Multi-Channel Antenna Anti-Jamming via Zonal Signal Filtering
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Solution Overview
Problem
Current anti-jamming methods for Synthetic Aperture Radar (SAR) systems, such as the OLS technique, are ineffective against jammers located within the main lobe of the antenna, as they assume the useful signal comes from a single direction and fail to correctly dissociate interference noise due to channel gain variations and non-stationary noise conditions in multi-channel mobile antennas.
Innovation Solution
A method involving time block division, frequency subband processing, noise autocorrelation matrix estimation, and channel gain calculation to apply specific linear combinations of signals in each zone and subband, effectively canceling interference noise by adapting to the noise characteristics in each area of the observed scene.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single filter is applied to minimize interference noise power using OLS technique, then the filtering effectiveness improves for jammers in side lobes, but the method fails completely for jammers located in the main lobe due to incorrect assumption of single signal direction
Solution Approach 1:
The patent divides the observed scene into multiple zones and applies different linear combination filters to each zone. This segmentation allows the system to adapt the filtering approach according to the specific jammer location, whether in the main lobe or side lobes, thereby resolving the contradiction between reliability for specific cases and adaptability across all scenarios.
Solution Approach 2:
The patent implements dynamic adaptation of filtering parameters based on the observed scene characteristics. By calculating zone-specific linear combinations that account for channel gain variations and noise autocorrelation in different directions, the system dynamically adjusts its anti-jamming strategy to maintain effectiveness across varying jammer locations and conditions.
2Device complexity
If linear combination filtering is applied without considering channel gain variations and non-stationary noise, then the processing complexity remains low, but the interference noise cannot be correctly dissociated from the useful signal
Solution Approach 1:
The patent applies different filtering characteristics to different zones of the observed scene. By calculating zone-specific linear combinations that incorporate local channel gain variations and noise autocorrelation properties, the system achieves high signal separation accuracy in each local region while maintaining overall system manageability through the structured zonal approach.
3Measurement precision
If the radar illumination time and transmitted band are extended to achieve fine resolution, then the imaging quality improves, but the susceptibility to jamming increases as jammers have more time to generate interfering signals within the frequency band
Solution Approach 1:
The patent changes the parameters of the filtering operation by dividing the extended illumination time into multiple time blocks and applying different linear combinations to each block. This allows the system to maintain the benefits of long illumination time for fine resolution while adapting the filtering parameters to counteract jamming signals that may vary over time within the extended observation period.
Data Source
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AI summary
The method involves dividing sub-band frequencies into time blocks, and estimating an auto-correlation matrix of noise in each frequency. Gain of channels in directions corresponding to zone sections of a scene observed with an angular pitch is estimated. Signals received on the channels in each zone sections are filtered by linear combinations, where each linear combination depends on the matrix and on values of gain of the channels for each of the time blocks and each frequency, and allows to cancel interference component in the direction corresponding to the considered zone section.