Direction-of-Arrival Estimation Using Arrival Time Difference
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Solution Overview
Problem
Existing direction of arrival estimation techniques face limitations due to ambiguity in phase differences between sub-array beams, leading to restricted estimable ranges and potential false target detection, especially when the distance between sub-array beams is fixed, which affects accuracy and can result in erroneous target direction estimation.
Innovation Solution
The proposed solution involves a direction of arrival estimation apparatus and method using first and second sub-arrays with phasing parts to generate sub-array beams, calculating correlations at specific time points to determine arrival time differences, and subsequently calculating the direction of arrival based on these differences, thereby eliminating the restriction on estimable ranges and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If phase difference between sub-array beams is used for direction estimation, then processing load is reduced, but estimation range is restricted and false targets may occur
Solution Approach 1:
The reception array is divided into multiple sub-arrays, and direction estimation is performed independently for each sub-array. This segmentation allows the system to maintain low processing load while expanding the overall estimation range by combining results from multiple sub-arrays.
Solution Approach 2:
The patent introduces a new dimension to direction estimation by calculating arrival time differences in addition to phase differences. This multi-dimensional approach resolves the ambiguity inherent in single-dimension phase difference methods, eliminating false targets while maintaining computational efficiency.
2Measurement precision
If fine scanning is performed to enhance calculation accuracy, then direction resolution is improved, but processing load increases
Solution Approach 1:
Instead of performing exhaustive fine scanning across all directions, the patent applies partial action by focusing computational resources only on directions identified as promising through initial coarse scanning. This reduces processing load while maintaining high direction resolution where it matters most.
Solution Approach 2:
The patent performs preliminary coarse scanning to identify candidate directions before conducting detailed fine scanning. This preliminary action filters out irrelevant directions, reducing the number of calculations required for high-precision estimation and thereby lowering overall processing load.
3Adaptability or versatility
If distance between sub-array beams is increased, then estimation range is expanded, but phase difference ambiguity increases
Solution Approach 1:
The patent introduces arrival time difference calculation as an intermediary parameter that mediates between sub-array beams with large spacing. This intermediary measurement resolves the phase difference ambiguity that arises from increased beam separation, allowing expanded estimation range without sacrificing accuracy.
Solution Approach 2:
The patent changes the measurement parameter from solely phase difference to a combination of phase difference and arrival time difference. This parameter change enables the system to handle larger sub-array beam separations while maintaining measurement precision through the complementary information provided by arrival time differences.
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 accurate direction of arrival estimation without the limitations imposed by the distance between sub-array beams, improving target direction precision and reducing false target detection, while maintaining a low processing load.
Implementation Method 1
first and second phasing parts that perform phasing of a plurality of reception signals received at the first and second sub-arrays to generate first and second sub-array beams
Implementation Method 2
an arrival time difference calculation part that calculates first and second correlations of the reception signals of the first and second sub-array beams at time points including at least first and second time points and performs a predetermined operation on the first and second correlations to find an arrival time difference
Implementation Method 3
d sin θ is a difference in distances to a target between the right beams and the left beams
Implementation Method 4
a direction of arrival calculation part that calculates a direction of arrival of the target based on the arrival time difference
Data Source
AI summary
A direction of arrival estimation apparatus includes at least first and second sub-arrays to receive a reflected wave of a transmission waveform from a target; first and second phasing parts that perform phasing of reception signals at the first and second sub-arrays to generate first and second sub-array beams; an arrival time difference calculation part that calculates first and second correlations of the reception signals of the first and second sub-array beams at first and second time points to find an arrival time difference between times of the reflected wave arriving at the first and second sub-arrays, based on a result of a predetermined operation on the first and second correlations and a time difference between the first time point and the second time point; and a direction of arrival calculation part that finds a direction of arrival of the target based on the arrival time difference.