FMCW Radar Phase Modulation for Angular Resolution
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Solution Overview
Problem
Current radar systems for automotive applications face challenges in achieving high angular resolution with a small form factor and low cost, as they require a large number of receivers and antennas, leading to increased hardware complexity and cost, particularly in advanced driving assistance systems and autonomous driving.
Innovation Solution
A frequency-modulated continuous wave (FMCW) radar system using multiple antennas with specific phase modulation schemes to separate signals from different transmitters, allowing for high angular resolution with a smaller number of components, achieved through phase shifters that apply distinct phase differences to each chirp transmitted via multiple transmit branches, enabling efficient signal processing to determine the angle of direction of targets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a large number of receivers and antennas are used to achieve high angular resolution, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the transmission function across multiple transmit branches, where each branch transmits phase-modulated chirps simultaneously. This allows the system to achieve high angular resolution through phase coding rather than requiring a large number of receivers and antennas, thereby reducing hardware complexity while maintaining measurement precision
Solution Approach 2:
The patent changes the phase parameter of transmitted chirps across different transmit branches using distinct phase modulation schemes. By varying phase differences between branches and utilizing asymmetric spectral distances in the Doppler domain, the system can resolve angular information with fewer hardware components, resolving the contradiction between measurement precision and device complexity
2Measurement precision
If a large number of receivers and antennas are used to achieve high angular resolution, then measurement precision is improved, but cost increases
Solution Approach 1:
The patent divides the transmission function across multiple low-cost transmit branches with phase modulators, replacing the need for expensive large-scale receiver arrays and antenna systems. This segmentation approach achieves high angular resolution through intelligent signal processing rather than brute-force hardware scaling, thereby reducing manufacturing cost
Solution Approach 2:
The patent uses multiple transmit branches to create virtual signal paths with different phase characteristics. By copying and phase-modulating the same base chirp signal across multiple branches, the system synthesizes angular information without requiring proportional increases in expensive hardware components
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 enables high angular resolution with reduced hardware requirements, minimizing costs and complexity while maintaining high performance, suitable for applications in autonomous driving and other high-definition imaging needs.
Implementation Method 1
a waveform generator, configured to generate a frequency-modulated continuous wave (FMCW) signal. The FMCW signal includes a set of chirps
Implementation Method 2
The plurality of phase shifters are configured to shift a phase of each chirp on at least one transmit branch
Implementation Method 3
The at least one mixer is configured to down-convert a received signal on at least one antenna to generate an intermediate frequency signal
Implementation Method 4
The FFT processing unit is configured to perform first FFT processing on each chirp received on each antenna in the digital domain and perform second FFT processing on results of the first FFT processing over the set of chirps
Data Source
AI summary
A radar system includes first, second, and third transmitter branches. The first transmitter branch transmits a first frequency-modulated continuous wave (FMCW) signal having a first set of chirps having a first phase setting such that phase values of consecutive chirps differ by a first phase difference. The second transmitter branch transmits a second FMCW signal having a second set of chirps having a second phase setting such that phase values of consecutive chirps differ by a second phase difference. The third transmitter branch transmits a third FMCW signal having a third set of chirps having a third phase setting such that phase values of consecutive chirps differ by a third phase difference. The first phase difference, the second phase difference, and the third phase difference are different phase differences. The first phase difference, the second phase difference, and the third phase difference are asymmetrically distributed relative to each other.