GPS信号C/A码跟踪的FPGA实现
摘要
GPS全球定位系统是美国国防部为军事目的而建立的卫星导航系统,其主要目的是解决海上、陆地和空中运载工具的导航定位问题。GPS作为新一代卫星导航系统,不仅具有全球、全天候、连续、高精度导航与定位能力,而且具有优良的抗干扰性和保密性。因此,发展全球定位系统是当今导航技术现代化的一个重要标志。
在GPS接收机中,为了得到导航电文并对其进行解算,要完成复杂的信号处理过程。其中,怎样捕获到卫星信号,并对C/A码进行跟踪是研制GPS接收机的重要问题之一。本文在对GPS信号的结构进行深入的分析后,结合FPGA的特点,对算法进行设计及优化后,给出了相应的仿真。
本文的内容主要包括以下几个方面:
1.对GPS信号结构的产生原理进行了深入地分析,并对GPS信号的调制机理进行详细地阐述。
2.在GPS信号的捕获方面,采用了基于FFT频域的快速捕获的方法,即将接收到的GPS信号先利用快速傅立叶变换(FFT)变换到频域,在频域完成相应的运算后,再利用傅立叶反变换(IFFT)变换到时域。从而大大减少了计算量,加快了信号捕获的速度,提高了捕获性能。
3.在C/A码跟踪部分,本文采用了非相干延迟锁定环对C/A码进行跟踪。来自载波跟踪环路的本地载波将输入的信号变成基带信号,然后分别和本地码的三个不同相位序列进行相乘,将相乘结果进行累加,经过处理将得到码相位和当前的载波频率送到载波跟踪环路。
4.载波跟踪环,本文采用的是科斯塔斯环。载波跟踪环和码跟踪环在结构上相似,故本文只对关键的载波NCO进行了仿真。
本文的创新点主要是使用FPGA对整个GPS信号的捕获及C/A码的跟踪进行设计。此外,根据FPGA的特点,在不改变外部硬件设计的前提下,改变相应的IP核或相关的VHDL程序就可对系统进行各种优化设计,以适应不同类型的GPS接收机的不同功能。
Global positioning system (GPS) is a satellite navigation system established to solve the navigating and positioning problems on land or sea and in the air. As a new generation of satellite navigation system, it not only has global, round-the-clock, continuous, high-precision navigating and positioning functions, but also possesses excellent interference immunity and confidentiality. Therefore, the development of GPS navigation technology has become ever more important in the advancement of navigation industry.
In order to receive navigation messages and calculate their values, it is necessary to complete complex signal processing in the GPS receiver, while how to capture the satellite signals and track the C/A code is one of the most important issues. In this paper, the corresponding simulation results of GPS signals were provided based on the detailed GPS signal's structure analyses, FPGA features, and optimized algorithm.
The contents of this paper include the following aspects:
1. An in-depth study on the structure and theory of GPS signal is conducted, and the modulation mechanisms of GPS signal are explained in detail.
2. To capture the GPS signal, a rapid acquisition method based on the FFT parallel code is employed. The incoming signals are firstly translated into frequency domain and correlated, and then the results are translated back to the time domain by using IFFT. Accordingly, a much more complex computation is avoided and the searching speed for GPS signals is much faster than sequential detecting technique.
3. A non-coherent DLL is used to track the C/A code. The local carriers from carrier tracking loop turn the input signals into the baseband signal, and the baseband signals multiply the three different phase sequence of the local yards, then deal with cumulative results, at last, put the code phase and current carrier frequency into carrier tracking loop.
4. Costas loop is used as the carrier tracking loop. It is similar to the C/A tracking loop in structure. Thus, only the simulation of carrier NCO has been given in this paper.
In this paper, a novel approach by using FPGA to capture the GPS signals and track the C/A codes is employed. According to the characteristics of FPGA, various system optimizations could be realized by just changing the corresponding IP core or related VHDL program without changing any hardware. The advantages and flexibility of the novel approach are easily adapted to the different functions of the different GPS receivers.
