Technique to Counter Improved Active Echo Cancellation Based on ISRJ With Frequency Shifting

Interrupted-sampling repeater jamming (ISRJ) is an effective method to jam chirp radars. Furthermore, by modulating ISRJ repeater parameters, ISRJ achieves radar echo cancellation using the ISRJ false target that synchronizes with the true target echo, with the same amplitude and inverted phase. Recently, an improved method based on both ISRJ and frequency shifting modulation has been proposed to protect the true target more effectively in the presence of amplitude mismatch of cancellation signal and true target echo. In this paper, an anti-jamming technique based on waveform agility is proposed to counter this improved cancellation method. This technique not only eliminates the effect of the ISRJ echo canceler but also makes the true target power higher than that of the false ones. Therefore, it can be discriminated from the jamming ones easily. The theoretical analysis of this technique is presented, and its effectiveness is confirmed by MATLAB simulation.