Radar Angular Accuracy via Orthogonal Code Interferometry
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Solution Overview
Problem
Current radar systems face challenges in achieving high angular accuracy for obstacle sensing and avoidance, particularly in short- and medium-range applications, due to the need for large antenna surfaces and complex implementations to eliminate ambiguities, which are costly and cumbersome.
Innovation Solution
A radar device employing a colored transmission system with at least two contiguous antennas transmitting orthogonal codes and an interferometer with two receiving antennas, allowing for accurate angle measurements with reduced ambiguity through single-pulse and phase measurement principles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a large antenna surface area is used to increase range, then the range is improved, but the device complexity and size increase
Solution Approach 1:
The transmitting antenna is divided into multiple contiguous antennas (at least two), each transmitting a different orthogonal code. This segmentation allows the system to achieve high angular accuracy through interferometric measurements between the segmented antennas while maintaining a compact overall structure, resolving the contradiction between range and complexity.
Solution Approach 2:
The patent introduces orthogonal codes as an additional parameter to distinguish signals from different antennas. By multiplexing signals with orthogonal codes (e.g., phase codes, frequency codes), the system can identify and separate signals from each antenna segment, enabling accurate angle measurement without requiring a large physical antenna surface area.
2Measurement precision
If the antenna length H is increased to improve angular accuracy, then the angular accuracy is improved, but the device size increases
Solution Approach 1:
Instead of increasing the physical length H in one dimension to improve angular accuracy, the patent introduces a code dimension to distinguish signals. The orthogonal codes provide an additional degree of freedom that allows the system to achieve high angular accuracy through interferometric phase measurements between closely spaced antennas, eliminating the need for a long physical antenna structure.
3Measurement precision
If an interferometer with significantly spaced phase centres is used to obtain accurate angle measurements, then the angular accuracy is improved, but the ambiguity level increases
Solution Approach 1:
The patent uses the received signals from multiple antennas with orthogonal codes to generate feedback information about the target's angular position. By processing the phase differences and code correlations from the multiple antenna segments, the system can resolve angular ambiguities and maintain both high accuracy and low ambiguity levels simultaneously.
4Measurement precision
If multiple antennas with irregular spacing are used to eliminate angular ambiguities, then the angular accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent applies different orthogonal codes to different local antenna segments, creating a structured code distribution across the antenna array. This local differentiation allows the system to eliminate angular ambiguities through code correlation processing while maintaining a regular, simple physical antenna configuration, thus avoiding the complexity of irregular spacing.
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 accuracy with reduced size and complexity, providing accurate and unambiguous angle measurements for obstacle detection, suitable for 'Sense & Avoid' functions in non-segregated air domains.
Implementation Method 1
an interferometer comprising at least two receiving antennas (71, 72), supplying a phase measurement and therefore a second measurement of the angle of arrival of a target echo
Implementation Method 2
in transmission (21), a coloured transmission system comprising at least two contiguous antennas (1, 2, 3, 4, 5, 6), the first antenna transmitting a first code (E1) and the second antenna transmitting a second code (E2)
Implementation Method 3
filtering means (40) separating the received signals into two signals R1 and R2, the signal R1 corresponding to the first code (E1) and the signal R2 corresponding to the second code (E2)
Data Source
AI summary
The present invention relates to a radar device with high angular accuracy. The solution provided by the invention simultaneously combines an interferometer that is accurate but, for example, ambiguous when receiving; and a space coloring mode when transmitting. The coloring of the space consists notably in transmitting on N transmitting antennas N orthogonal signals. These signals are then separated by filtering on reception using the orthogonality properties of the transmission signals. It is, for example, possible, with two contiguous antennas in transmission associated with two orthogonal codes to produce a single-pulse type system when transmitting. The invention applies notably to the obstacle sensing and avoidance function, also called “Sense & Avoid”.