Jamming Technique And Implementation For Countering PD Radar Based On DRFM

Pulse Doppler (PD) radar is one new type of radar, which is developed on Moving Target Indicator (MTI) radar. Using the techniques of coherent integration and frequency filtering, it can detect and track moving targets in strong clutter. Nowadays, the ECM of frequency shifting, along with range deceptive countering measures, is one of effective measures for jamming PD radars. In this way, the coherent jamming signal will have one or many deceptive doppler frequencies, which is useful for velocity deceptive jamming.Digital Radio Frequency Memory (DRFM) has become the core-controlling unit in many ECM systems, since it appeared more than 30 years ago. Its retransmitting signal reserves the coherent property of radar signal, and if doppler frequency shift is added, it can counter PD radars effectively.Based on the above context, the following contents are studied in this thesis:Firstly, the operational principle, the basic structures, the developmental history and future trend of DRFM are summarized, systematically. The ablity of coherent duplication of DRFM is studied specially.Secondly, jamming technique for countering PD radar based on DRFM are studied. The digital frequency-shifting circuit is designed, based on digital single sideband modulation (SSB), and is implemented, using FPGA. This circuit can be applied in DRFM systems for achieving precise frequency shift. The digital method for realizing range-velocity simultaneous pull-off is given, and the simulated results are outlined.Finally, to prove the circuit designed above, a DRFM module is designed, debuged and tested. The core-controlling unit is only one FPGA, which is used for storing the sampling datum and modulating the retransmitting signal.