高动态扩频信号快速捕获方法的研究与实现
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摘要
卫星导航定位系统可以为公路、铁路、空中和海上的交通运输工具提供导航定位服务。它能够军民两用,战略作用与商业利益并举。只要持有便携式接收机,则无论身处陆地、海上还是空中,都能接收卫星发出的特定信号。接收机中的电脑选取几颗卫星发出的信号进行分析,就能确定接收机持有者的位置。
卫星导航定位系统的理论基础是扩频通信理论,扩频通信技术与常规的通信技术相比,具有低截获率、强抗噪声、抗干扰性、信息隐蔽和多址通信等特点,目前己从军事领域向民用领域迅速发展,成为进入信息时代的三大高技术通信传输方式之一。扩频通信技术中,最常见的是直接序列扩频通信(DS-SS)系统,本论文所研究的就是这一类通信系统。
扩频信号的快速捕获是扩频通信中的一个关键性问题。扩频信号的捕获,既要完成载波频率的捕获,又要完成伪码相位的捕获,是一个二维的捕获过程。高动态扩频信号具有高达上百kHz的载波多普勒频移,大大增加了捕获难度。本论文在第三章对长码(P码)的快速捕获进行了深入的分析,基于对国内外相关文献中长码快速捕获方法的分析与对比,并且结合在实际过程中硬件资源需求的考虑,提出了基于存储补零部分相关的FFT长码快速捕获方法。该方法在搜索到伪码相位的同时能估计出载波多普勒频移,从而将载波频率、伪码相位的二维捕获过程变为伪码相位的一维捕获过程,大大减少捕获时间。
本论文对基于存储补零部分相关的FFT长码快速捕获设计的结构和性能进行了分析,提出了改善基于存储补零部分相关的FFT长码快速捕获设计方案性能的方法,并给出了仿真结果,结果表明基于存储补零部分相关的FFT长码快速捕获设计能有效解决高动态扩频信号的快速捕获问题。
本论文提出的长码快速捕获设计是在实际工程中提出的,该伪码捕获方法最终在FPGA开发板上得到了实现和验证,并且在第四章给出了长码捕获的FPGA实现,并对各主要子模块进行了详细地分析。其研究成果不但可以适用于高动态的卫星导航接收机,对普通的导航定位接收机仍然适用。
Nabigation Positioning Ststem(NPS) can be used to offer the Nabigation Positioning Service for the conveyanve of road,railway ,the air and the sea.It can be uesd for army and civilian,and it has traffic function and business behalf.It consists of several secondary planets,wich go around the earch and the blaze away wireless signal.No matter where you are,on the land ,in the sea or in the air,if only you have a receiver on hand,you can receive the signal eradiated by the secondary planet.The computer in the receiver choose several swalth ti analysee,in this way,you can make sure where you are.
Compared to other communication technologies, Spread Spectrum(SS) technology has the advantages of low probability of intercepting, a high immunity to interference, hiding the useful information and multiple-access communication ability. In modern information times, it has been one of the three high-technological communication means and is developing from military use to commercial environment. In this dissertation, the author mostly research on Direct Sequence Spread Spectrum (DS-SS), the most ordinary one within Spread Spectrum technologies.
Fast acquisition process of spread spectrum signals is crucial in direct sequence spread spectrum (DS-SS) communications. The acquisition process has to search both carrier frequency Doppler shift and PN code phase, so the whole acquisition process is a two-dimensional search process. The high dynamic spread spectrum signals include high Doppler shifts which may exceed 100 kHz, largely increases the difficulties of acquisition process. Compared to traditional acquisition method, this dissertation utilizes an FFT-based partial correlation by partition and zero padding acquisition method to search the correct code phase and estimate the carrier Doppler shifts simultaneously. By using this method, the former two-dimensional acquisition process becomes a one-dimensional process and reduces the acquisition time.
The structure and the performance of the FFT-based partial correlation by partition and zero padding acquisition method are analyzed and several ways are proposed to improve the method in this dissertation. The performance of the method is simulated in this dissertation and the simulation results show that the method can efficiently perform the acquisition process of the high dynamic spread spectrum signals.
In this dissertation, the P code acquisition is realized in FPGA. The research result of this dissertation can be applied in the high dynamic satellite navigation receiver as well as the ordinary satellite navigation receiver.
