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Nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility

A technology of non-linear frequency modulation and linear frequency modulation signals, which is applied in radio wave measurement systems and instruments, etc., can solve problems affecting target detection, distance ambiguity, clutter folding, etc., achieve low cross-correlation, reduce the degree of mismatch, and achieve equivalent Bandwidth same effect

Pending Publication Date: 2021-05-04
BEIJING INSTITUTE OF TECHNOLOGYGY
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Problems solved by technology

Due to the RSM effect, when the signal is processed by Doppler, the energy will diverge in the velocity dimension and cannot be suppressed by the traditional windowing method, thus affecting the detection of the target
[0004] Aiming at the problem of weak target detection under strong clutter conditions, there are defects of range ambiguity and clutter folding

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  • Nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility
  • Nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility
  • Nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility

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Embodiment Construction

[0031] The present invention will be described in detail below with reference to the accompanying drawings and examples.

[0032] According to the definition of the cross-correlation function, the value of the two waveform cross-correlation functions is mainly related to the similarity of the waveform in the time domain or frequency domain. Therefore, the less two waveforms with the same energy overlap in the time or frequency domain, the lower the cross-correlation, and vice versa. The present invention has found through research that based on the spectrum structure of the linear frequency modulation signal, random sinusoidal modulation is performed on the signal spectrum to generate waveform diversity, which can make the waveform have high flexibility and good cross-correlation characteristics, thereby suppressing clutter folding and interference At the same time, it also makes the equivalent bandwidth of the waveform spectrum the same, reduces the signal-to-noise ratio loss...

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Abstract

The invention discloses a nonlinear frequency modulation pulse train waveform design method based on frequency spectrum modulation agility, which can generate different NLFM waveforms by using a stationary phase principle based on a frequency spectrum structure of an LFM signal, and can effectively suppress the problems of range ambiguity, interference and clutter folding. The method comprises the following steps: determining a pulse width T, a bandwidth B, a pulse repetition interval Tr and a pulse number N of a waveform to be designed, generating linear frequency modulation signals with the same bandwidth and pulse width, and obtaining a power spectral density function L(f) of the linear frequency modulation signals; reserving the out-of-band shape of the L(f), modulating the amplitude of the in-band power spectral density function of the L(f) through a random sinusoidal modulation method, and designing an NLFM waveform power spectral density function NL (f); calculating a group delay function Tg(f) of the NLFM signal based on the NL(f); and determining the instantaneous frequency f(t) of the signal according to the group delay function Tg(f): conducting integration on the instantaneous frequency f(t) to obtain a phase function of the signal, and obtaining a time domain expression of the designed NLFM waveform according to the phase function.

Description

technical field [0001] The invention relates to the technical field of radar waveform design, in particular to a nonlinear frequency modulation burst waveform design method based on spectrum modulation agility. Background technique [0002] Pulse agility radar is a waveform diversity system that realizes waveform agility by transmitting radar waveforms with different carrier frequencies or different modulations between pulses or pulse groups within a coherent processing interval (CPI). The agile waveform can effectively suppress range ambiguity and clutter folding, which is beneficial to improve the target detection performance of the radar system in the background of clutter and interference. [0003] The linear frequency modulation (Linear Frequency Modulation, LFM) signal is simple in form, easy to generate, and has a large Doppler tolerance, so it is the most widely used pulse compression waveform. At the same time, the instantaneous frequency of the LFM signal changes ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01S7/282G01S7/28
CPCG01S7/282G01S7/2813
Inventor 任丽香庄若丹沙明辉毛二可范花玉
Owner BEIJING INSTITUTE OF TECHNOLOGYGY
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