基于DMTD多普勒补偿的互补码脉冲压缩

Implementation of Complementary Codes Pulse Compression Based on DMTD for Compensating Doppler Drift

为解决相位编码脉冲压缩信号的旁瓣导致大目标信号的旁瓣覆盖小目标,降低雷达对小目标的检测能力,提出一种基于数字动目标检测(DMTD)的交替发射互补码的方法,对正码和补码回波分别做MTD,然后分两步进行相位补偿,并分别脉压和叠加(去旁瓣).该方法能有效地补偿多普勒频移和分时发射导致的相位差,保持了脉压后正码和补码回波信号旁瓣的互补性.由于是交替发射正码和补码,能有效降低目标RCS的角闪烁导致的回波能量起伏带来的影响.以四相互补码为例进行了仿真,结果表明,该方法补偿了由于分时发射造成的互补码之间的初始相位差,脉冲压缩后对互补码进行叠加,得到了低旁瓣的脉冲压缩结果.

The range sidelobe of phase-coded compression signals could induce the problem that the sidelobe of a large target might mask the presence of nearby smaller target, which reduce the ability of radar to detect the small target. Complementary codes in theory can solute this problem well, but, in practice, complementary codes have Doppler sensitivity problem： as the increase of Doppler frequency drift, complementarity of range sidelobe between the pair of complementary codes would reduce rapidly, which leads to the rise of sidelobe. To attack the problem above, a method of alternative transmit the complementary codes based on Digital Moving Target Detect （DMTD） is presented in this research. In processing, firstly, it should separately do MTD to positive code echo matrix and complementary code echo matrix. Then the phase difference would be compensated. At last, the pulse compression and superposition would be carried out to remove sidelobe. The presented method can effectively compensate the Doppler frequency shift and phase difference between the pair of complementary codes due to time division transmission, and maintain the complementarity of range sidelobe between the positive and complementary code echo. In addition, alternative emission of complementary codes could decrease the influence of echo energy fluctuation induced by angular glint.