应答式厘米波汽车防撞雷达的研究
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摘要
本文以现有技术的可实现性为出发点，讨论了汽车防撞雷达的性能要求、工作原理和总体设计等相关问题，总结了国内外汽车防撞雷达的研发状况，在此基础上设计了一种应用于高速公路上的应答式厘米波汽车防撞预警雷达。
工作频段和工作体制是防撞雷达系统设计的两个主要问题。一般认为，汽车防撞雷达应同时具有测距、测速和测角三种功能。通行的汽车防撞雷达采用了波长短、测量精度高的毫米波，以调频连续波制式测量距离和速度，以多波束扫描的方式测量角度。这种防撞雷达对器件性能要求高，技术复杂，工程实现难度大。考虑到：（1）核心的测距功能实现以后，雷达已经能够完成基本的防撞预警；（2）在汽车高速运行的情况下，防撞雷达的最小可测距范围和最大作用距离应比低速状态下大。本文采用了技术成熟，易于工程实现的厘米波脉冲雷达，以单波束辐射的方式测距。为了弥补厘米波波束大、作用距离不如毫米波的缺点，系统在目标车辆的尾部增加了一级转发器，以双机应答的方式测量车距。
雷达对目标回波的检测能力是雷达测距性能的基础。雷达在噪声背景中检测信号是一个概率问题，提高雷达的检测能力可归结为如下两个途径：（1）在信噪比一定的情况下，选择一最佳门限，使其在一定风险准则下错误判决产生的“代价”最小。（2）提高回波信号的信噪比，从根本上减小错误判决的概率。本文推导了最佳门限电平的表达式和脉冲积累对回波信号信噪比的改善能力。并设计了先对回波信号进行高速采样然后同步累加进行脉冲积累的方案。
本文结合大量的框图、电路图、波形图，详细阐述了改进后的应答式厘米波汽车防撞预警雷达的体系结构、工作原理、工作流程。并根据信号的工作频段，将整机系统分为射频信道、中频调制解调和终端处理三大部分。在射频部分讨论了系统设计的参数选择问题；在中频部分设计实现了雷达脉冲和中频载波的产生以及矩形脉冲调幅和解调电路；在终端处理部分设计实现了A/D采样、脉冲积累、距离计算以及距离显示译码电路。除A/D采样以外，终端部分的全部电路均在FPGA中实现。
Focused on the realization in engineering practice, this paper discussed automotive anticollision radar's function requirement, working principle and system design. Through summarizing and analysis of its research and development, the paper proposes a new type of secondary centimeter wave automotive anticollision radar that applied on the expressway.
Carrier frequency and modulation scheme are two key issues in the system design of automotive anticollision radar. Popular automotive anticollision radar is required to measure the velocity and angle of its targets as well as range. Therefore, the short-wavelength high-resolution millimeter wave is used, measuring range and velocity through FMCW scheme, measuring angle through multi-beam scanning. However, this type of radar demands complex technologies and components of excellent performance, hence difficult to realize in applications. Considering that: (1) radar can achieve its basic application of collision avoidance and warning with the only function of ranging; (2) under high speed conditions, radar should have lager effective range than that under slow speed, we designed a new easily realizable automotive anticollision radar, which employs centimeter wave and square pulse amplitude modulation. To compensate centimeter wave's shorting comings such as broad beam and short effective range, a transponder is added in the back of target automotive. This secondary radar measures range in the way of transponding.
The ranging performance of radar is based on its performance of echo detection. Detecting echo in the background of noise is a probability problem. There are two ways to enhance the radar's detection performance: (1) for certain signal to noise ratio, choose a optimum detection threshold, whose false decisions producing minimum cost under the preset cost rules; (2) basically reduce the false decision probability by increasing echo's SNR. This paper deduces the optimum threshold expression under certain cost rule and relationship between the number of pulse accumulation and the increased ratio of echo's SNR. The according pulse accumulation method is designed and realized, i.e. digitalizing the echo and synchronously accumulating them in RAM.