在GPS接收机中,为了得到导航电文并对其进行解算,要完成复杂的信号处理过程。其中,怎样捕获到卫星信号,并对C/A码进行跟踪是研制GPS接收机的重要问题之一。本文在对GPS信号的结构进行深入的分析后,结合FPGA的特点,对算法进行设计及优化后,给出了相应的仿真。
本文的内容主要包括以下几个方面:
1.对GPS信号结构的产生原理进行了深入地分析,并对GPS信号的调制机理进行详细地阐述。
2.在GPS信号的捕获方面,采用了基于FFT频域的快速捕获的方法,即将接收到的GPS信号先利用快速傅立叶变换(FFT)变换到频域,在频域完成相应的运算后,再利用傅立叶反变换(IFFT)变换到时域。从而大大减少了计算量,加快了信号捕获的速度,提高了捕获性能。
3.在C/A码跟踪部分,本文采用了非相干延迟锁定环对C/A码进行跟踪。来自载波跟踪环路的本地载波将输入的信号变成基带信号,然后分别和本地码的三个不同相位序列进行相乘,将相乘结果进行累加,经过处理将得到码相位和当前的载波频率送到载波跟踪环路。
4.载波跟踪环,本文采用的是科斯塔斯环。载波跟踪环和码跟踪环在结构上相似,故本文只对关键的载波NCO进行了仿真。
本文的创新点主要是使用FPGA对整个GPS信号的捕获及C/A码的跟踪进行设计。此外,根据FPGA的特点,在不改变外部硬件设计的前提下,改变相应的IP核或相关的VHDL程序就可对系统进行各种优化设计,以适应不同类型的GPS接收机的不同功能。
Global positioning system (GPS) is a satellite navigation system established to solve the navigating and positioning problems on land or sea and in the air. As a new generation of satellite navigation system, it not only has global, round-the-clock, continuous, high-precision navigating and positioning functions, but also possesses excellent interference immunity and confidentiality. Therefore, the development of GPS navigation technology has become ever more important in the advancement of navigation industry.
In order to receive navigation messages and calculate their values, it is necessary to complete complex signal processing in the GPS receiver, while how to capture the satellite signals and track the C/A code is one of the most important issues. In this paper, the corresponding simulation results of GPS signals were provided based on the detailed GPS signal's structure analyses, FPGA features, and optimized algorithm.
The contents of this paper include the following aspects:
1. An in-depth study on the structure and theory of GPS signal is conducted, and the modulation mechanisms of GPS signal are explained in detail.
2. To capture the GPS signal, a rapid acquisition method based on the FFT parallel code is employed. The incoming signals are firstly translated into frequency domain and correlated, and then the results are translated back to the time domain by using IFFT. Accordingly, a much more complex computation is avoided and the searching speed for GPS signals is much faster than sequential detecting technique.
3. A non-coherent DLL is used to track the C/A code. The local carriers from carrier tracking loop turn the input signals into the baseband signal, and the baseband signals multiply the three different phase sequence of the local yards, then deal with cumulative results, at last, put the code phase and current carrier frequency into carrier tracking loop.
4. Costas loop is used as the carrier tracking loop. It is similar to the C/A tracking loop in structure. Thus, only the simulation of carrier NCO has been given in this paper.
In this paper, a novel approach by using FPGA to capture the GPS signals and track the C/A codes is employed. According to the characteristics of FPGA, various system optimizations could be realized by just changing the corresponding IP core or related VHDL program without changing any hardware. The advantages and flexibility of the novel approach are easily adapted to the different functions of the different GPS receivers.
