摘要
无源定位能够在隐蔽的状态下连续工作,是重要的侦察手段。针对DS-SS通信信号,本文提出一套无源定位理论方案。方案从估计DS-SS信号到达时间差(TDOA)入手,设计了相关法估计TDOA的快速算法,借助FFT能够把运算量减小到直接进行相关运算的很小一部分。接着就相关法面临的问题,导出频域交织子空间法,着力解决了直接使用常规的子空间法估计TDOA时低输入信噪(干)比、有限带宽和信道频率响应估计的有偏性三个问题。该方法能够识别小于一个码片时延的多径信号,对各路信号的TDOA予以超分辨率的估计,使TDOA测量精度满足战术定位要求。由于使用了无源匹配滤波器进行接收,对干扰也有很好的抑制作用。在介绍TDOA测量技术之后,还探讨了对敌未知码结构DS-SS信号TDOA测量方法,尝试对LPI信号源侦察定位。最后在高精度,超分辨率TDOA测量的基础上进行目标坐标估算,力求达到最小方差定位。条件允许的情况下增加一个主站信号到达角测量值进行定位,由于信号到达角测量技术已经非常成熟,本文不对AOA测量作过多的探讨。综合利用TDOA和仅有的一个AOA测量值,提出了一种近似最优的TDOA-AOA-2LS定位算法,以闭合解的形式给出了目标的最小方差定位结果。与仅用TDOA测量结果的TDOA-2LS方法相比,TDOA-AOA-2LS第二次近似带来的误差完全可以忽略,因而在能够在更大的范围内逼近克拉美-罗界,保持最优估计性能。仿真结果表明,在通信(话音)可以容忍的干扰和噪声环境中,方案可以对100km距离上的目标提供GDOP小于300m的定位,满足作战和训练的需求,为DS-SS信号源战术定位提供了理论依据。
Passive location, which can work silently for quite long time, is an important reconnaissance strategy. This paper provides a scenario aiming at location of a DS-SS communication signal emitter. Starting with estimating TDOAs of the DS-SS signals, the scenario projects first a fast correlation method that can reduce the amount of calculation to a small fraction of original amount by means of FFT. However, the cross correlation method suffers a lot from the small delay multi-paths and jamming. Frequency domain subspace method with interleaving can solve these two problems. This algorithm exerts extensive efforts to solve three problems, the low input SNR, limited frequency samples and biased estimation of the channel frequency response in normal subspace TDOA methods, distinguishing multi-path signals with arrival difference less than 1 chip time from each other, acquiring high precision and super resolution TDOAs. Receiving the signals by passive match filter can suppress most jamming. Following the TDOA estimating methods provided is interception of the DS-SS code in noisy and interferential background, in order to utilize the super resolution method to estimate the TDOAs of unknown DS-SS signals. Based on the high precession, super resolution estimate of TDOAs, the target is located with the least square error. An AOA value is added to the TDOAs when it is convenient to get the AOA information in the main base. As the AOA estimation belongs to another task, no more discussion provides here. Colligating the TDOAs and the only one AOA, TDOA-AOA-2LS, a method that can get optimum results is provided. Compared with twice in TDOA-2LS utilizing only the TDOA information, this method approximates only once, so as to keep location errors’rms achieving the Cramer-Rho bound with larger TDOA errors tolerance. The simulation indicates that this scenario satisfies tactic location, supplying theoretic foundation for location of DS-SS signal emitter.