With the illustrations of many block diagrams, circuit schematics and waveform
figures, this paper expatiates the system architecture, working principle and working flow of the revised secondary Cm-wave automotive anticollision radar. The whole system is divided into three parts according to the signal frequency, i.e., RF channel, IF modulation and demodulation, digital terminal. Part 1 discusses system design and parameter selection. Part 2 puts forward the circuits of pulse and IF carrier generation and square pulse amplitude modulation and demodulation. The final part brings the circuits of digitalization, pulse accumulation, range calculation and decoding of range display. All the circuits in digital terminal module are designed in FPGA.
工作频段和工作体制是防撞雷达系统设计的两个主要问题。一般认为，汽车防撞雷达应同时具有测距、测速和测角三种功能。通行的汽车防撞雷达采用了波长短、测量精度高的毫米波，以调频连续波制式测量距离和速度，以多波束扫描的方式测量角度。这种防撞雷达对器件性能要求高，技术复杂，工程实现难度大。考虑到：（1）核心的测距功能实现以后，雷达已经能够完成基本的防撞预警；（2）在汽车高速运行的情况下，防撞雷达的最小可测距范围和最大作用距离应比低速状态下大。本文采用了技术成熟，易于工程实现的厘米波脉冲雷达，以单波束辐射的方式测距。为了弥补厘米波波束大、作用距离不如毫米波的缺点，系统在目标车辆的尾部增加了一级转发器，以双机应答的方式测量车距。
雷达对目标回波的检测能力是雷达测距性能的基础。雷达在噪声背景中检测信号是一个概率问题，提高雷达的检测能力可归结为如下两个途径：（1）在信噪比一定的情况下，选择一最佳门限，使其在一定风险准则下错误判决产生的“代价”最小。（2）提高回波信号的信噪比，从根本上减小错误判决的概率。本文推导了最佳门限电平的表达式和脉冲积累对回波信号信噪比的改善能力。并设计了先对回波信号进行高速采样然后同步累加进行脉冲积累的方案。
本文结合大量的框图、电路图、波形图，详细阐述了改进后的应答式厘米波汽车防撞预警雷达的体系结构、工作原理、工作流程。并根据信号的工作频段，将整机系统分为射频信道、中频调制解调和终端处理三大部分。在射频部分讨论了系统设计的参数选择问题；在中频部分设计实现了雷达脉冲和中频载波的产生以及矩形脉冲调幅和解调电路；在终端处理部分设计实现了A/D采样、脉冲积累、距离计算以及距离显示译码电路。除A/D采样以外，终端部分的全部电路均在FPGA中实现。
Focused on the realization in engineering practice, this paper discussed automotive anticollision radar's function requirement, working principle and system design. Through summarizing and analysis of its research and development, the paper proposes a new type of secondary centimeter wave automotive anticollision radar that applied on the expressway.
Carrier frequency and modulation scheme are two key issues in the system design of automotive anticollision radar. Popular automotive anticollision radar is required to measure the velocity and angle of its targets as well as range. Therefore, the short-wavelength high-resolution millimeter wave is used, measuring range and velocity through FMCW scheme, measuring angle through multi-beam scanning. However, this type of radar demands complex technologies and components of excellent performance, hence difficult to realize in applications. Considering that: (1) radar can achieve its basic application of collision avoidance and warning with the only function of ranging; (2) under high speed conditions, radar should have lager effective range than that under slow speed, we designed a new easily realizable automotive anticollision radar, which employs centimeter wave and square pulse amplitude modulation. To compensate centimeter wave's shorting comings such as broad beam and short effective range, a transponder is added in the back of target automotive. This secondary radar measures range in the way of transponding.
