but the angle estimation precision deteriorates
Solution Approach 1:
The patent segments the Doppler spectrum into multiple components by generating multiple range-Doppler maps at different Doppler frequencies. This allows the system to separate and process different Doppler components independently, enabling angle estimation while accounting for the presence of multiple Doppler shifts from moving targets and vital signs.
Solution Approach 2:
The patent changes the Doppler frequency parameter by generating range-Doppler maps at multiple different Doppler frequencies. This parameter transformation allows the system to compensate for Doppler effects in the angle estimation process, resolving the contradiction between detecting moving targets and maintaining angle precision.
2Measurement precision
If macro-Doppler compensation is performed by selecting peaks in range-Doppler maps, then angle estimation accuracy improves, but the processing complexity increases
Solution Approach 1:
The patent performs preliminary action by pre-computing and storing range-Doppler maps at multiple Doppler frequencies before angle estimation is needed. This allows the system to quickly select the appropriate map based on the detected peak, reducing real-time processing complexity while maintaining high angle estimation accuracy.
Solution Approach 2:
The patent creates multiple copies of the range-Doppler map at different Doppler frequencies. Instead of processing a single complex map, the system uses these replicated maps to identify peaks and perform compensation, simplifying the overall processing workflow while improving accuracy.
3Measurement precision
If multiple range-Doppler maps are generated at different Doppler frequencies, then Doppler component separation improves, but the computational load increases
Solution Approach 1:
The patent applies partial action by generating range-Doppler maps only at specific, predetermined Doppler frequencies that are most likely to contain relevant signal components. This selective approach provides sufficient Doppler component separation without the excessive computational cost of analyzing all possible frequencies.
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 accuracy of angle of arrival estimation for both static and moving humans by compensating for Doppler effects, leading to improved precision and reliability in radar signal processing, even in low signal-to-noise ratio regimes.
Implementation Method 1
transmitting a frequency modulated signal, receiving a reflection of the frequency modulated signal (also referred to as the echo)
Implementation Method 2
determining a Doppler velocity of the human target based on the reflected radar signal
Data Source
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AI summary
A method of estimating an angle of arrival of a radar signal reflected on a human target includes: receiving the reflected radar signal with first and second antennas of a millimeter-wave radar; transforming the reflected radar signal received to generate first and second range spectrum, respectively; generating a first and second range-Doppler maps based on the first and second range spectrum, respectively; determining or estimating a Doppler velocity based on the first range-Doppler map or the second range-Doppler map; compensating the first and second range-Doppler maps by selecting a peak in the first or second range-Doppler maps based on the determined Doppler velocity; identifying an index of the first macro-compensated range-Doppler map corresponding to an identified target; estimating a phase difference based on the first and second macro-compensated range-Doppler maps and the identified index; and estimating the angle of arrival based on the phase difference.