引文
[1]任晓东文博,CPLD/FPGA高级应用开发指南[M],北京:电子工业出版社,2003,26-34
[2]王大新 张立本 赵军,车载GPS导航产业发展现状与趋势[J],卫星应用,2005(4)
[3]陈俊勇GPS现代化和GPS信号重构技术的进展[J],全球定位系统,2005
[4]徐绍铨,GPS测量原理及应用[M],武汉:武汉大学出版社,2003,54-75
[5]张勤,GPS测量原理及应用[M],北京:科学出版社,2005,85-102
[6]李天文,GPS原理及应用[M],北京:科学出版社,2003,65-93
[7]刘基余,GPS卫星导航定位原理与方法[M],北京:科学出版社,2006,85-102
[8]袁安存,全球定位系统(GPS)原理与应用[M],大连:大连海事大学出版社,1999,23-69
[9]李明峰 冯宝红 刘三枝,GPS定位技术及其应用[M],北京:国防工业出版社,2006
[10]王福昌 熊兆飞 黄本雄,通信原理[M],北京:清华大学出版社,2006
[11]王惠南,GPS导航原理与应用[M],北京:科学出版社,2003,52-95
[12]Elliott D.Kaplan,GPS原理与应用[M](邱致和 王万义译),北京:电子工业出版社,2002
[13]Ganguly S.A.Jovancevic,M.Kirchner,GPS Signal Reconstitution[A].Proceeding of ION.GNSS2004[C],Long Beach,CA.USA,2004
[14]Ward P.,GPS Receiver Search Techniques[A].IEEE PLANS[C].1996
[15]陈凌,基于FFT的扩频信号载波频率捕获研究与实现[D],硕士学位论文,西南交通大学,2004
[16]魏敬法,GPS信号快速捕获的FPGA实现[D],硕士学位论文,中科院研究生院,2005
[17]王福昌 鲁昆生,锁相技术[M],武汉:华中科技大学出版社,1997
[18]张厥盛 郑继禹 万心平,锁相技术[M],西安:西安电子科技大学出版社,1994,86-110
[19]Braasch M.Van Dierendonck A.GPS Receiver Architectures and Measurements[J]Proceedings of IEEE,1999,87(1)
[20]孙礼,GPS接收机系统的研究[D],博士学位论文,北京航空航天大学,1998
[21]孙礼 王银锋 何川,GPS信号捕获与跟踪策略确定及实现[J],北京航空航天大学学报1999.25(2)
[22]黄智伟,GPS接收机电路设计[M],北京:国防工业出版社,2005
[23]刘大杰,全球定位系统(GPS)的原理与数据处理[M],同济大学出版社,2001
[24]熊小莉,直接序列扩频信号数字科斯塔斯环的分析与设计[J],电讯技术,2001(4)
[25]王诚 吴继华 范丽珍等,Altera FPGA/CPLD设计[M],北京:人民邮电出版社,2005,1-23
[26]李洪伟 袁斯华,基于Quartus Ⅱ的FPGA/CPLD设计fMl,北京:电子工业出版社,2006
[27]任爱峰 初秀芹,基于FPGA的嵌入式系统设计[M],西安:西安电子科技大学出版社,2004
[28]Altera,Cyclone Device Handbook[Z],http://www.altera.com,1994
[29]潘松 黄继业,EDA技术实用教程[M],北京:科学出版社2002,10-38
[30]Paulo S.R.Diniz Eduardo A.B.da Silva Sergio L.Netto,数字信号处理系统分析与设计[M]. (门爱东等译),北京:电子工业出版社,2004
[31]胡广书,数字信号处理—理论、算法与实现[M],北京:清华大学出版社,2003
[32]张欣,扩频通信数字基带信号处理算法及其VLSI实现[M],北京:科学出版社,2004
[33]程佩青,数字滤波与快速傅立叶变换[M],北京:清华大学出版社,1990
[34]Emmanuel C.Ifeachor Barrie W.Jervis.,数字信号处理实践方法[M](罗鹏飞等译),北京:电子工业出版社,2004
[35]Uwe Meyer-Baese,数字信号处理的FPGA实现(第二版)[M](刘凌,胡永生译),北京:清华大学出版社,2006
[36]Coenen AVan Nee D.Novel,Fast GPS/GLONSS Code Acquisition[J].Electronics Letters,1992,28(9)
[37]王运盛,基于DSP的GPS/DR组合导航系统设计[D],硕士学位论文,武汉大学,2004
[38]Gunawardena S.Feasibility,Study for the Implementation of Global Positioning System Block Processing Techniques in Field Programmable Gate Arrays[D].Ohio University,2000.
