MIMO FMCW Radar Angle Estimation Phase Compensation
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Solution Overview
Problem
MIMO radar systems face challenges in achieving accurate angle estimation due to phase shifts caused by object movements, particularly when using time-division multiplexing, which limits the precision of angle determination.
Innovation Solution
The method involves relating baseband signals from multiple switching states to a common reference point in time, eliminating phase shifts without requiring exact relative speed measurements, thereby enhancing the accuracy of angle estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If time-division multiplexing is used in MIMO radar systems, then device complexity is reduced and ease of operation is improved, but measurement precision of angle estimation deteriorates due to phase shifts caused by object movements
Solution Approach 1:
The patent applies preliminary action by estimating the relative velocity of objects before performing angle estimation. The system first determines relative velocity information from the radar signals, then uses this information to compensate for phase shifts in subsequent angle calculations. This preliminary velocity estimation enables the system to correct for motion-induced phase errors, thereby maintaining measurement precision while using time-division multiplexing
Solution Approach 2:
The patent implements feedback by using estimated relative velocity information to adjust and compensate phase shifts in the angle estimation process. The system continuously monitors object motion through velocity estimation and feeds this information back into the angle calculation algorithm, dynamically correcting for phase shifts caused by object movements between different switching states
2Measurement precision
If phase shift compensation based on relative velocity estimation is implemented, then measurement precision of angle estimation is improved, but device complexity increases
Solution Approach 1:
The patent applies universality by using the same radar antenna elements and signal processing hardware for multiple functions: transmitting radar signals, receiving echoes, estimating relative velocity, and determining angle of arrival. The system performs velocity estimation and angle estimation with a unified processing framework, avoiding the need for separate dedicated hardware components for each function, thereby limiting the increase in device complexity
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 allows for more precise angle estimation in MIMO radar systems by compensating for phase shifts caused by object movements, improving the system's angular resolution and accuracy.
Implementation Method 1
A ramp-shaped frequency-modulated radar signal is transmitted
Implementation Method 2
Due to the Doppler effect, the frequency difference also includes a component caused by the object's relative velocity
Implementation Method 3
the frequency difference depends on the signal's travel time from the radar sensor to the object and back, and thus on the object's distance
Data Source
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AI summary
A method for locating objects using a MIMO FMCW radar, wherein – a ramp-shaped frequency modulated radar signal is transmitted, the modulation pattern of which has a sequence of time offset successive ramps (48, 50, 52), – switching is carried out periodically between at least two switching states (TX) with the clock of the successive ramps, which switching states differ in the selection of the antenna elements used for transmission and reception, – received radar echoes are mixed down with the transmitted signal into a baseband, – the baseband signals obtained for the various switching states (TX) are transformed into spectra, on the basis of which the distances and relative speeds of the radar targets are determined, and – the phases of the baseband signals obtained for various switching states are compared to one another for determining locating angles of the radar targets, characterized in that – the baseband signals are separately subjected to a two-dimensional Fourier transform for each switching state (TX), wherein a ramp-for-ramp transform is carried out in the first dimension and a transform is carried out over a ramp index j in the second dimension, which ramp index counts the ramps (48, 50, 52) within the sequence, using window functions which contain the wave forms of the baseband signals except for a displacement along the time axis, and – the spectra obtained for various switching states are subjected to a frequency-dependent phase correction, which compensates the time offset of the ramps.