Low-sidelobe nonlinear frequency modulation waveform optimization method based on Fourier series
A non-linear frequency modulation, Fourier series technology, applied in radio wave measurement systems, genetic models, genetic laws, etc., to achieve the effect of accelerating the reduction of side lobes
Active Publication Date: 2021-11-09
AEROSPACE INFORMATION RES INST CAS
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However, as iterations progress, it becomes increasingly difficult to find better performing NLFM waveforms through random search
Therefore, it is difficult to achieve fast convergence of the optimization process and the design of low sidelobe NLFM waveforms at the same time using the existing single optimization algorithm
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[0044] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without making creative efforts belong to the protection scope of the present invention.
[0045] According to an embodiment of the present invention, such as figure 2 As shown, a low sidelobe non-linear frequency modulation waveform optimization method based on Fourier series includes the following steps:
[0046] Step 1. Input NLFM waveform design based on Fourier series;
[0047] Step 2, combining the waveform diversity and the correction process in the improved genetic algorithm to carry out preliminary waveform design; using the i...
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The invention discloses a low-sidelobe nonlinear frequency modulation waveform optimization method based on Fourier series. According to the method, a two-step progressive optimization process is adopted and comprises an improved genetic algorithm and gradient-based tuning, so that rapid optimization of a low-sidelobe nonlinear frequency modulation waveform is realized. The method comprises the following steps: firstly, improving a genetic algorithm by combining the characteristics of a nonlinear frequency modulation waveform and waveform diversity so as to carry out controlled random search; the improved genetic algorithm is not only used for preliminary design of nonlinear frequency modulation waveforms, but also provides iteration points better than linear frequency modulation signals for gradient-based tuning. When the descent speed of the side lobe in the improved genetic algorithm is slowed down, gradient-based tuning is used to further adjust the waveform to obtain a lower side lobe without expanding the main lobe. When the normalized pulse response width of the optimized nonlinear frequency modulation waveform is 1.14, the peak sidelobe ratio of -45.3 dB and the integral sidelobe ratio of -29.0 dB are achieved.
Description
technical field [0001] The invention relates to the field of radar detection and imaging, in particular to a Fourier series-based low sidelobe nonlinear frequency modulation waveform optimization method. Background technique [0002] Among the various radar waveforms, low sidelobe radar waveforms are important because of their ability to detect faint targets. However, the most widely used chirp signal has a high sidelobe of -13.26dB after matched filtering. Reducing the sidelobe of a chirp signal by windowing results in a broadening of the main lobe and a decrease in SNR. In contrast, NLFM waveforms have an S-shaped frequency-time relationship that enables low sidelobes without loss of signal-to-noise ratio. Although the NLFM waveform is sensitive to Doppler frequency shift, this shortcoming can be ignored in some applications, such as synthetic aperture radar (Synthetic aperture radar, SAR) system. [0003] The traditional method of generating NLFM waveform is to use the...
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IPC IPC(8): G01S7/28G01S13/89G06N3/12G06F17/14
CPCG01S7/2813G01S13/89G06N3/126G06F17/14Y02D30/70
Inventor 李王哲谢沁余
Owner AEROSPACE INFORMATION RES INST CAS