Virtual Radar Channel Creation via Orthogonal Waveforms
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Solution Overview
Problem
Modern airborne radars face challenges in detecting targets in the presence of false echoes and electronic jamming, particularly when ground clutter competes with targets at similar altitudes, requiring at least three transmission channels which are costly and bulky, limiting their effectiveness.
Innovation Solution
A method to create a virtual reception channel using two physical reception channels and two transmission channels, employing dynamic selection of orthogonal random noise waveforms to separate target echoes from ground clutter, reducing the level of secondary lobes through adapted filtering and phase code optimization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three transmit channels are used to detect low-speed targets hidden within ground clutter using STAP method, then detection capability is improved, but device complexity and cost increase
Solution Approach 1:
The patent creates a virtual third receive channel by processing signals from two physical receive channels through adaptive filtering and orthogonal waveform separation. This virtual copy enables STAP processing without requiring a physical third antenna element, thus maintaining detection capability while reducing hardware complexity
Solution Approach 2:
The patent transitions from spatial dimension (physical antenna elements) to temporal and signal processing dimension (orthogonal waveforms and adaptive filtering) to achieve the equivalent of a third receive channel. This dimensional transformation allows virtual channel creation without additional physical hardware
2Loss of information
If orthogonal waveforms are used to separate target echoes from ground clutter, then signal separation is improved, but sidelobe levels of compressed pulses increase
Solution Approach 1:
The patent optimizes the parameters of orthogonal waveforms (phase codes, waveform shapes, time frequencies) to achieve a balance between signal separation capability and sidelobe suppression. By carefully selecting and adjusting waveform parameters, both objectives are satisfied simultaneously
Solution Approach 2:
The patent employs adaptive filtering with feedback mechanisms that adjust waveform parameters and filtering coefficients based on the detected signal characteristics and clutter properties. This feedback loop optimizes the orthogonal waveforms to minimize sidelobes while maintaining effective signal separation
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
Enables effective detection and localization of low-speed targets competing with ground clutter using a less bulky and cost-effective antenna configuration, achieving reduced secondary lobe levels and improved radar performance.
Implementation Method 1
a radar system (20) comprising an antenna (22) having two physical receiving channels (1r, 2r) spaced a distance d apart along a direction x
Implementation Method 2
the acquisition by the receiving channels of the echoes from the pulses emitted by the transmission channels and reflected by at least one target
Data Source
Figure 1
Figure 2A~2B
Figure 3
AI summary
Method of creating a virtual receiving channel in a radar system (20) comprising an antenna having two physical receiving channels (1r, 2r) separated by a distance d along a direction x, two transmitting channels (1e, 2e) separated by the same distance d along the same direction x and processing means (26), the method comprising: the dynamic selection of two different waveforms, orthogonal to each other; the generation of a radar pulse (41, 42) of the same central wavelength in each transmitting channel, each of the transmitting channels emitting one of said two different waveforms; the acquisition by the receiving channels of the echoes from the pulses emitted by the transmitting channels and reflected by at least one target (4);the compression of the pulses by adapted filtering of the echoes acquired by each physical reception channel by performing their correlations with each of the waveforms generated in the transmission channels and radar system (31) for the implementation of such a process; and the repetition of steps a) to c) by randomly changing one of the values of each of the phase codes associated with the generated waveforms until a stabilization of the level of the side lobes of all the compressed pulses is obtained.