卫星导航定位系统的理论基础是扩频通信理论,扩频通信技术与常规的通信技术相比,具有低截获率、强抗噪声、抗干扰性、信息隐蔽和多址通信等特点,目前己从军事领域向民用领域迅速发展,成为进入信息时代的三大高技术通信传输方式之一。扩频通信技术中,最常见的是直接序列扩频通信(DS-SS)系统,本论文所研究的就是这一类通信系统。
扩频信号的快速捕获是扩频通信中的一个关键性问题。扩频信号的捕获,既要完成载波频率的捕获,又要完成伪码相位的捕获,是一个二维的捕获过程。高动态扩频信号具有高达上百kHz的载波多普勒频移,大大增加了捕获难度。本论文在第三章对长码(P码)的快速捕获进行了深入的分析,基于对国内外相关文献中长码快速捕获方法的分析与对比,并且结合在实际过程中硬件资源需求的考虑,提出了基于存储补零部分相关的FFT长码快速捕获方法。该方法在搜索到伪码相位的同时能估计出载波多普勒频移,从而将载波频率、伪码相位的二维捕获过程变为伪码相位的一维捕获过程,大大减少捕获时间。
本论文对基于存储补零部分相关的FFT长码快速捕获设计的结构和性能进行了分析,提出了改善基于存储补零部分相关的FFT长码快速捕获设计方案性能的方法,并给出了仿真结果,结果表明基于存储补零部分相关的FFT长码快速捕获设计能有效解决高动态扩频信号的快速捕获问题。
本论文提出的长码快速捕获设计是在实际工程中提出的,该伪码捕获方法最终在FPGA开发板上得到了实现和验证,并且在第四章给出了长码捕获的FPGA实现,并对各主要子模块进行了详细地分析。其研究成果不但可以适用于高动态的卫星导航接收机,对普通的导航定位接收机仍然适用。
Nabigation Positioning Ststem(NPS) can be used to offer the Nabigation Positioning Service for the conveyanve of road,railway ,the air and the sea.It can be uesd for army and civilian,and it has traffic function and business behalf.It consists of several secondary planets,wich go around the earch and the blaze away wireless signal.No matter where you are,on the land ,in the sea or in the air,if only you have a receiver on hand,you can receive the signal eradiated by the secondary planet.The computer in the receiver choose several swalth ti analysee,in this way,you can make sure where you are.
Compared to other communication technologies, Spread Spectrum(SS) technology has the advantages of low probability of intercepting, a high immunity to interference, hiding the useful information and multiple-access communication ability. In modern information times, it has been one of the three high-technological communication means and is developing from military use to commercial environment. In this dissertation, the author mostly research on Direct Sequence Spread Spectrum (DS-SS), the most ordinary one within Spread Spectrum technologies.
Fast acquisition process of spread spectrum signals is crucial in direct sequence spread spectrum (DS-SS) communications. The acquisition process has to search both carrier frequency Doppler shift and PN code phase, so the whole acquisition process is a two-dimensional search process. The high dynamic spread spectrum signals include high Doppler shifts which may exceed 100 kHz, largely increases the difficulties of acquisition process. Compared to traditional acquisition method, this dissertation utilizes an FFT-based partial correlation by partition and zero padding acquisition method to search the correct code phase and estimate the carrier Doppler shifts simultaneously. By using this method, the former two-dimensional acquisition process becomes a one-dimensional process and reduces the acquisition time.
The structure and the performance of the FFT-based partial correlation by partition and zero padding acquisition method are analyzed and several ways are proposed to improve the method in this dissertation. The performance of the method is simulated in this dissertation and the simulation results show that the method can efficiently perform the acquisition process of the high dynamic spread spectrum signals.
In this dissertation, the P code acquisition is realized in FPGA. The research result of this dissertation can be applied in the high dynamic satellite navigation receiver as well as the ordinary satellite navigation receiver.
引文
[1] David M. Lin and James B. Y. Tsui. Comparison of Acquisition Methods for Software GPS Receiver. Proceedings of ION GPS 2000,2000.9.
[2] Yang, C. FFT Acquisition of Periodic,Aperiodic, and Overlaid Code Sequences in GPS. Proceedings of ION GPS 2001,2001.9.
[3] David M. Lin and James B. Y. An Efficient Weak Signal Acquisition Algorithm for a Software GPS Receiver. Proceedings of of ION GPS 2001,2001.9.
[4] Van Nee, D.J.R. and Coenen, A.J.R.M. New Fast GPS Code- Acquisition Technique Using FFT. Electronics Letters,Vol. 27, Issue:2,1991:158-160.
[5] Sascha M. Spangenberg, Iain Scott, Stephen McLaughlin, Gordon J.R..Povey, David G.M. Cruickshank and Peter M. Grant. An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communication Systems. Wireless Personal Communications 12,2000:27-56.
[6] Grant, P.M. and Spangenberg, S.M. Doppler estimation for fast acquisition in spread spectrum communication systems. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEESth Inernational Symposium on, vol.l,1998:106-110.
