高低轨双星时频模糊雷达信号的频差估计算法
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摘要
针对高低轨双星定位系统中,雷达信号定位参数估计结果同时存在时差与频差模糊的问题,分析了相参脉冲串信号的模糊特性;利用粗略配对的脉冲串获得到达时间差序列,避免了对时域高度密集的脉冲进行配对的难题;在此基础上,提出了对时差序列进行中心差分计算频差粗估值实现频差模糊消除的方法;推导得出了频差粗值误差随着辐射源载频的增加、脉冲到达时间测量误差的增大、时差差分间隔的减小而增大的结论。仿真结果表明,频差粗值误差与理论值一致;通过设置合理的差分间隔,得到无模糊的频差粗值以后,频差精估精度逼近CRLB。新算法便于工程实现,对长基线定位系统中雷达信号的频差估计具有一定参考价值。
In a GEO-LEO dual-satellite geolocation system,the estimations of the differential time offset( DTO) and differential frequency offset( DFO) are ambiguous at the same time. Aiming at this problem,the ambiguity of the coherent pulse trains signal is analyzed. And,the sequence of the differential time of arrival( TOA) is obtained by the roughly paired pulse trains to avoid the difficulty of the pulse match with high-density in the time domain. The coarse DFO whose ambiguity is eliminated is estimated by the central difference of DTO,and the performance of the coarse DFO estimation is derived. The result shows that the estimation error increases with the increasing of the carrier frequency of the emitter,the increasing of the error of the TOA and the decreasing of the time interval of the differential DTO. The numerical simulations have demonstrated that the coarse DFO estimation error is consistent with the theoretical value,and the estimation accuracy of the DFO approximates the Cramer-Rao lower bound( CRLB) when the coarse DFO estimation without ambiguity is obtained by setting the appropriate differential interval. The new approach is convenient for engineering implementation,and could provide good references for DFO estimation of the radar signal in a long base line location system.
In a GEO-LEO dual-satellite geolocation system,the estimations of the differential time offset( DTO) and differential frequency offset( DFO) are ambiguous at the same time. Aiming at this problem,the ambiguity of the coherent pulse trains signal is analyzed. And,the sequence of the differential time of arrival( TOA) is obtained by the roughly paired pulse trains to avoid the difficulty of the pulse match with high-density in the time domain. The coarse DFO whose ambiguity is eliminated is estimated by the central difference of DTO,and the performance of the coarse DFO estimation is derived. The result shows that the estimation error increases with the increasing of the carrier frequency of the emitter,the increasing of the error of the TOA and the decreasing of the time interval of the differential DTO. The numerical simulations have demonstrated that the coarse DFO estimation error is consistent with the theoretical value,and the estimation accuracy of the DFO approximates the Cramer-Rao lower bound( CRLB) when the coarse DFO estimation without ambiguity is obtained by setting the appropriate differential interval. The new approach is convenient for engineering implementation,and could provide good references for DFO estimation of the radar signal in a long base line location system.
引文
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[8]张宏元,穆贺强.基于相关算法消除高重频信号的时差定位模糊[J].系统工程与电子技术,2008,30(5):816-818.[Zhang Hong-yuan,Mu He-qiang. Eliminating TDOA location ambiguity about HPRF signal based on correlation algorithm[J].Systems Engineering and Electronics,2008,30(5):816-818.]
[9] Johnson J A,Fowler M L. Cramer-Rao lower bound on doppler frequency of coherent pulse trains[C]. 2008 IEEE International Conference on Acoustics,Speech and Signal Processing,Las Vegas,USA,March 31-April 4,2008.
[10]杨宇翔,夏畅雄,同武勤.高低轨双星定位中的时变时频差参数估计[J].信号处理,2012,28(10):1465-1474.[Yang Yu-xiang,Xia Chang-xiong,Tong Wu-qin. Estimation of the time varying TDOA and FDOA in GEO-LEO dual-satellites location system[J]. Signal Processing,2012,28(10):1465-1474.]
