摘要
借助深入分析和长期积累,非合作定位系统可以获得关于电视、广播、导航等电磁信号波形的丰富先验信息,对这些信息加以利用有望大幅提高对信号参数的估计精度。该文针对导航、通信等欺骗干扰源及非法用户的无源定位需求,在观测站与辐射源之间存在相对运动的场景下,围绕已知波形信号开展时差频差估计问题研究。首先,通过引入已知的信号波形信息对观测站接收数据进行建模,直观呈现了观测数据与不同观测站信号相对于原始信号时延、频移的关系。随后,充分利用入射信号波形已知这一有利条件,通过估计两个观测站各自的时延和频移,并对不同观测站上的估计结果进行差分,提出了一种针对已知波形信号的双站时差、频差估计方法。在此基础上,该文分析了已知波形信号时频差估计精度的理论下界,揭示了时频差估计精度受观测站接收信号幅度等因素的影响情况,并进一步分析了双站时频差估计精度与单通道时延、频移估计精度之间的关系。最后,借助仿真实验验证了论文所提出的时频差估计方法在不同环境中的参数估计性能,以及信号波形先验信息的利用给时频差参数估计精度带来的提升情况。仿真结果表明,在所设定的信号环境中,该文所提出的方法对低信噪比的适应能力比基于互模糊函数的传统方法增强了15 dB左右;当该方法的参数估计性能达到收敛之后,其时差频差估计精度与CRLB非常吻合。
In-depth analysis and long-term accumulation can be used by non-cooperative positioning systems to obtain rich prior information about the waveforms of various electromagnetic signals such as those of television,radio,and navigation systems.The exploitation of this information is expected to significantly improve the signal-parameter estimation accuracy.This study focused on the time-difference-of-arrival(TDOA)problem and frequency-difference-of-arrival(FDOA)estimation of known waveform signals in the context of relative motion between the observation stations and emitter,aiming at providing a solution for the passive location problem of deception jamming for navigation and communication sources,as well as of illegal users.First,the data received at an observation station was modeled by introducing the known signal waveform information,and the relationships between the observed data and the time delays and frequency shifts of the signals of different observation stations relative to the original signal were visually presented.Then,taking full advantage of the known waveform of the incident signal,the TDOA and FDOA of two stations were effectively estimated by estimating the time delays and frequency shifts of the two stations,respectively,and then differentiating the estimates on different stations.On this basis,this study analyzed the theoretical lower bound of the estimation accuracy of the TDOA and FDOA parameters in this scenario,which revealed the influence of factors such as the received signal amplitude on the TDOA and FDOA estimation accuracies.The relationship between the estimation accuracies for the dual-station TDOA and FDOA values was also analyzed,along with the accuracies of the single-channel time delay and frequency shift estimates.Finally,the parameter estimation performances of the new method in different environments were verified using simulations.The simulation results showed that in the given signal environments,the adaptability of the new method to a low signal-to-noise ratio was approximately 15 dB higher than that of the traditional method based on the cross-ambiguity function;and when the parameter estimation performance of the new method reached convergence,its TDOA and FDOA estimation accuracies were very consistent with the theoretical lower bound given here.
作者
刘严
朱毅
张源
郭福成
LIU Yan;ZHU Yi;ZHANG Yuan;GUO Fucheng(College of Electronic Science and Technology,National University of Defense Technology,Changsha,Hunan 410073,China)
出处
《信号处理》
CSCD
北大核心
2024年第2期292-300,共9页
Journal of Signal Processing
基金
国家自然科学基金(61901494)。
关键词
时差频差估计
已知信号波形
运动观测站
互模糊函数
克拉美-罗界(CRLB)
time-difference-of-arrival(TDOA)and frequency-difference-of-arrival(FDOA)estimation
signals with known waveform
moving observers
cross-ambiguity function(CAF)
Cramer-Rao lower bound(CRLB)
