Noise amplitude modulation jamming suppression method based on time domain cancellation

Abstract

The invention discloses a noise amplitude modulation jamming suppression method based on time domain cancellation, belongs to the technical field of radar anti-jamming, and especially relates to parameter estimation, fast Fourier transform and search traversal technologies. Logarithm transformation is carried out on a receiving signal; jamming amplitude information is extracted from a real part; a noise amplitude modulation jamming signal is divided by the amplitude, thereby forming a single frequency signal of which frequency is jamming carrier frequency and phase is jamming initial phase; and Fourier transform is carried out on the signal, thereby obtaining the jamming carrier frequency and the jamming initial phase. In order to increase estimation precision, zero padding is carried out on the Fourier transform. The processing effectiveness is showed by simulation. According to the algorithm, a practical sampling rate is unnecessarily increased, there is no special demand for the relationship between the jamming carrier frequency and signal carrier frequency, and the method has general applicability.

Description

technical field [0001] The invention belongs to the technical field of radar anti-jamming, and particularly relates to parameter estimation, fast Fourier transform and search traversal technology. Background technique [0002] In electronic warfare, suppression jamming is easy to generate, has variable bandwidth, obvious suppression effect, and can simultaneously interfere with frequency diversity radars, frequency agility radars, and radars of various operating frequencies without predicting the radar emission waveform in advance. Therefore, it has been widely used in radar countermeasures. Among them, noise amplitude modulation jamming is an important way to achieve suppressive jamming, and it is widely used in targeted or compound jamming of radars. When the interference power exceeds the radar signal by tens of decibels, the target echo signal is completely covered by the interference signal, so that the target cannot be detected, and it is impossible to complete the tr...

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Problems solved by technology

However, there are defects in the above method. First, the signal carrier frequency and the interference carrier frequency must not be equal, and the difference between the two must make the signal part completely located on the positive or negative half axis of the frequency domain. For example, assuming that the signal The carrier frequency is greater than the interference carrier frequency, and the bandwidth of the chirp signal is B. After demodulation, the difference between the signal carrier frequency and the interference carrier frequency should be greater than half of the signal bandwidth. figure 1 As shown, that is to say, the signal is completely moved to the negative half axis of the frequency domain

Second, because in the literature, when solving the frequency of the periodic triangular wave, Fourier transform is performed on it, and the frequency is estimated by using the characteristics of its spectrum. However, the premise of obtaining a more perfect triangular wave spectrum is to fully sample it, and From the relationship between the frequency of the periodic triangular wave and the carrier frequency, it can be seen that the larger the carrier frequency is, the larger the sampling frequency is required. For radar signal processing, the sampling rate and the carrier frequency are irrelevant. When the carrier frequency is larger and the sampling rate is lower Hours, the noise amplitude modulation suppression method based on frequency domain cancellation will lose its effect

However, this algorithm has high computational complexity and loses its effect when the interference is strong

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