| With the rapid development of modern technology, the pseudo random code continuous wave (PRC-CW) radar is facing all kinds of interference in applications, such as amplitude modulation interference, frequency modulation interference and AM-FM interference. Radar antijamming tolerance is certain. When the interference exceeds the tolerable limit, the correlation output deteriorates greatly. Therefore, interference suppression for radar is necessary before the correlation detection, making the target achieve normal detection.In recent years, the time-frequency analysis methods have got great development and a wide application, especially in the interference suppression. Therefore, it’s significant to research the interference suppression methods based on time-frequency analysis. In this paper, we mainly analyse two kinds of time-frequency transform methods, one is short time Fourier transform (STFT), the other is local polynomial Fourier transform (LPFT), and apply these two methods to FM interference suppression of PRC-CW radar.At first, this paper introduces the phase coded radar signal and all kinds of time-frequency analysis methods. The principle of interference suppression methods based on time-frequency analysis is briefly dicussed. Secondly, FM suppression based on the STFT and time-varying filtering is presented. Meanwhile, the performance comparison is simulated by MATLAB. Finally, a detailed discussion and simulation analysis of FM interference suppression method based on LPFT and time-varying filtering are presented. Moreover, using the LPFT estimates the instantaneous frequency of FM signals. These two methods are tested on the linear and sinusoidal FM types of interference suppression. When the signal-to-interference ratio (SIR) situations are-15dB,-20dB and-25dB, the simulation results demonstrate these two methods can restrain the interference effectively. And the interference suppression results of LPFT method are better than the STFT. |
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