[7] Candida L Spillard, Sascha M Spangenberg, Gordon J R Povey. A Serial-parallel FFT Correlator for PN Code Acquisition from LEO Satellites. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEE 5th International Symposium on: 446-448.
[8] B. Sklar. A structured Overview of Digital communications-A Tutorial Review-PartⅠ, [J]. IEEE Communications Magazine, 1983.8.
[9]徐穆洵.直扩通信干扰研究.电子对抗,1994(4):38-48.
[10]李廷军,曹建平,徐宇如,等.码分多址方案分析.现代电子技术,2001(12):29-33.
[11]肖国镇,梁传甲.伪随机序列及其应用.北京:国防工业出版社,1985:54-58
[12]林可祥,汪一飞.伪随机码原理与应用.北京:人民邮电出版社,1978:42-47
[13]沈允春.扩谱技术.北京:国防工业出版社,1995:28-89
[14] A. Q. Hu, P.C.K Kwork, T.S.Ng. MPSK DS/CDMA carrier recovery and tracking based on correlation technique. Electronics Letters, 1999.2,35(3):201-203.
[15] Sascha M.Spangenberg, et al. An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communications 13:27-56, 2000.
[16]王世一.数字信号处理(修订版).北京:北京理工大学出版社,1997: 107-110.
[17]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,1997:81-84.
[18]郭肃丽,刘云飞.一种基于FFT的伪码快捕方法.无线电通信技术,2003,29(11):24-27
[19] Harris J.G. On the Use of Windows for Harnonic Analysis with the Discrete Fourier Tranform, Proceedings of the IEEE, Vol.66, 1978:51-83.
[20] Polydros A. and Weber C.L., A Unified Approach to Serial Search Speread Spectrum Code Acaquisition, PartⅠ/Ⅱ, IEEE Trans. Commun., 1984:Vol.Com-32, No.5:549-560.
[21] Ward R.B and Sarwate D.V., Acqusition of Pseudonoise Siginals by Recursion-Aided Sequential Estimation, IEEE Trans. Commun, 1997, Vol. COM-25:784-794.
[22] Grant, P.M. and Spangenberg, S.M. Doppler Estimation for Fast Acquisition in Spread Spectrum Communication Systems. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEE5th International Symposiumon, Vol.1, 1998:106-110.
[23]杨小牛,楼才义,徐建良,等.软件无线电原理与应用.北京:电子工业出版社,2001:35-96
[24]赵雅兴. FPGA原理、设计与应用.天津:天津大学出版社,1999:22-56
[25] D E Knuth.the art of Computer Programming.Vol.3:sorting and searching,Boston: Addiso-wesley, 1973.
[26]周建钦.排序和查找理论及算法.北京:科学出版社,1993:32-78
[27]徐世伟,刘严严,刘红侠,等.异步时钟亚稳态的产生及解决方法.电子技术应用,2006(11):14-17
[28] Chun Yang. Fast Code Acquisition with FFT and its Sampling Schemes. Proceedings of 1996 National Technical Meeting. USA, ION, 1996.
[29] Chun Yang. FFT Acquisition of Periodic, Aperiodic, Puncture, and Overlaid Code Sequences in GPS. Proceedings of ION GPS 2001. Salt Lake City:The Institute of Navigation, Sept,2001.
[30] A.J.Viterbi. CDMA扩频通信原理.北京:人民邮电出版社,1997:32-65
[31] M.May, A.Brown, B.Tanju. Applications of Digital Storage Reciever for Enhanced Signal Processing. Proceedings of ION GPS-99, Nashville, TN:The Institute of Navigation, Sept.1999.
[32] A. Jovancevic, A.Brown, S.Ganguly et.al. Open Architecture GPS Receiver.Proceedings of ION 57th Annual Meeting. Albuquerque, NM: ION,June,2001.
[33]任亚安,王鹏. GPS中P(Y)码直接捕获技术的研究进展,全球定位系统,2003(2):68-73.
[34]余湋.GPS扩频码的同步技术研究:[电子科大硕士学位论文].成都:电子科技大学,2007:35-40.
[2] Yang, C. FFT Acquisition of Periodic,Aperiodic, and Overlaid Code Sequences in GPS. Proceedings of ION GPS 2001,2001.9.
[3] David M. Lin and James B. Y. An Efficient Weak Signal Acquisition Algorithm for a Software GPS Receiver. Proceedings of of ION GPS 2001,2001.9.
[4] Van Nee, D.J.R. and Coenen, A.J.R.M. New Fast GPS Code- Acquisition Technique Using FFT. Electronics Letters,Vol. 27, Issue:2,1991:158-160.
