基于MIMO直达波的无人机分布式相参雷达相位同步方法

Phase synchronization method based on MIMO direct path wave for UAV distributed coherent aperture radar

分布式相参雷达(distributed coherent aperture radar,DCAR)实现信号全相参的前提是相位同步,而各单元雷达的初始时钟参差、机动性引入的位置误差、本地振荡器的初始相位等因素均会导致DCAR相位不同步问题。为解决上述相位不同步问题,提出一种基于多输入多输出(multiple input multiple output,MIMO)直达波的无人机DCAR相位同步方法。该方法对各单元雷达接收的直达波,首先利用包络同步法联合双向时间比对的方式,估计出时间同步误差,再提出坐标线性变换法和偏移线性变换法用于各单元雷达位置误差的估计,并联合同一单元雷达分置辅助天线接收波以提高位置误差的估计精度。最后,利用误差估计值对直达波进行补偿,剩余相位即不同单元雷达收发对下的初相估计。仿真实验验证了所提方法的有效性。

For the distributed coherent aperture radar(DCAR),the precondition to realize fully signal coherence is phase synchronization.The factors,such as initial clock jagging,position derivation owning to maneuverability and original phase of local oscillators(LOs)belonging to unit radars,mainly result in DCAR phase non-synchronization.Aiming to solve these problems,a phase synchronization method based on multiple input multiple output(MIMO)direct path wave for unmanned aerial vehicle(UAV)DCAR is proposed.Firstly,it estimates time synchronization derivation by means of envelope synchronization combining two-way time comparison.Then the coordinate linear conversion method and the offset linear conversion method are put forward,which combine different auxiliary antennas echoes owning to the same unit radars to improve the position deviation estimation accuracy.Finally,through compensation to the direct path wave using deviation estimation values,the rest phase reflects LOs original phase estimation belonging to different pairs.The numerical examples demonstrate the validity of the theoretical results.