Ambiguous Target Velocity Estimation Using Dual-Frequency FMCW Radar
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Solution Overview
Problem
Existing automotive radar systems face challenges in simultaneously optimizing maximum sensing range, range resolution, and maximum sensing velocity due to the constrained relationship between these parameters, limiting the accuracy of velocity estimation for targets.
Innovation Solution
A method involving the alternated transmission of first and second waveform signals at different center frequencies, processing intermediate frequency signals to generate Range-Doppler matrices, and estimating target velocity and range through phase convolutions, without requiring phase compensation, using Doppler frequency shift differences to enhance estimation accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FMCW radar uses carrier frequency shift for velocity estimation, then velocity measurement is enabled, but the amount of frequency shift is constrained due to phase convolutions, limiting the maximum sensing velocity range
Solution Approach 1:
The patent segments the velocity estimation process into two parts: first obtaining a preliminary velocity estimate from the Range-Doppler matrix, then using this estimate to calculate and compensate for the phase convolution effect. This segmentation allows the system to handle large velocity values by breaking down the estimation into manageable steps, thereby expanding the maximum sensing velocity range while maintaining accuracy.
Solution Approach 2:
The patent performs preliminary velocity estimation using the Range-Doppler matrix before applying phase compensation. This preliminary action provides an initial velocity value that is then used to calculate the phase convolution, enabling the system to correctly interpret phases even for high-velocity targets that would otherwise cause ambiguity.
2Measurement precision
If radar parameters are optimized for maximum sensing range and range resolution, then these parameters are improved, but the maximum sensing velocity is constrained due to the mutually constrained relationship between parameters
Solution Approach 1:
The patent changes the approach to velocity measurement by introducing phase compensation based on preliminary velocity estimates. This parameter change in the measurement methodology allows the radar to maintain optimized waveform parameters for range resolution while simultaneously achieving accurate velocity measurement for high-speed targets through the phase correction mechanism.
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 method allows for flexible waveform design parameters, improves velocity estimation reliability, and resolves ambiguities in velocity estimation by joint estimation, enhancing the accuracy of automotive radar systems.
Implementation Method 1
a Doppler frequency shift of the second waveform signal
Implementation Method 2
by using frequency modulated continuous wave (FMCW) of a carrier frequency shift
Data Source
AI summary
The present application relates to a method for estimating an ambiguous velocity of a target. The method includes: alternately transmitting a first waveform signal and a second waveform signal at a first center frequency and a second center frequency respectively; processing intermediate frequency signals of the first waveform signal and a second waveform signal to generate a first Range-Doppler matrix and a second Range-Doppler matrix respectively; acquiring the quantity of phase convolutions based on a phase difference between the first Range-Doppler matrix and the second Range-Doppler matrix and a beat frequency of the second waveform signal; and estimating a target velocity and a target range through the quantity of phase convolutions. The method has the following beneficial effects; an aliased region and velocity estimation are further improved by using information from a Doppler frequency shift difference, so that the estimation of the ambiguous velocity is more reliable.