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Modulation Type Recognition of Radar PRI Based on Multi-feature Combination
Junchen LIU, Bo YAN, Chunlei ZHAO, Wenzhong ZHOU
Modern Defense Technology    2025, 53 (1): 129-139.   DOI: 10.3969/j.issn.1009-086x.2025.01.014
Abstract53)   HTML2)    PDF (2284KB)(89)       Save

A multi-feature joint method for radar pulse repetition interval (PRI) modulation type recognition is proposed to address the challenges of low recognition accuracy, significant impacts from pulse loss and false pulses, and sensitivity to decision threshold settings in existing types. First, the concept of density clustering is employed to remove irrelevant pulses, enabling the preprocessing of the pulse train and mitigating the effects of pulse loss and spurious pulses on pulse train patterns. Statistical methods are then applied to extract the stability features, second-order differential variation features, continuity features and pulse pair matching features of signal time difference. Finally, a random forest algorithm is used to train and test the extracted features. The simulation results demonstrate that the proposed method achieves high recognition accuracy for PRI modulation types and exhibits robust resistance to pulse loss and spurious pulses.

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Frequency Shift Interference Suppression Method Based on Frequency Estimation and Signal Reconstruction
Shan-shan JIN, Xin LI, Chen LIU
Modern Defense Technology    2022, 50 (6): 97-102.   DOI: 10.3969/j.issn.1009-086x.2022.06.012
Abstract4385)   HTML217)    PDF (928KB)(467)       Save

Frequency shift interference can produce high fidelity false targets for the range-Doppler coupling characteristic of LFM signal. According to the peak characteristics of pulse echo by compression and the principle of dechirp, the interference suppression method based on signal reconstruction and cancellation is proposed. Firstly, the frequency of the signal by dechirp is estimated, and the dechirp interference signal is reconstructed. Secondly, the normalized average detection threshold is defined for the dechirp signal, and the minimum threshold is used as the objective function of interference suppression. Finally, the interference suppression factors corresponding to the minimum normalized average monitoring threshold are calculated by global search, and interference suppression is realized by cancellation. The simulation shows that the energy of residual interference component is more than 20 dB lower than that of target echo in the output signals by pulse compression, which shows the proposed method can suppress multi-frequency shift interference effectively.

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