A Non-Uniformly Distributed Multi-Pulse Coded Waveform to Combat Azimuth Interrupted Sampling Repeater Jamming in SAR

Azimuth interrupted sampling repeater jamming (A-ISRJ) can produce several false targets with controllable position and quantity in azimuth on synthetic aperture radar (SAR) images because of the principle of under-sampling and the characteristic of azimuth matched filtering. A method based on multi-pulse coding with non-uniform distribution is proposed in this paper to counter A-ISRJ. The coding radar needs to transmit multiple sub-pulses at high and varying sub-pulse repetition frequency (SPRF) within the original pulse repetition interval (PRI). Then the corresponding decoding matrix is constructed according to the transmitted signal coding form to recover the complete target echo. The deceptively high SPRF of the coding signal will disturb the jammer to set the wrong A-ISRJ parameters and affect the expected jamming effect. And the intermittent sampling and uniform forwarding characteristics of A-ISRJ signal itself will cause it to mismatch with the decoding matrix determined by the non-uniformly distributed coding signal. This will result in the loss of the A-ISRJ energy. Simulation results with different jamming parameters and different types of A-ISRJ prove the availability of the coding method and show the low sensitivity of the coding method to jamming parameters.