基于瞬时相关频域检测的复合调制引信定距方法

为了实现混沌调相与线性调频复合调制无线电引信对不同散射特性的地面目标的精确定距功能，提出一种基于瞬时相关频域检测的复合调制引信定距方法。在时域瞬时相关处理之前，对本地预设混沌码与目标回波信号以码元宽度为采样周期进行同步采样；为减小目标回波幅值对定距方法的影响，以二维快速傅里叶变换（2D-FFT）提取目标的距离、速度信息，以相关窗位置、谐波包络主瓣位置、稳定的多普勒频率3个特征量作为定距依据，从频域角度进行精确定距。仿真结果表明:所提方法的判定结果只与目标信号信噪比有关，而与信号幅值具体大小无关；所提方法可在-28 dB的极低信噪比条件下实现复合调制引信对不同散射特性地面目标的精确定距功能。 

A ranging method of hybrid modulation fuze based on instant correlation frequency domain detection

For the radio fuze combining chaotic code bi-phase modulation with linear frequency modulation, a ranging method based on instant correlation frequency domain detection is proposed to achieve precise ranging for the ground targets with different scattering characteristics. Before instant correlation in time domain, the local chaotic code and the target echo signal are sampled synchronously with code width as sampling period; to reduce the influence of the target echo signal amplitude on ranging method, target distance and speed information are extracted by Two-Dimensional Fast Fourier Transform (2D-FFT), three feature quantities of the instant correlation window position, harmonic envelope main lobe position and stable Doppler frequency are used as the ranging basis, and precise ranging is achieved in frequency domain. Simulation results show that the judgement results of ranging method are only related to the signal-to-noise ratio of the target signal, regardless of the magnitude of the signal amplitude, and it can achieve precise ranging of the hybrid modulation radio fuze for the ground targets with different scattering characteristics in the circumstance of a very low signal-to-noise ratio -28 dB.