Radar Anti-jamming Technology Research

Since the development of radar, radar jamming and anti-jamming measures have been fiercely competed. They become a much more important position in modern warfares. This thesis is focused on the study of anti-jamming algorithms. The main works are as follows: (1). Based on the theory of active suppression jamming, The character of noise amplitude modulation (NAM) and noise frequency modulation (NFM) are analyzed, The mathematic models are established and the impacts on radar receivers are researched. (2). Active suppression jamming is analyzed from the time and frequency domain. The characters almost without the influence of the noise are extracted. At the same time, the features quantificationally by modern signal processing are studied when Jamming-to-Noise Rate (JNR) varies in a certain range. Different feature extraction methods in different domains are used to explore the characteristics of active suppression jamming. (3) For NAM, the carrier frequency and initial phase of the jamming siginal are estimated, and then, the echo signal is demodulated with the estimated jamming carrier frequency, the jamming may be suppressed with frequency domain cancellation. For NFM, morlet wave transform and correlation processing are used which can effectively restrain the disturbance of NFM and system noise. Based on this, a simple technique of excising interference through envelope filtering is put forward. It is found by simulation that the technique applied in this paper can effectively excise the broadband interference, especially for strong interference. And the correlation output is improved obviously. At the same time, the performance of the above anti-jamming algorithm is estimatedThe results show the applied algorithm is effective for jamming resistance.