Sparse-based false target identification in pulse-Doppler radar with random pulse initial phase

For random pulse initial phase radar, the echo signal of false velocity target which is emitted by digital radio frequency memory (DRFM) repeat jammer always lags several pulse repetition interval (PRI) behind that of true target in terms of pulse initial phase. Consequently, the lag causes the difference in phase at the same PRI, and it provides the possibility of false target identification. Firstly, we propose to estimate the amount of lag based on minimum entropy of Doppler frequency spectrum. Based on the lag, a true-false target combined dictionary is then established. Due to the difference in initial phase, the signal of true and false targets can be represented sparsely under the combined dictionary. Simulation results indicate that the proposed method has high performance on detecting the true targets and high accuracy in evaluating the motion parameters of both true and false targets. Moreover, a conclusion is also made that the coherence matrix is circulant Toeplitz in the case that the phases are following random biphase form.