短相干处理时间情况下的机动目标检测与参数估计

发布时间：2018-06-13 02:32

本文选题：机动目标 + 参数估计　；参考：《中国民航大学》2015年硕士论文

【摘要】：机动目标回波信号的多普勒频率在相干处理时间(Coherent Processing Interval,CPI)内随时间发生变化,即发生多普勒走动,使得传统的空时自适应处理(Space-Time Adaptive Processing,STAP)算法相参积累性能降低,导致机动目标检测与参数估计能力下降。当机动目标的加速度恒定时,其回波信号可视为线性调频(Linear Frequency Modulation,LFM)信号。而采用时频分析方法对加速度恒定的机动目标进行检测和参数估计时需要的脉冲数较多,否则参数估计精度难以满足要求。机载雷达在一个CPI内发射的脉冲数相对较少,当脉冲重复频率一定时,脉冲数较少意味着相干处理时间变短。因此,很难将时频分析方法直接应用到短相干处理时间情况下机载雷达的机动目标检测与参数估计的研究中。针对上述问题,本论文提出的机动目标检测与参数估计方法在短相干处理时间情况下能够获得较高的参数估计精度。论文的主要贡献和创新之处主要有:第一,介绍了机载雷达接收的回波数据模型,通过对多普勒问题的描述推导出机动目标的回波数据模型;第二,提出了一种基于重构信号和时间采样的机动目标检测与参数估计方法,该方法在短相干处理时间情况下仍然可以获得较好的机动目标参数估计结果,参数估计性能更加接近Cramer-Rao下界。第三,提出了一种基于压缩感知和三次相位变换(Cubic Phase Transform,CPT)的低复杂度机动目标参数估计方法,可用小于Nyquist采样定理要求的采样频率对信号进行采样和压缩。在短相干处理时间情况下,该方法不仅能够获得准确的机动目标参数估计结果,而且运算复杂度较低。第四,推导出机动目标参数估计的Cramer-Rao下界,为验证本论文提出算法的有效性提供了理论依据。
[Abstract]:The Doppler frequency of maneuvering target echo signal changes with time in coherent processing time and coherent processing (CPI), that is, Doppler migration occurs, which makes the coherent accumulation performance of traditional space-time adaptive processing Space-Time Adaptive processing STAP algorithm decrease. The ability of maneuvering target detection and parameter estimation is reduced. When the acceleration of maneuvering target is constant, the echo signal can be regarded as linear frequency modulation LFM signal. The time-frequency analysis method is used to detect and estimate the parameters of maneuvering targets with constant acceleration. Otherwise, the precision of parameter estimation is difficult to meet the requirements. The number of pulses transmitted by airborne radar in a CPI is relatively small. When the pulse repetition rate is fixed, the less pulse number means the shorter coherent processing time. Therefore, it is difficult to apply the time-frequency analysis method directly to the research of maneuvering target detection and parameter estimation of airborne radar under the condition of short coherent processing time. In order to solve the above problems, the method of maneuvering target detection and parameter estimation proposed in this paper can obtain high precision of parameter estimation under the condition of short coherent processing time. The main contributions and innovations of this paper are as follows: firstly, the echo data model of airborne radar is introduced, and the echo data model of maneuvering target is deduced by describing the Doppler problem. A maneuvering target detection and parameter estimation method based on reconstructed signal and time sampling is proposed. The method can still obtain better estimation results of maneuvering target parameters under the condition of short coherent processing time. The parameter estimation performance is closer to the Cramer-Rao lower bound. Thirdly, a low complexity maneuvering target parameter estimation method based on compressed sensing and cubic phase transform (CPT) is proposed, which can sample and compress the signal at a frequency less than the sampling frequency required by Nyquist sampling theorem. In the case of short coherent processing time, this method can not only obtain accurate estimation results of maneuvering target parameters, but also lower computational complexity. Fourthly, the Cramer-Rao lower bound for the estimation of maneuvering target parameters is derived, which provides a theoretical basis for verifying the validity of the proposed algorithm in this paper.
【学位授予单位】：中国民航大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN957.51

【参考文献】