[39]Cohn M.Lemple A.On Fast M-Sequence Transforms[J]IEEE Transactions on Information Theory 1997
[40]ICD-GPS-200:Interface Control Document[Z],USA,ARINC Research,1997.
[41]赵明忠,基于FPGA技术的数字相关器的设计与实现[J],电子应用技术,2002(28)
[42]孙学军 王秉均,通信原理[M],北京:电子工业出版社,2001
[43]安效君 王力男,NCO的数字化实现及应用[J],无线电通信技术,2004(30)
[44]齐洪喜 陆颖,VHDL电路设计实用教程[M1,北京:清华大学出版社,2004
[45]A.J维特比,CDMA扩频通信原理(李世鹤 鲍刚 彭容译)[M],北京:人民邮电出版社,1997
[46]庞浩 王赞草,一种基于FPGA实现的全数字锁相环[J],电子技术应用,2005(5)
[47]阿兰.布兰查德,锁相环及其在相干接收机设计中的应用(向永正 曹献枕译)[M],北京:人民邮电出版社,1980
[48]Alaqeeli A.,Global Positioning System Signal Acquisition and Tracking Using Field Programmable Gate Arrays[D].Ohio University,2002
[49]李洪涛,GPS应用程序设计[M],北京:科学出版社,1999
[50]Mattos Philip G.Intergraded GPS and Dead Reckoning for low-cost vehicle navigation and tracking[J]IEEE Transactions on Automatic Control,1995
[2]王大新 张立本 赵军,车载GPS导航产业发展现状与趋势[J],卫星应用,2005(4)
[3]陈俊勇GPS现代化和GPS信号重构技术的进展[J],全球定位系统,2005
[4]徐绍铨,GPS测量原理及应用[M],武汉:武汉大学出版社,2003,54-75
[5]张勤,GPS测量原理及应用[M],北京:科学出版社,2005,85-102
[6]李天文,GPS原理及应用[M],北京:科学出版社,2003,65-93
[7]刘基余,GPS卫星导航定位原理与方法[M],北京:科学出版社,2006,85-102
[8]袁安存,全球定位系统(GPS)原理与应用[M],大连:大连海事大学出版社,1999,23-69
[9]李明峰 冯宝红 刘三枝,GPS定位技术及其应用[M],北京:国防工业出版社,2006
[10]王福昌 熊兆飞 黄本雄,通信原理[M],北京:清华大学出版社,2006
[11]王惠南,GPS导航原理与应用[M],北京:科学出版社,2003,52-95
[12]Elliott D.Kaplan,GPS原理与应用[M](邱致和 王万义译),北京:电子工业出版社,2002
[13]Ganguly S.A.Jovancevic,M.Kirchner,GPS Signal Reconstitution[A].Proceeding of ION.GNSS2004[C],Long Beach,CA.USA,2004
[14]Ward P.,GPS Receiver Search Techniques[A].IEEE PLANS[C].1996
[15]陈凌,基于FFT的扩频信号载波频率捕获研究与实现[D],硕士学位论文,西南交通大学,2004
[16]魏敬法,GPS信号快速捕获的FPGA实现[D],硕士学位论文,中科院研究生院,2005
[17]王福昌 鲁昆生,锁相技术[M],武汉:华中科技大学出版社,1997
[18]张厥盛 郑继禹 万心平,锁相技术[M],西安:西安电子科技大学出版社,1994,86-110
[19]Braasch M.Van Dierendonck A.GPS Receiver Architectures and Measurements[J]Proceedings of IEEE,1999,87(1)
[20]孙礼,GPS接收机系统的研究[D],博士学位论文,北京航空航天大学,1998
[21]孙礼 王银锋 何川,GPS信号捕获与跟踪策略确定及实现[J],北京航空航天大学学报1999.25(2)