[5] Sascha M. Spangenberg, Iain Scott, Stephen McLaughlin, Gordon J.R..Povey, David G.M. Cruickshank and Peter M. Grant. An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communication Systems. Wireless Personal Communications 12,2000:27-56.
[6] Grant, P.M. and Spangenberg, S.M. Doppler estimation for fast acquisition in spread spectrum communication systems. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEESth Inernational Symposium on, vol.l,1998:106-110.
[7] Candida L Spillard, Sascha M Spangenberg, Gordon J R Povey. A Serial-parallel FFT Correlator for PN Code Acquisition from LEO Satellites. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEE 5th International Symposium on: 446-448.
[8] B. Sklar. A structured Overview of Digital communications-A Tutorial Review-PartⅠ, [J]. IEEE Communications Magazine, 1983.8.
[9]徐穆洵.直扩通信干扰研究.电子对抗,1994(4):38-48.
[10]李廷军,曹建平,徐宇如,等.码分多址方案分析.现代电子技术,2001(12):29-33.
[11]肖国镇,梁传甲.伪随机序列及其应用.北京:国防工业出版社,1985:54-58
[12]林可祥,汪一飞.伪随机码原理与应用.北京:人民邮电出版社,1978:42-47
[13]沈允春.扩谱技术.北京:国防工业出版社,1995:28-89
[14] A. Q. Hu, P.C.K Kwork, T.S.Ng. MPSK DS/CDMA carrier recovery and tracking based on correlation technique. Electronics Letters, 1999.2,35(3):201-203.
[15] Sascha M.Spangenberg, et al. An FFT-Based Approach for Fast Acquisition in Spread Spectrum Communications 13:27-56, 2000.
[16]王世一.数字信号处理(修订版).北京:北京理工大学出版社,1997: 107-110.
[17]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,1997:81-84.
[18]郭肃丽,刘云飞.一种基于FFT的伪码快捕方法.无线电通信技术,2003,29(11):24-27
[19] Harris J.G. On the Use of Windows for Harnonic Analysis with the Discrete Fourier Tranform, Proceedings of the IEEE, Vol.66, 1978:51-83.
[20] Polydros A. and Weber C.L., A Unified Approach to Serial Search Speread Spectrum Code Acaquisition, PartⅠ/Ⅱ, IEEE Trans. Commun., 1984:Vol.Com-32, No.5:549-560.
[21] Ward R.B and Sarwate D.V., Acqusition of Pseudonoise Siginals by Recursion-Aided Sequential Estimation, IEEE Trans. Commun, 1997, Vol. COM-25:784-794.
[22] Grant, P.M. and Spangenberg, S.M. Doppler Estimation for Fast Acquisition in Spread Spectrum Communication Systems. Spread Spectrum Techniques and Applications, 1998. Proceedings. 1998 IEEE5th International Symposiumon, Vol.1, 1998:106-110.
[23]杨小牛,楼才义,徐建良,等.软件无线电原理与应用.北京:电子工业出版社,2001:35-96
[24]赵雅兴. FPGA原理、设计与应用.天津:天津大学出版社,1999:22-56
[25] D E Knuth.the art of Computer Programming.Vol.3:sorting and searching,Boston: Addiso-wesley, 1973.
[26]周建钦.排序和查找理论及算法.北京:科学出版社,1993:32-78
[27]徐世伟,刘严严,刘红侠,等.异步时钟亚稳态的产生及解决方法.电子技术应用,2006(11):14-17
[28] Chun Yang. Fast Code Acquisition with FFT and its Sampling Schemes. Proceedings of 1996 National Technical Meeting. USA, ION, 1996.
[29] Chun Yang. FFT Acquisition of Periodic, Aperiodic, Puncture, and Overlaid Code Sequences in GPS. Proceedings of ION GPS 2001. Salt Lake City:The Institute of Navigation, Sept,2001.
[30] A.J.Viterbi. CDMA扩频通信原理.北京:人民邮电出版社,1997:32-65
[31] M.May, A.Brown, B.Tanju. Applications of Digital Storage Reciever for Enhanced Signal Processing. Proceedings of ION GPS-99, Nashville, TN:The Institute of Navigation, Sept.1999.
[32] A. Jovancevic, A.Brown, S.Ganguly et.al. Open Architecture GPS Receiver.Proceedings of ION 57th Annual Meeting. Albuquerque, NM: ION,June,2001.
[33]任亚安,王鹏. GPS中P(Y)码直接捕获技术的研究进展,全球定位系统,2003(2):68-73.
[34]余湋.GPS扩频码的同步技术研究:[电子科大硕士学位论文].成都:电子科技大学,2007:35-40.