一种改善GNSS弱信号动态跟踪性能的FFT鉴频方法
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摘要
基于快速傅里叶变换(FFT)鉴频器的GNSS弱信号跟踪技术可以有效改善城市峡谷环境的行人导航,然而现有的复数平方FFT(SFFT)鉴频器在车载等较高动态应用中弱信号跟踪性能大幅度下降。本文提出了一种在保证弱信号跟踪灵敏度的前提下,能显著提高动态性能的FFT鉴频方法——非相干FFT鉴频器(NonCoh-FFT)。首先,介绍了SFFT鉴频器和NonCoh-FFT鉴频器的结构原理;然后,从理论上分析了两者的灵敏度和动态性能;最后,基于GNSS信号模拟器产生的静态和动态场景,对比测试验证了SFFT和NonCoh-FFT性能。结果表明,NonCoh-FFT可以明显提高GNSS弱信号动态性能,与理论分析吻合。
The GNSS weak signal tracking technology based on the FFT frequency discriminator can effectively improve pedestrian navigation in urban canyon environment;however,the weak signal tracking ability of existing Complex Squared FFT(SFFT)discriminators would be greatly reduced in vehicles and other high dynamic applications.On the premise of ensuring the sensitivity of weak signal tracking,a Non-Coherent FFT(NonCoh-FFT)frequency discrimination is proposed,which can significantly improve dynamic performance.First,the structure principle of the existing SFFT frequency discriminator and the proposed NonCoh-FFT frequency discriminator are analyzed.Then,the sensitivity and dynamic performance of the two discriminators are analyzed theoretically.Finally,based on the static and dynamic scenes of the GNSS signal simulator,the SFFT and NonCoh-FFT are compared and tested.The results show that the NonCoh-FFT can obviously improve the dynamic performance of the GNSS weak signal,which is consistent with the conclusion of theoretical analysis.
The GNSS weak signal tracking technology based on the FFT frequency discriminator can effectively improve pedestrian navigation in urban canyon environment;however,the weak signal tracking ability of existing Complex Squared FFT(SFFT)discriminators would be greatly reduced in vehicles and other high dynamic applications.On the premise of ensuring the sensitivity of weak signal tracking,a Non-Coherent FFT(NonCoh-FFT)frequency discrimination is proposed,which can significantly improve dynamic performance.First,the structure principle of the existing SFFT frequency discriminator and the proposed NonCoh-FFT frequency discriminator are analyzed.Then,the sensitivity and dynamic performance of the two discriminators are analyzed theoretically.Finally,based on the static and dynamic scenes of the GNSS signal simulator,the SFFT and NonCoh-FFT are compared and tested.The results show that the NonCoh-FFT can obviously improve the dynamic performance of the GNSS weak signal,which is consistent with the conclusion of theoretical analysis.
引文
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[16]富立,王淼,王玲玲.高动态GPS载波锁相环切换稳定性分析[J].航空学报,2013,34(11):2572-2579.FU L,WANG M,WANG L L.Stability analysis of high dynamic GPS carrier phase-locked loop via switching system[J].Acta Aeronautica et Astronautica Sinica,2013,34(11):2572-2579(in Chinese).
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[18]VAN DIGGELEN F S T.A-GPS:Assisted GPS,GNSS,and SBAS[M].London:Artech House,2009.
[19]谢钢.GPS原理与接收机设计[J].北京:电子工业出版社,2009.XIE G.Principles of GPS and recievers design[J].Beijing:Publishing House of Electronics Industry,2009.
[20]郑伦贵,尤政,张高飞,等.基于非相干积分的GNSS弱信号捕获[J].清华大学学报(自然科学版),2014(6):794-798.ZHENG L G,YOU Z,ZHANG G F,et al.Acquisition of weak GNSS signals based on non-coherent integration[J].Journal of Tsinghua University(Science and Technology),2014(6):794-798(in Chinese).
[21]HURD W J,STATMAN J I,VILNROTTER V A.High dynamic GPS receiver using maximum likelihood estimation and frequency tracking[J].IEEE Transactions on Aerospace and Electronic Systems,1987,23(4):425-437.
[2]KAPLAN E,HEGARTY C.Understanding GPS:Principles and applications[M].2nd ed.Norwood:Artech House,Inc.,2006:459-460.
[3]程俊仁,刘光斌,姚志成,等.一种鲁棒GNSS矢量跟踪环[J].航空学报,2014,35(11):3106-3114.CHENG J R,LIU G B,YAO Z C,et al.A robust GNSS vector tracking loop[J].Acta Aeronautica et Astronautica Sinica,2014,35(11):3106-3114(in Chinese).
[4]阮航,刘峰,张磊,等.一种改进的非相干GNSS信号频率锁定方法[J].华中科技大学学报:自然科学版,2014(5):122-127.YUAN H,LIU F,ZHANG L,et al.Improved non-coherent accumulation GNSS weak signal frequency tracking approach[J].Journal of Huazhong University of Science and Technology(Natural Science Edition),2014(5):122-127(in Chinese).
