Research On Efficient Jamming Method In Communication Countermeasures

Communication jamming, as an important part of communication countermeasures, is an important means to win initiative on the battlefield. Therefore, in modern warfare, successful interference is an effective way against the enemy by degrading or even destructing the reliability of their communication link. With the continuous improvement of the military theory, and rapid developments of jamming technology, the requirements of communication jamming performance are increasingly demanding. This thesis study on the interference patterns and design the interference strategy to interfere the DSSS(direct spread spectrum system). The main contents of this thesis are shown as follows:1. Basing on theoretical analysis and simulation of the interference pattern, we propose a new interference strategy, it discontinuous interference strategy. Simulations are carried out with respect to the noise amplitude modulation jamming, linear frequency modulation jamming and Gaussian white noise jamming employing the proposed interference strategy to jam a spread spectrum system. The simulation results show that the interference strategy could provide better jamming performance compared with the conventional ones. Moreover, the impacts of bandwidth and center frequency of the noise on the jamming performance are studied, and the optimal parameters for intermittent interference are obtained;2. The performance of the discont jamming strategy to jam a communication system with AGC (automatic gain control) in the receiver are explored, with BPSK and BPSK-based spread spectrum system as a good system in simulations, respectively. Numerical results show that the appropriate choice of parameters for the discontinuous interference strategy could reduce the jamming-signal ratio at which the jamming appears to be effection. As for the BPSK-based spread spectrum system, the proposed interference strategy could also improve the jamming performance;3. The performance of the adaptive notch filter with the change of the carrier frequency of the jamming is investigated. Computer simulations show that, the converging speed of the adaptive notch filter rely not only on the radius of convergence, but also on the power of the jamming. When the frequency of jamming changes faster than the converging speed of the adaptive filter, it is hard for filter to converge, which means the efficiency of the designed jamming.