Systems Engineering and Electronics ›› 2024, Vol. 46 ›› Issue (10): 3334-3346.doi: 10.12305/j.issn.1001-506X.2024.10.11

• Sensors and Signal Processing • Previous Articles    

Radar signal modulation recognition method based on synchro-extracting transform denoising

Zhian DENG1,2, Zhiguo WANG1,2, Sheng'ao WANG3,*, Weijian SI1,2   

  1. 1. College of Information and Communication Engineering, Harbin Engineering University, Harbin 150001, China
    2. Key Laboratory of Advanced Marine Communication and Information Technology, Ministry of Industry and Information Technology, Harbin 150001, China
    3. Department of Science and Information Technology, Sichuan Jiuzhou Investment Holding Group Company Limited, Mianyang 621000, China
  • Received:2023-06-10 Online:2024-09-25 Published:2024-10-22
  • Contact: Sheng'ao WANG

Abstract:

Due to the insufficient time-frequency focusing ability of the existing Cohen-class time-frequency distribution and low modulation recognition accuracy under low signal to noise ratio (SNR), a grouped convolutional neural network modulation recognition method based on synchronous extracting transform (SET) denoising is proposed. Firstly, SET is used for time-frequency analysis of the radar signals, providing better time-frequency focusing and computational efficiency of time-frequency analysis. Then, the Viterbi algorithm is utilized to search and estimate the instaneous frequency trajectory in the time-frequency coefficient matrix, taking into account the distribution of signal energy intensity and the smoothness of the instaneous frequency trajectory. At the same time, a median filter is applied to remove pulse noise from the obtained instaneous frequency trajectory, and the time-frequency coefficients in the vicinity of the instaneous frequency trajectory are retained to achieve time-frequency image denoising. Finally, the denoised time-frequency images are sent to a grouped convolution neural network with residual connections for feature extraction and modulation recognition. The experimental results demonstrate that, when the SNR is -12 dB, the denoised SET time-frequency images have good time-frequency focusing, and the modulation recognition accuracy is improved by 13.69% compared to the recognition accuracy without denoising. The proposed radar signal modulation recognition method exhibits excellent recognition performance for various complex modulation types of signals under low SNR conditions.

Key words: radar signal modulation recognition, synchro-extracting transform, instaneous frequency estimation, denoising

CLC Number: 

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