[5]段瑞枫,刘荣科,周游,等.一种低复杂度的极低信噪比高动态信号载波粗捕获算法[J].航空学报,2013,34(3):662-669.DUAN R F,LIU R K,ZHOU Y,et al.A low-complexity coarse acquisition algorithm for signals with extremely low signal noise ratio and high dynamics[J].Acta Aeronautica et Astronautica Sinica,2013,34(3):662-669(in Chinese).
[6]LASHLEY M,BEVLY D M.Vector delay/frequency lock loop implementation and analysis[C]∥Proceedings of the Institute of Navigation,2009:1073-1086.
[7]CURRAN J T,LACHAPELLE G,MURPHY C C.Improving the design of frequency lock loops for GNSS receivers[J].IEEE Transactions on Aerospace and Electronic Systems,2012,48(1):850-868.
[8]TANG X,FALLETTI E,LO PRESTI L.Fast nearly ML estimation of Doppler frequency in GNSS signal acquisition process[J].Sensors,2013,13(5):5649-5670.
[9]李寅寅,徐晓苏,刘锡祥.基于半比特交替和FFT组合的GPS软件接收机弱信号捕获算法[J].中国惯性技术学报,2012,20(1):46-50.LI Y Y,XU X S,LIU X X.Acquisition algorithm based on half-bit alternation and FFT combination for weak signals of GPS software receiver[J].Journal of Chinese Inertial Technology,2012,20(1):46-50(in Chinese).
[10]YANG C.Tracking of GPS code phase and carrier frequency in the frequency domain[C]∥Proceedings of the16th International Technical Meeting of the Satellite Division of The Institute of Navigation,2001:628-637.
[11]KRASNER N F.Method for open loop tracking GPS signals:U.S.Patent 6633255[P].2003-10-14.
[12]巴晓辉,刘海洋,陈培,等.一种超高灵敏度GPS信号的跟踪方法[J].武汉大学学报(信息科学版),2009,34(11):1368-1371.BA X H,LIU H Y,CHEN P,et al.A novel algorithm for ultra high-sensitivity GPS tracking[J].Geomatics and Information Science of Wuhan University,2009,34(11):1368-1371(in Chinese).
[13]BA X,LIU H,ZHENG R,et al.A novel algorithm based on FFT for ultra high-sensitivity GPS tracking[C]∥Proceedings of the 22nd International Technical Meeting of The Satellite Division of the Institute of Navigation,2001:1700-1706.
[14]YAN K,ZIEDAN N I,ZHANG H,et al.Weak GPS signal tracking using FFT discriminator in open loop receiver[J].GPS Solutions,2016,20(2):225-237.
[15]梅浩,战兴群,李源,等.城市道路GNSS脆弱性评估技术[J].哈尔滨工业大学学报,2017,49(4):101-107.MEI H,ZHAN X Q,LI Y,et al.A GNSS vulnerability assessment technique of urban roads[J].Journal of Harbin Institute of Technology,2017,49(4):101-107(in Chinese).
[16]富立,王淼,王玲玲.高动态GPS载波锁相环切换稳定性分析[J].航空学报,2013,34(11):2572-2579.FU L,WANG M,WANG L L.Stability analysis of high dynamic GPS carrier phase-locked loop via switching system[J].Acta Aeronautica et Astronautica Sinica,2013,34(11):2572-2579(in Chinese).
[17]齐巍,常青,张其善,等.高动态信号模拟器中的多普勒模拟算法[J].航空学报,2008,29(5):1252-1257.QI W,CHANG Q,ZHANG Q S,et al.Arithmetic of Doppler simulation in high dynamic signal simulator[J].Acta Aeronautica et Astronautica Sinica,2008,29(5):1252-1257(in Chinese).
[18]VAN DIGGELEN F S T.A-GPS:Assisted GPS,GNSS,and SBAS[M].London:Artech House,2009.
[19]谢钢.GPS原理与接收机设计[J].北京:电子工业出版社,2009.XIE G.Principles of GPS and recievers design[J].Beijing:Publishing House of Electronics Industry,2009.
[20]郑伦贵,尤政,张高飞,等.基于非相干积分的GNSS弱信号捕获[J].清华大学学报(自然科学版),2014(6):794-798.ZHENG L G,YOU Z,ZHANG G F,et al.Acquisition of weak GNSS signals based on non-coherent integration[J].Journal of Tsinghua University(Science and Technology),2014(6):794-798(in Chinese).
[21]HURD W J,STATMAN J I,VILNROTTER V A.High dynamic GPS receiver using maximum likelihood estimation and frequency tracking[J].IEEE Transactions on Aerospace and Electronic Systems,1987,23(4):425-437.