The ranging performance of radar is based on its performance of echo detection. Detecting echo in the background of noise is a probability problem. There are two ways to enhance the radar's detection performance: (1) for certain signal to noise ratio, choose a optimum detection threshold, whose false decisions producing minimum cost under the preset cost rules; (2) basically reduce the false decision probability by increasing echo's SNR. This paper deduces the optimum threshold expression under certain cost rule and relationship between the number of pulse accumulation and the increased ratio of echo's SNR. The according pulse accumulation method is designed and realized, i.e. digitalizing the echo and synchronously accumulating them in RAM.
With the illustrations of many block diagrams, circuit schematics and waveform
figures, this paper expatiates the system architecture, working principle and working flow of the revised secondary Cm-wave automotive anticollision radar. The whole system is divided into three parts according to the signal frequency, i.e., RF channel, IF modulation and demodulation, digital terminal. Part 1 discusses system design and parameter selection. Part 2 puts forward the circuits of pulse and IF carrier generation and square pulse amplitude modulation and demodulation. The final part brings the circuits of digitalization, pulse accumulation, range calculation and decoding of range display. All the circuits in digital terminal module are designed in FPGA.
引文
[1] 丁鹭飞，耿富录. 雷达原理. 西安电子科技大学出版社, 2002年
[2] M.I 斯科尔尼克（著），谢卓（译）. 雷达手册. 国防工业出版社, 1978年6月
[3] Roy Blake. Electronic and Communication Systems. 电子工业出版社, 2002年
[4] 管致中，夏恭恪. 信号与线性系统 高等教育出版社 1992年
[5] 张建辉. 毫米波汽车防撞雷达的研究. 南京理工大学博士论文，2001年7月
[6] 张建辉，刘国岁，顾红，苏卫民. 编码步进调频连续波信号在汽车防撞雷达中的应用. 电子学报, 2001年第7期
[7] 徐淑正. 基于DSP的汽车防撞雷达信号的产生与采集. 山东大学硕士学位论文, 2000年12月
[8] 盛怀茂，夏冠群.等. FMCW毫米波防撞雷达系统. 汽车电子，2001年第2期
[9] 程震先，恽雪如. 汽车防撞雷达的数据处理. 北京理工大学学报 1995年5月
[10] 朱红卫，刘爱琴，曾迎生. 一种用于车辆自主导航的传感器系统. 高技术通讯, 1995年第2期
[11] 梁德文 世纪之交的军民两用毫米波技术. 电讯技术, 1999年第6期
[12] 程晓佩等译，汽车防撞雷达用宽扫瞄角反射体的分析与设计. 电子工程, 2000年2月
[13] Klotz, Rohling, A high range resolution radar system for parking aid applications,
5th Intern. Conference on Radar Systems, Brest, France, May 1999;
[14] Klotz, H. Rohling; 24GHz Radar Sensors for Automotive Applications 5th International Conference on Radar Systems, Brest, France, May 1999;
[15] R. Doerfler, W. Hosp, M. Kunert; Development of automotive radar applications in Siemens AT - an example for modern development processes 6th International Conference ATA, Florence, 1999;
[16] A. Hoess et al., RadarNet Conference eMobility, Gothenburg, Sweden, May 2001
[17] A. Hoess et al., Design and realization of a novel, synchronized 77 GHz radar network for automotive use 2002 IMS Workshop on circuit and antenna technologies for automotive radars, Seattle, USA, June 3, 2002
[18] H.-J. Siweris; Semiconductor solutions for low cost millimeter-wave automotive radar frontends 2002 IMS Workshop on circuit and antenna technologies for automotive radars, Seattle, USA, June 3, 2002