[11] Levanon N,Mozeson E. Radar Signals[M]. New Jersey:Wiley J&Sons Inc. Publication,2004.
[12]姚山峰,贺青,欧阳鑫信,等.一种低轨双星雷达信号无模糊频差估计算法[J].宇航学报,2018,39(11):1275-1283.[YAO Shan-feng,HE Qing,OUYANG Xin-xin,et al. A novel method for unambiguous DFO estimation of radar signals in LEO Dual-satellites geolocation system[J]. Journal of Astronautics,2018,39(11):1275-1283.]
[2]姜泉江,刘会杰.低轨卫星多波束接收的多普勒频移统计特性及应用[J].宇航学报,2014,35(6):720-725.[Jiang Quan-jiang, Liu Hui-jie. Statistical characteristics and application of doppler shift received by low earth orbit multi-beam satellite[J]. Journal of Astronautics,2014,35(6):720-725.]
[3] Scheuing J,Yang B. Disambiguation of TDOA estimation for multiple sources in reverberant environments[J]. IEEE Transactions on Audio, Speech, and Language Processing,2008,16(8):1479-1489.
[4] Li Z Q,Ge N,Huang Z,et al. A method to eliminate TDOA ambiguity based on FDOA and FDOA-rate[C]. 2015International Conference on Wireless Communications&Signal Processing,Nanjing,China,15-17 Oct,2015.
[5]李涛,姜文利,周一宇.高重频信号三星座时差定位研究[J].电子对抗技术,2004,19(41):7-11.[Li Tao,Jiang Wen-li,Zhou Yi-yu. TDOA location with high PRF signals based on three satellites[J]. Electronic Warfare Technology,2004,19(4):7-11.]
[6]钱剑勋.长基线时差定位中定位模糊问题[J].四川兵工学报,2010,31(5):138-140.[Qian Jian-xun. Location ambiguity in long-base-line TDOA location[J]. Journal of Sichuan Ordnance,2010,31(5):138-140.]
[7]任文娟,胡东辉,丁赤飚,等.利用测向信息消除高重复频率信号的时差定位模糊[J].电子与信息学报,2010,32(12):3003-3007.[Ren Wen-juan,Hu Dong-hui,Ding Chi-biao,et al. Eliminating TDOA location ambiguity of high PRF signal based on direction information acquired[J]. Journal of Electronics&Information Technology,2010,32(12):3003-3007.]
[8]张宏元,穆贺强.基于相关算法消除高重频信号的时差定位模糊[J].系统工程与电子技术,2008,30(5):816-818.[Zhang Hong-yuan,Mu He-qiang. Eliminating TDOA location ambiguity about HPRF signal based on correlation algorithm[J].Systems Engineering and Electronics,2008,30(5):816-818.]
[9] Johnson J A,Fowler M L. Cramer-Rao lower bound on doppler frequency of coherent pulse trains[C]. 2008 IEEE International Conference on Acoustics,Speech and Signal Processing,Las Vegas,USA,March 31-April 4,2008.
[10]杨宇翔,夏畅雄,同武勤.高低轨双星定位中的时变时频差参数估计[J].信号处理,2012,28(10):1465-1474.[Yang Yu-xiang,Xia Chang-xiong,Tong Wu-qin. Estimation of the time varying TDOA and FDOA in GEO-LEO dual-satellites location system[J]. Signal Processing,2012,28(10):1465-1474.]
[11] Levanon N,Mozeson E. Radar Signals[M]. New Jersey:Wiley J&Sons Inc. Publication,2004.
[12]姚山峰,贺青,欧阳鑫信,等.一种低轨双星雷达信号无模糊频差估计算法[J].宇航学报,2018,39(11):1275-1283.[YAO Shan-feng,HE Qing,OUYANG Xin-xin,et al. A novel method for unambiguous DFO estimation of radar signals in LEO Dual-satellites geolocation system[J]. Journal of Astronautics,2018,39(11):1275-1283.]