针对传统基于分数阶傅里叶变换(fractional Fourier transform,FRFT)的线性调频(linear frequency modulated,LFM)信号参数估计方法中估计精度和计算量难以同时满足实际要求的问题,提出一种分数域二分法的LFM信号参数估计方法。该方法...针对传统基于分数阶傅里叶变换(fractional Fourier transform,FRFT)的线性调频(linear frequency modulated,LFM)信号参数估计方法中估计精度和计算量难以同时满足实际要求的问题,提出一种分数域二分法的LFM信号参数估计方法。该方法分析量化了变换阶次误差对参数估计误差的影响,利用单分量LFM信号变换阶次和分数域展宽的关系,通过迭代不断缩小变换阶次的取值范围,获得满足初设阈值的最优阶次,并利用最优阶次和峰值位置对LFM信号进行参数估计。采用逐次重构消除的方法,可以对强弱混合的多分量LFM信号进行参数估计。仿真结果表明,在满足信噪比要求的条件下,该方法能够有效地对LFM信号进行参数估计,可以通过参数估计精度的要求选择不同阈值,与传统方法相比,在参数估计精度相当的情况下大大地减小了计算量。展开更多
在分布式星载雷达系统中,为了获得分集增益和高分辨性能,要求各雷达发射的波形具有较强的正交性和较低的多普勒敏感性.通过对双调频斜率(Double Frequency Slope,DFS)信号的自相关性、距离分辨率、互相关性以及多普勒容忍性等性能的研究...在分布式星载雷达系统中,为了获得分集增益和高分辨性能,要求各雷达发射的波形具有较强的正交性和较低的多普勒敏感性.通过对双调频斜率(Double Frequency Slope,DFS)信号的自相关性、距离分辨率、互相关性以及多普勒容忍性等性能的研究,推导出该波形各参数之间的关系.在此基础上,结合分布式星载雷达系统的要求提出了基于DFS信号的波形参数设计方法,并设计出具有正交性和低多普勒敏感性的DFS信号波形.研究结果表明:在信号时宽不变的情况下,增大各子信号间的调频斜率差可以提高多个DFS波形间的正交性;而要使DFS波形具有较低的多普勒敏感性,则可以通过增大信号带宽或减小调频斜率差来达到.仿真结果表明:利用波形参数间的相互关系设计出的DFS信号波形,能够较好地满足分布式星载雷达系统的要求.展开更多
An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the o...An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the output signal-to-interfer-ence-plus-noise ratio(SINR) sensitive to input interference-to-signal ratio(ISR) that results in an unstable synchronization,and the spectrum leakage serious in strong ISR situation.This approach firstly makes use of the windowed and lapped technique to the fractional Fourier transform(FRFT) to enhance the ISR improvement and lower the SNR loss.Then by weakening the interference and a secondary threshold process,interference energy can be suppressed as much as possible and the output SINR is less sensitive to the ISR.Finally,a joint fractional Fourier domain and time domain technique is proposed to overcome the residual interference energy caused by the strong interference or the discontinuous-phase interference.Theoretical analysis and simulation results show that the proposed algorithm can achieve better performance than the conventional methods in suppressing both the multi period LFM interference and the multi chirp-rate LFM interference,especially in the strong interference environment.展开更多
文摘针对传统基于分数阶傅里叶变换(fractional Fourier transform,FRFT)的线性调频(linear frequency modulated,LFM)信号参数估计方法中估计精度和计算量难以同时满足实际要求的问题,提出一种分数域二分法的LFM信号参数估计方法。该方法分析量化了变换阶次误差对参数估计误差的影响,利用单分量LFM信号变换阶次和分数域展宽的关系,通过迭代不断缩小变换阶次的取值范围,获得满足初设阈值的最优阶次,并利用最优阶次和峰值位置对LFM信号进行参数估计。采用逐次重构消除的方法,可以对强弱混合的多分量LFM信号进行参数估计。仿真结果表明,在满足信噪比要求的条件下,该方法能够有效地对LFM信号进行参数估计,可以通过参数估计精度的要求选择不同阈值,与传统方法相比,在参数估计精度相当的情况下大大地减小了计算量。
文摘在分布式星载雷达系统中,为了获得分集增益和高分辨性能,要求各雷达发射的波形具有较强的正交性和较低的多普勒敏感性.通过对双调频斜率(Double Frequency Slope,DFS)信号的自相关性、距离分辨率、互相关性以及多普勒容忍性等性能的研究,推导出该波形各参数之间的关系.在此基础上,结合分布式星载雷达系统的要求提出了基于DFS信号的波形参数设计方法,并设计出具有正交性和低多普勒敏感性的DFS信号波形.研究结果表明:在信号时宽不变的情况下,增大各子信号间的调频斜率差可以提高多个DFS波形间的正交性;而要使DFS波形具有较低的多普勒敏感性,则可以通过增大信号带宽或减小调频斜率差来达到.仿真结果表明:利用波形参数间的相互关系设计出的DFS信号波形,能够较好地满足分布式星载雷达系统的要求.
基金partially supported by the National Natural Science Foun-dation of China for Distinguished Young Scholars (Grant No. 60625104) the Foundation for Beijing Excellent Ph.D,Thesis (Grant No. 1320037010901)
文摘An interference suppression algorithm is proposed to meet challenges of the traditional technique in dealing with the linear frequency modulation(LFM) interference,such as high loss of signal-to-noise ratio(SNR),the output signal-to-interfer-ence-plus-noise ratio(SINR) sensitive to input interference-to-signal ratio(ISR) that results in an unstable synchronization,and the spectrum leakage serious in strong ISR situation.This approach firstly makes use of the windowed and lapped technique to the fractional Fourier transform(FRFT) to enhance the ISR improvement and lower the SNR loss.Then by weakening the interference and a secondary threshold process,interference energy can be suppressed as much as possible and the output SINR is less sensitive to the ISR.Finally,a joint fractional Fourier domain and time domain technique is proposed to overcome the residual interference energy caused by the strong interference or the discontinuous-phase interference.Theoretical analysis and simulation results show that the proposed algorithm can achieve better performance than the conventional methods in suppressing both the multi period LFM interference and the multi chirp-rate LFM interference,especially in the strong interference environment.
