Radar Azimuth Estimation Using Virtual Echoes for Closely Spaced Targets
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Solution Overview
Problem
Radar devices face challenges in accurately estimating the azimuth and received power of adjacent targets due to limitations in azimuth resolution, leading to unreliable target information, especially when the difference in azimuths is smaller than the device's resolution, causing variations in the number and power of arrival echoes between modulation cycles.
Innovation Solution
The radar device employs a frequency-peak extracting module to analyze beat signals from multiple receiving antennas, generating autocorrelation matrices and estimating arrival azimuths and powers, with a virtual azimuth and power calculation for adjacent echoes within the resolution limit, allowing for improved azimuth information and pair-matching of frequency components across modulation cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional azimuth estimation algorithms are used, then the radar device can estimate azimuth and received power of targets, but the accuracy deteriorates when adjacent targets have azimuth differences smaller than the resolution limit
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands and processes each band separately. By dividing the frequency range into multiple segments and performing spectrum analysis on each segment independently, the system can resolve adjacent targets that would otherwise be merged into a single broad peak, thereby improving azimuth estimation accuracy for closely spaced targets.
Solution Approach 2:
The patent introduces a virtual dimension by calculating virtual arrival azimuths and virtual received powers for frequency components that cannot be directly resolved. This virtual dimension allows the system to interpolate and estimate target parameters for azimuth differences below the physical resolution limit, effectively extending the measurement capability beyond the hardware resolution constraint.
2Measurement precision
If frequency-peak extracting module analyzes beat signals from multiple receiving antennas, then the system can separate adjacent targets within resolution limit, but the device complexity increases
Solution Approach 1:
The patent merges the data from multiple receiving antennas by forming a composite beat signal that incorporates information from all antennas. Instead of processing each antenna separately, the system combines the signals and performs spectrum analysis on the merged signal, reducing the computational burden while still achieving high azimuth resolution through the combined information from multiple antennas.
Solution Approach 2:
The patent performs preliminary frequency filtering and signal conditioning before the main spectrum analysis. By pre-processing the beat signals to identify and isolate frequency components of interest, the system reduces the complexity of subsequent processing steps and focuses computational resources only on the relevant frequency bands, thereby managing complexity while maintaining high resolution.
3Loss of information
If the radar device performs pair-matching of frequency components, then the system can extract target information, but variations in number and power of arrival echoes occur between modulation cycles
Solution Approach 1:
The patent implements feedback mechanisms that continuously monitor and adjust the pair-matching process. By comparing the extracted target information across multiple modulation cycles and using this feedback to refine the matching criteria, the system compensates for variations in echo characteristics and maintains consistent target information extraction even when the number or power of arrival echoes fluctuates.
Solution Approach 2:
The patent dynamically adjusts matching parameters such as the threshold for frequency component similarity and the weight given to different frequency bands based on the current signal conditions. By adapting these parameters in real-time according to the observed echo characteristics, the system maintains stable target information extraction despite variations in the number and power of arrival echoes between modulation cycles.
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 reliability of target information by accurately separating and matching frequency components, even when adjacent targets have azimuth differences within the resolution limit, maintaining high accuracy and stability in distance and speed calculations.
Implementation Method 1
Radar devices are often used as driving support devices for motor vehicles. FM-CW (Frequency-Modulated Continuous Wave) radar devices are well known as such radar devices.
Implementation Method 2
The echoes are generated by reflection of the radar wave from a target, such as a point of an object that has reflected the radar wave.
Implementation Method 3
an FM-CW radar device of this type mixes the transmit signal with received signals (received echoes) to generate beat signals.
Implementation Method 4
receive, as received signals, arrival echoes (arrival waves) by respective receiving channels of a receiving antenna
Data Source
AI summary
In a radar device, an azimuth estimating module estimates, when there are a plurality of arrival echo and an angular range between the arrival azimuth of one of adjacent arrival echoes in the plurality of arrival echoes and the arrival azimuth of the other thereof is equal to or smaller than a predetermined azimuth resolution of a plurality of receiving antennas, a virtual azimuth and virtual power for each of first frequency components and second frequency components. The virtual azimuth is within the angular range between the arrival azimuth of one of adjacent arrival echoes in the plurality of arrival echoes and the arrival azimuth of the other thereof, and the virtual power is received power of a virtual arrival echo from the virtual azimuth.