Radar Signal Processing for Spectrally Notched Data
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Radar systems face challenges in operating effectively in spectrally congested environments due to susceptibility to radio frequency interference (RFI), which can lead to degraded imagery and interference with other critical systems, and existing methods like RSM and CLEAN algorithms are inadequate when a large fraction of the frequency band is notched.
Innovation Solution
A novel methodology that employs a modified CLEAN algorithm, referred to as CLEAN-Notch, combined with a non-linear sidelobe-reduction algorithm, specifically designed to process spectrally-notched radar data, to mitigate the effects of frequency notching and improve radar imagery quality by eliminating downrange sidelobes and artifacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency bands are notched to avoid RFI, then interference with other systems is reduced, but radar imagery quality degrades due to sidelobes and artifacts
Solution Approach 1:
The patent converts the harmful sidelobes and artifacts caused by frequency notching into beneficial information by using them as input for the CLEAN algorithm. The algorithm iteratively identifies and removes these notching-induced artifacts, transforming the degraded imagery into high-quality output. This approach turns the previously harmful spectral notching effects into a manageable processing challenge that ultimately improves imagery quality.
Solution Approach 2:
The patent applies preliminary signal processing steps before final image formation to mitigate the effects of frequency notching. By pre-identifying and characterizing the notching patterns, the system can apply appropriate correction algorithms in advance, preventing artifact formation rather than dealing with them after image creation.
2Manufacturing precision
If conventional RSM or CLEAN algorithms are used, then sidelobes are reduced in un-notched data, but they are ineffective when a large fraction of the frequency band is notched
Solution Approach 1:
The patent modifies the CLEAN algorithm specifically to handle notched frequency data by changing its operational parameters and processing steps. The adapted algorithm accounts for the missing spectral information by adjusting how it identifies targets and removes sidelobes, making it effective in environments where traditional versions would fail.
Solution Approach 2:
The patent segments the frequency spectrum into notched and un-notched portions, treating each differently in the processing pipeline. By identifying which frequency bands are affected by notching, the algorithm can apply appropriate processing strategies to each segment, maintaining effectiveness across the entire spectrum despite partial data loss.
3Reliability
If frequency sweep omits RFI bands, then RFI susceptibility is reduced, but data gaps in frequency domain create sidelobes in time domain
Solution Approach 1:
The patent converts the harmful range sidelobes caused by frequency domain gaps into beneficial processing opportunities. By using the CLEAN algorithm to identify and remove these sidelobes, the system transforms the degraded range profiles into accurate target representations, effectively turning the RFI avoidance strategy's byproduct into a manageable artifact.
Data Source
AI summary
Embodiments of the present invention implement a novel methodology for processing radar image data from a radar system having one or more transmitter and receiver antenna pairs. The novel methodology deliberately operates on spectrally-notched radar data. It uses a specially-adapted version of the CLEAN algorithm to mitigate the effects of frequency-band notching. Following that, it performs a non-linear sidelobe-reduction algorithm to further eliminate artifacts and produce radar imagery of much higher quality. In some cases, it exploits a specific version of the recursive sidelobe minimization (RSM) algorithm which operates in the frequency and aperture (spatial) domain.