Research And Implementation Of Interference Technology Based On DRFM

In the field of electronic countermeasures,digital radio frequency memory(DRFM)technology is able to quickly store and reproduce radio-frequency signals and effectively interfere with advanced radar systems.Traditional GPS jamming methods use noise suppression or directly generate GPS signals on the basis of noise suppression for deception.These methods fail to utilize the information contained in real-time GPS signals and have defects such as low concealment,low efficiency,and high power requirements.In this paper,DRFM is considered to be employed in GPS jamming technology to overcome the aforementioned problems,which helps jammers quickly store real-time GPS signals and reproduce them.Based on the principles of DRFM and the theory of GPS,a GPS jamming scheme based on DRFM is proposed in this paper.According to the jamming scheme,a GNSSlike signal modulation jamming system and a radio frequency repeater deception jamming system are built on the USRP B210 + GNU Radio experimental platform,and the experimental scheme is designed to verify the jamming efficiency of the system.The main contributions in this paper are summarized as follows.1.The basic principles of DRFM and relevant theories of GPS are researched.The structure of DRFM implementation,C/A pseudo-random code and generation method of navigation message are mainly studied,and the overall GPS jamming scheme is proposed based on the principle of DRFM and the theory of GPS receiver.2.The GPS signal pattern is studied.A GNSS-like signal modulation jamming technology is proposed based on DRFM and verified by Matlab simulation.The simulation results show that the bit error rate caused by GNSS-like signal modulation jamming technology is 50% higher than that of repressive interference such as wideband Gaussian white noise at the same interference-to-signal ratio.3.The signal synchronization problem involved in radio frequency repeater deception jamming is researched,and the compensation methods for signal power,Doppler frequency shift,and code phase are proposed in the synchronization process to align the jamming signal parameters with the real signal parameters received by the target receiver.Finally,the simulation analyzes the influence of the interference signal on the target receiver tracking loop considering the synchronization error of the code phase and carrier frequency.4.GNU Radio software is utilized to complete the implementation of GPS jammer modules such as RF receiving and transmitting module,signal capturing and tracking module,and navigation message extraction module.According to the signal processing flow of the "receive-storage-processing-send" of DRFM,various software modules are called to construct the GNSS-like signal modulation jamming system and the radio frequency repeater deception jamming system.The software radio hardware,USRP B210,is used as the environment platform required for the interference experiment,and the experimental scheme is designed to verify these two jamming systems.Finally,the effectiveness of these two jamming systems is verified from the experimental results.