Vehicle Radar Ghost Removal Using Unequal Antenna Spacing
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Solution Overview
Problem
Radar apparatuses for vehicles face challenges in accurately distinguishing between real targets and grating lobe ghosts due to ambiguous angle estimation and reduced angle resolution performance, especially when antenna intervals approach half a wavelength, leading to errors in target sensing and SNR reduction.
Innovation Solution
The radar apparatus employs a combination of linearly and unequally spaced receiving antennas, along with a signal processing unit that uses digital beamforming to differentiate between real targets and grating lobe ghosts by calculating gain differences and angular power spectrum widths, allowing for the removal of grating lobe ghosts and accurate target identification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the interval between receiving antennas is increased above half wavelength, then the angle of view coverage is improved, but grating lobe ghosts appear causing target detection errors
Solution Approach 1:
The receiving antenna array is segmented into two different configurations: an equally spaced arrangement for broad angle coverage and a unequally spaced arrangement for ghost elimination. By processing signals from both configurations separately and comparing results, the system achieves both wide coverage and high detection accuracy.
Solution Approach 2:
The antenna spacing parameter is changed between two configurations: equal spacing (d) for primary scanning and unequal spacing (d1, d2, ...) for verification. This parameter variation allows the system to distinguish real targets from grating lobe ghosts by comparing angular power spectra from different spacing patterns.
2Reliability
If the interval between receiving antennas is narrowed to half wavelength or less, then grating lobe ghosts are eliminated, but the main beam becomes wide causing angle resolution performance reduction
Solution Approach 1:
The antenna array is divided into multiple sub-arrays with different spacing characteristics. The equally spaced sub-array provides fine angle resolution, while the unequally spaced sub-array provides ghost-free detection. Results from both segments are combined to achieve superior overall performance.
Solution Approach 2:
The system merges the angular power spectra obtained from equally spaced antenna reception and unequally spaced antenna reception. By combining these complementary measurements, the system achieves both high angle resolution and reliable ghost elimination.
3Ease of operation
If digital beamforming is performed with equal antenna spacing, then angle estimation is simplified, but grating lobe ghosts appear in the angular power spectrum
Solution Approach 1:
The unequally spaced antenna configuration acts as an intermediary verification mechanism. Its angular power spectrum serves as a reference to identify and eliminate false targets (ghosts) detected by the equally spaced configuration, while preserving genuine target information.
Solution Approach 2:
The system uses feedback comparison between angular power spectra from equal and unequal spacing configurations. Targets detected in both configurations are identified as real, while those appearing only in the equal spacing spectrum are identified as ghosts and eliminated.
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 effectively removes grating lobe ghosts, enhancing target sensing accuracy and maintaining driving safety, particularly during constant speed control, and ensures secure driving convenience for autonomous vehicles by distinguishing real targets from ghosts.
Implementation Method 1
a radar apparatus for vehicle, which senses a target positioned in front of a vehicle by including a plurality of transmitting antennas and a plurality of receiving antennas
Implementation Method 2
a signal processing unit configured to remove a grating lobe ghost by using a difference of a gain obtained through a digital beamforming result
Data Source
AI summary
The present disclosure relates to a radar apparatus for vehicle and a method of removing a ghost of the radar apparatus for vehicle by determining a grating lobe ghost based on a reception signal received through linearly and equally spaced receiving antennas and unequally spaced receiving antennas. The radar apparatus comprises: a transmitting unit configured to transmit a predetermined transmission signal to the front of the vehicle through the plurality of transmitting antennas; a receiving unit configured to receive a reception signal generated from the transmission signal transmitted by the transmitting unit and reflected and returned by the target positioned in front of the vehicle through the plurality of receiving antennas and the additionally included receiving antenna; and a signal processing unit configured to remove a grating lobe ghost by using the difference of a gain obtained through a digital beamforming result and the reception signal.