Radar Recurrence Frequency Optimization for Clutter Rejection
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Solution Overview
Problem
Radar systems face challenges in distinguishing between target echoes and diffuse atmospheric echoes, such as those from rain, which lead to signal desensitization and reduced detection range due to clutter noise and distance ambiguities.
Innovation Solution
The method involves selecting a medium recurrence frequency (MFR) waveform with pulse compression, optimizing recurrence frequencies to minimize signal loss and desensitization caused by distance and speed eclipses, and using a combination of enumeration and gradient algorithms to determine the best frequency for radar operation, thereby reducing the impact of atmospheric clutter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Doppler filtering is used to separate clutter and targets, then target detection capability is improved, but radar detection is desensitized and range is degraded due to noise on clutter
Solution Approach 1:
The patent changes the recurrence frequency parameter of the radar pulses to optimize the balance between clutter rejection and target detection sensitivity. By selecting specific recurrence frequencies, the system minimizes the noise floor elevation caused by atmospheric clutter while maintaining adequate Doppler discrimination capability for target detection.
2Measurement precision
If pulse duration is increased to improve detection sensitivity, then detection range is extended, but distance resolution is degraded due to pulse compression effects
Solution Approach 1:
The patent utilizes periodic pulse transmission with optimized recurrence frequencies to achieve both good distance resolution and detection sensitivity. The periodic structure allows for effective pulse compression while maintaining adequate pulse duration for sensitivity, resolving the contradiction through temporal periodicity rather than single pulse duration extension.
3Manufacturing precision
If recurrence frequency is increased to improve distance resolution, then distance discrimination is improved, but speed discrimination is degraded due to Doppler frequency folding
Solution Approach 1:
The patent optimizes the recurrence frequency parameter to achieve a balance between distance resolution and speed discrimination. By selecting specific recurrence frequencies within a defined range, the system maximizes distance resolution while minimizing Doppler frequency folding that would degrade speed discrimination capability.
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 enhances radar detection performance by improving distance resolution and maintaining good speed discrimination, allowing for more accurate target detection in the presence of diffuse atmospheric echoes.
Implementation Method 1
the radar, of the pulse compression type, emitting towards the targets a wave in the form of a train of pulses...Ei, Ei+1...
Implementation Method 2
Doppler filtering conventionally makes it possible to separate the clutter and the targets because of their usually different speeds
Implementation Method 3
the backscatter of atmospheric echoes is not very strong, since the distance can be very small, the received levels can be very strong
Data Source
Figure 1~2b
Figure 3~5
Figure 6a~6c
AI summary
The method involves determining recurrence frequencies minimizing loss of echo signal backscattered by a target and desensitization of radar detector by echoes in inaccuracy field of designation of distance and radial speed. The signal loss is generated by a loss due to remote eclipse produced by masking of one of the echoes received by the radar during duration of emitted pulse (Ei) and by another loss due to speed eclipse resulting from a difference between the speed and main clutter. The desensitization is caused by noise produced by the echoes backscattered by atmospheric clutter of noise.