[22]黄智伟,GPS接收机电路设计[M],北京:国防工业出版社,2005
[23]刘大杰,全球定位系统(GPS)的原理与数据处理[M],同济大学出版社,2001
[24]熊小莉,直接序列扩频信号数字科斯塔斯环的分析与设计[J],电讯技术,2001(4)
[25]王诚 吴继华 范丽珍等,Altera FPGA/CPLD设计[M],北京:人民邮电出版社,2005,1-23
[26]李洪伟 袁斯华,基于Quartus Ⅱ的FPGA/CPLD设计fMl,北京:电子工业出版社,2006
[27]任爱峰 初秀芹,基于FPGA的嵌入式系统设计[M],西安:西安电子科技大学出版社,2004
[28]Altera,Cyclone Device Handbook[Z],http://www.altera.com,1994
[29]潘松 黄继业,EDA技术实用教程[M],北京:科学出版社2002,10-38
[30]Paulo S.R.Diniz Eduardo A.B.da Silva Sergio L.Netto,数字信号处理系统分析与设计[M]. (门爱东等译),北京:电子工业出版社,2004
[31]胡广书,数字信号处理—理论、算法与实现[M],北京:清华大学出版社,2003
[32]张欣,扩频通信数字基带信号处理算法及其VLSI实现[M],北京:科学出版社,2004
[33]程佩青,数字滤波与快速傅立叶变换[M],北京:清华大学出版社,1990
[34]Emmanuel C.Ifeachor Barrie W.Jervis.,数字信号处理实践方法[M](罗鹏飞等译),北京:电子工业出版社,2004
[35]Uwe Meyer-Baese,数字信号处理的FPGA实现(第二版)[M](刘凌,胡永生译),北京:清华大学出版社,2006
[36]Coenen AVan Nee D.Novel,Fast GPS/GLONSS Code Acquisition[J].Electronics Letters,1992,28(9)
[37]王运盛,基于DSP的GPS/DR组合导航系统设计[D],硕士学位论文,武汉大学,2004
[38]Gunawardena S.Feasibility,Study for the Implementation of Global Positioning System Block Processing Techniques in Field Programmable Gate Arrays[D].Ohio University,2000.
[39]Cohn M.Lemple A.On Fast M-Sequence Transforms[J]IEEE Transactions on Information Theory 1997
[40]ICD-GPS-200:Interface Control Document[Z],USA,ARINC Research,1997.
[41]赵明忠,基于FPGA技术的数字相关器的设计与实现[J],电子应用技术,2002(28)
[42]孙学军 王秉均,通信原理[M],北京:电子工业出版社,2001
[43]安效君 王力男,NCO的数字化实现及应用[J],无线电通信技术,2004(30)
[44]齐洪喜 陆颖,VHDL电路设计实用教程[M1,北京:清华大学出版社,2004
[45]A.J维特比,CDMA扩频通信原理(李世鹤 鲍刚 彭容译)[M],北京:人民邮电出版社,1997
[46]庞浩 王赞草,一种基于FPGA实现的全数字锁相环[J],电子技术应用,2005(5)
[47]阿兰.布兰查德,锁相环及其在相干接收机设计中的应用(向永正 曹献枕译)[M],北京:人民邮电出版社,1980
[48]Alaqeeli A.,Global Positioning System Signal Acquisition and Tracking Using Field Programmable Gate Arrays[D].Ohio University,2002
[49]李洪涛,GPS应用程序设计[M],北京:科学出版社,1999
[50]Mattos Philip G.Intergraded GPS and Dead Reckoning for low-cost vehicle navigation and tracking[J]IEEE Transactions on Automatic Control,1995