Multi-Degree-of-Freedom FM Signal Optimization
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Solution Overview
Problem
Current radar systems using linear frequency modulation (LFM) signals face challenges in sidelobe suppression, leading to reduced signal-to-noise ratio (SNR) and loss of resolution due to the windowing process, which also widens the main lobe, necessitating the design of multi-degree-of-freedom FM signals that maintain SNR while minimizing main lobe widening.
Innovation Solution
A method and device utilizing an augmented Lagrangian genetic algorithm to optimize multi-degree-of-freedom FM signals by determining time domain functions, establishing constraint conditions and objective functions based on main lobe width and peak sidelobe ratio, and iteratively refining frequency control points to achieve optimal sidelobe suppression without significantly widening the main lobe.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If windowing process is performed on LFM signal for sidelobe suppression, then sidelobe level is reduced, but signal-to-noise ratio is reduced by 1 to 2 dB
Solution Approach 1:
The patent changes the signal parameters by using multi-degree-of-freedom FM signals with multiple frequency modulation rates instead of conventional LFM signals. By optimizing multiple frequency modulation rates (k1, k2, ..., kn) in the piecewise linear frequency function, the system achieves sidelobe suppression while maintaining signal energy and SNR, resolving the contradiction between sidelobe reduction and SNR preservation
Solution Approach 2:
The patent introduces dynamic frequency modulation by dividing the signal into multiple segments with different frequency modulation rates. The frequency function f(t) changes dynamically across different time intervals, allowing the system to adaptively control the spectral distribution to suppress sidelobes while maintaining main lobe integrity and signal energy
2Object-generated harmful factors
If windowing process is performed on LFM signal, then sidelobe suppression is achieved, but main lobe is widened and resolution is lost
Solution Approach 1:
The patent optimizes multiple frequency modulation rate parameters (k1, k2, ..., kn) to achieve the desired spectral characteristics. By carefully selecting these parameters, the system suppresses sidelobes while maintaining a narrow main lobe width, thereby preserving resolution without the need for conventional windowing that causes main lobe widening
Solution Approach 2:
The patent performs preliminary optimization of the frequency modulation parameters before signal transmission. By pre-calculating the optimal piecewise linear frequency function and its corresponding control points, the system prepares the signal with inherent sidelobe suppression characteristics, avoiding the need for post-processing windowing that would widen the main lobe and reduce resolution
3Object-generated harmful factors
If multi-degree-of-freedom FM signal is designed with multiple frequency modulation rates, then sidelobe suppression is improved, but signal design complexity increases
Solution Approach 1:
The patent segments the frequency modulation function into multiple linear segments, each with a constant frequency modulation rate. This segmentation approach (piecewise linear function) simplifies the design by breaking down the complex frequency control into manageable segments, where each segment's parameters can be independently optimized while collectively achieving sidelobe suppression
Solution Approach 2:
The patent replaces complex mechanical or empirical signal design methods with a mathematical optimization approach. By using optimization algorithms to automatically determine the optimal frequency modulation rates and control points, the system reduces design complexity while achieving superior sidelobe suppression compared to conventional methods
Data Source
AI summary
Provided are a method and device for designing and optimizing a multi-degree-of-freedom frequency-modulation (FM) signal, and a computer storage medium. The method includes that: a time domain function of the multi-degree-of-freedom FM signal is determined; the constraint condition and the objective function of multi-degree-of-freedom FM signal optimization are established; an algorithm model of augmented Lagrangian genetic algorithm is determined based on the constraint condition and the objective function; characteristic parameters of the first iteration of the algorithm model are initialized, where the characteristic parameters of the first iteration at least include the Lagrange multiplier of the first iteration and the offset of the first iteration; initialization signal of the multi-degree-of-freedom FM signal is acquired, and initialization frequency control points of the initialization signal are determined based on the initialization signal.