Automatic Doppler Filter Selection for Radar Clutter Discrimination
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Solution Overview
Problem
Pulse-Doppler radar systems face challenges in effectively discriminating between clutter and target signals due to the complexity of bank switching and the need for multiple Doppler filter banks, which are difficult to implement and often do not select the optimum filter bank for performance.
Innovation Solution
A single Doppler filter bank with a plurality of matched Doppler filters is used to process radar returns, where each filter generates a clutter map, and a 'greatest of' operation identifies the filter with the highest signal-to-clutter ratio, eliminating the need for bank switching and optimizing filter selection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple Doppler filter banks are used to handle different clutter types, then clutter discrimination capability is improved, but device complexity and implementation difficulty increase
Solution Approach 1:
The patent merges multiple Doppler filter banks into a single filter bank containing multiple Doppler filters. Instead of maintaining separate filter banks for different clutter types and implementing complex switching logic, the invention combines all necessary filters into one unified structure that can process various clutter types without requiring bank switching controls.
Solution Approach 2:
The single Doppler filter bank is designed to perform multiple functions by containing filters matched for different clutter types (weather clutter, ground clutter, folded over clutter, etc.). Each filter within the bank can be selectively activated based on the detected clutter type, allowing one filter bank to handle multiple clutter scenarios that previously required separate dedicated banks.
2Reliability
If bank switching controls and algorithms are implemented to select optimum filter banks, then clutter suppression performance is improved, but ease of operation and implementation difficulty worsen
Solution Approach 1:
The system automatically identifies the appropriate Doppler filter to activate based on comparing filter outputs against stored clutter maps. The processor evaluates which filter produces the highest signal-to-clutter ratio by comparing against pre-stored clutter characteristics, eliminating the need for manual intervention or complex switching algorithms while maintaining optimal clutter suppression.
3Adaptability or versatility
If redundant filters are included in multiple filter banks to cover entire Doppler window, then clutter discrimination capability is improved, but quantity of filters and processing load increase
Solution Approach 1:
The patent consolidates redundant filters that would traditionally be distributed across multiple filter banks into a single integrated filter bank. By combining all necessary Doppler filters for different clutter types into one structure, the system eliminates the need for redundant filter sets while maintaining comprehensive coverage of the Doppler window.
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 simplifies the clutter suppression process, reduces the number of required filters, and ensures optimal performance by identifying the filter with the highest signal-to-clutter ratio, enhancing target detection accuracy and reducing false alarms.
Implementation Method 1
Many of these clutter cancellation methods rely on the principle that moving targets have a Doppler frequency shift, while stationary targets do not. Thus, pulse-Doppler radar systems may implement a plurality of Doppler frequency filters (e.g. FFT networks) used to divide the Doppler frequency space into many narrow regions
Data Source
AI summary
A system for suppressing clutter in a radar system is provided. The system includes an antenna configured to receive radar signals containing clutter and a digital receiver adapted to convert the radar signals received by the radar arrays to complex I/Q samples. These I/Q samples are provided to a Doppler filter bank comprising a plurality of Doppler filters for filtering the pulse compressed data into Doppler bins representative of range values according to Doppler frequency. The system further includes at least one processor for comparing the output of each of the plurality of Doppler filters types to respective background clutter maps, and identifying the Doppler filter which outputs the radar return signal with the greatest magnitude over the clutter map. Once identified, target detection operations may be performed on the output of the identified Doppler filter.