引文
[1] Marvin K.Simon, Jim K.Omura, Robert A.Scholta, etc..Spread Spectrum Communications Handbook.北京:人民邮电出版社, 2002:405~833P
[2]张正明.辐射源无源定位研究.西安:西安电子科技大学,2000
[3]贾玉贵.现代对空情报雷达.北京:国防工业出版社,2004:80~94页
[4]单月晖.空中观测平台对海面慢速目标单站无源定位跟踪及其关键技术研究.长沙:国防科学技术大学,2002
[5]孙仲康,周一宇,何黎星.单多基地有源无源定位技术.北京:国防工业出版社,1996:181~214页
[6] Knapp Charls H, Clifford Carter.The Generalized Correlation Method for Estimation of Time Delay.IEEE Trans.On Acoust.Speech, Signal Processing, 1976, 24(4):320~326P
[7] Jingdong Chen, Jacob Benesty, Yiteng (Arden) Huang.Performance of GCC and AMDF-Based Time-Delay Estimation in Practical Reverberant Environments.EURASIP Journal on Applied Signal Processing, 2005, (1): 25~36P
[8] Xinrong Li, Kaveh Pahlavan.Super-Resolution TOA Estimation with Diversity for Indoor Geolocation.IEEE Trans.Wireless Comm.2004, 3(1):224~234P
[9] Marie-Agnès Pallas, Geneviève Jourdain.Active High Resolution Time Delay Estimation for Large BT Signals.IEEE Trans.SP, 1991, 39(4):781~787P
[10] H.Saarnisaari.TLS-ESPRIT in a time delay estimation.IEEE 47th VTC.Phoenix, USA, 1997:1619-1623P
[11]胡广书.数字信号处理-理论算法与实现.北京:清华大学出版社, 2003:169~216页
[12]毛用才,胡奇英.随机过程.西安:西安电子科技大学出版社,1998:70~98页
[13]赵树杰.信号检测与估计理论.西安:西安电子科技大学出版社, 1998:223~240页
[14]王永良,陈辉等.空间谱估计理论与算法.北京:清华大学出版社,2004:41~139页
[15]吴继礼,苟彦新,李琴.一种直扩盲截获方法初探.通信对抗,2005年第03期:27~29页
[16]吴继礼,苟彦新.干扰和噪声环境中直扩信号的截获.电讯技术,2006年第04期:119~122页
[17]王剑,贾坤,朱银川等.直扩信号检测与估计的改进.电讯技术,2004,44(1):44~47页
[18]孟建,胡来招.直扩信号检测的相关积累技术.电子对抗技术,2001,16(2):1~5页
[19]王铭三等.通信对抗原理.北京:解放军出版社,1999:160~173页
[20] French C A, Gardener W A.Spread-spectrum dispreading without the code.IEEE Trans Comm.1986, 34(4):404~407P
[21]余敬东,郭伟,李牧.直接序列扩频通信的循环谱检测和参数估计技术.电子科技大学学报,1996,25(9):439~444页
[22]张天骐,林孝康,周正中.低信噪比直扩信号扩频码的盲估计方法.清华大学学报,2005.45(1):48~51页
[23]冯富强,陈鹏举等.低信噪比条件下DS信号的检测和参数估计.通信学报,2002,23(9):63~68页
[24]王剑,贾坤,朱银川.直扩信号检测与估计的改进.电讯技术.2004(1):44~47页
[25]张贤达,保铮.非平稳信号处理.北京:国防工业出版社,2001:324~355
[26]苟彦新,王永民,郭建新等.无线电抗干扰通信原理及应用.西安:西安电子科技大学出版社,2005:53~64页
[27] W.H.Foy.Position-location solutions by Taylor-series estimation.IEEE Trans.Aerosp.Electron.Syst.1976, 12(2):187~194P
[28] J.o.Smith, J.S.Abel.Closed-form least-squares source location estimation from range-difference measurements.IEEE Trans.Acoustic.Speech, SignalProcessing, 1987, 35(12):1661~1669P
[29] Y.T.Chan, K.C.Ho.A Simple and Efficient Estimator for Hyperbolic Location.IEEE Trans.Signal Proc, 1994, 42(8):1905~1915P
[30] Petre stoica, Arye Nehorai, MUSIC, Maximun Liklihood, and Cramer-Rao Bound.IEEE Transactions on Acoustics Speech and Signal Processing, 1989, 37(5):720~741P
[31] Petre stoica, Arye Nehorai.MUSIC, Maximun Liklihood and Cramer-Rao Bound:Futher Results and Comparisons.IEEE Transactions on Acoustics Speech and Signal Processing, 1990, 38(12):720~741P
[32] D.J.Tonieri.Statistical theory of passive location systems.IEEE Trans.on AES.1984, 20(2):183~198P
[33] Yang B.Scheuing, J.Cramer-Rao bound and optimum sensor array for source localization from time differences of arrival.IEEE.CASSP '05.Philadelphia, 2005:IV-961~964P