[19] William David; FMCW MMW Radar for Automotive Longitudinal Control, California PATH Research Report, May 1997
[20] 卢毅，赖杰. VHDL与数字电路设计. 科学出版社, 2001年
[21] 褚振永， 翁木云. FPGA设计及应用. 西安电子科技大学出版社, 2002年7月
[22] 侯伯亨, 顾新. VHDL硬件描述语言与数字逻辑电路设计. 西安电子科技大学出版社, 1999年
[23] 牛田佳，无线电爱好者读本. 人民邮电出版社, 1996年2月
[22] Maxim Integrated Products, MAX1448 Data Sheet; http://maxim-ic.com
[24] Altera Corporation, ACEX 1K PLD Family Data Sheet; http://altera.com
[25] Motorala Corporation. Retriggerable Monostable Multivibrators http://motorala.com
[26] P.M. Woodward, MA Probablilty and information theory, with application to radar Pergamon Press Ltd. 1953
[27] 杨士中，截获接收机频率分析器在噪声作用下的性能分析. 电子学报，1980年第4期
[28] Willis H. Harman. Principles of the Statistical theory of Communication McGraw-Hill Book Company, Inc. 1963年
[29] 王毓银. 脉冲与数字电路. 高等教育出版社. 1997年
[30] 重庆大学高等数学教研室. 高等数学. 重庆大学出版社. 1997年
[2] M.I 斯科尔尼克（著），谢卓（译）. 雷达手册. 国防工业出版社, 1978年6月
[3] Roy Blake. Electronic and Communication Systems. 电子工业出版社, 2002年
[4] 管致中，夏恭恪. 信号与线性系统 高等教育出版社 1992年
[5] 张建辉. 毫米波汽车防撞雷达的研究. 南京理工大学博士论文，2001年7月
[6] 张建辉，刘国岁，顾红，苏卫民. 编码步进调频连续波信号在汽车防撞雷达中的应用. 电子学报, 2001年第7期
[7] 徐淑正. 基于DSP的汽车防撞雷达信号的产生与采集. 山东大学硕士学位论文, 2000年12月
[8] 盛怀茂，夏冠群.等. FMCW毫米波防撞雷达系统. 汽车电子，2001年第2期
[9] 程震先，恽雪如. 汽车防撞雷达的数据处理. 北京理工大学学报 1995年5月
[10] 朱红卫，刘爱琴，曾迎生. 一种用于车辆自主导航的传感器系统. 高技术通讯, 1995年第2期
[11] 梁德文 世纪之交的军民两用毫米波技术. 电讯技术, 1999年第6期
[12] 程晓佩等译，汽车防撞雷达用宽扫瞄角反射体的分析与设计. 电子工程, 2000年2月
[13] Klotz, Rohling, A high range resolution radar system for parking aid applications,
5th Intern. Conference on Radar Systems, Brest, France, May 1999;
[14] Klotz, H. Rohling; 24GHz Radar Sensors for Automotive Applications 5th International Conference on Radar Systems, Brest, France, May 1999;
[15] R. Doerfler, W. Hosp, M. Kunert; Development of automotive radar applications in Siemens AT - an example for modern development processes 6th International Conference ATA, Florence, 1999;
[16] A. Hoess et al., RadarNet Conference eMobility, Gothenburg, Sweden, May 2001
[17] A. Hoess et al., Design and realization of a novel, synchronized 77 GHz radar network for automotive use 2002 IMS Workshop on circuit and antenna technologies for automotive radars, Seattle, USA, June 3, 2002
[18] H.-J. Siweris; Semiconductor solutions for low cost millimeter-wave automotive radar frontends 2002 IMS Workshop on circuit and antenna technologies for automotive radars, Seattle, USA, June 3, 2002
[19] William David; FMCW MMW Radar for Automotive Longitudinal Control, California PATH Research Report, May 1997
[20] 卢毅，赖杰. VHDL与数字电路设计. 科学出版社, 2001年
[21] 褚振永， 翁木云. FPGA设计及应用. 西安电子科技大学出版社, 2002年7月
[22] 侯伯亨, 顾新. VHDL硬件描述语言与数字逻辑电路设计. 西安电子科技大学出版社, 1999年
[23] 牛田佳，无线电爱好者读本. 人民邮电出版社, 1996年2月
[22] Maxim Integrated Products, MAX1448 Data Sheet; http://maxim-ic.com
[24] Altera Corporation, ACEX 1K PLD Family Data Sheet; http://altera.com
[25] Motorala Corporation. Retriggerable Monostable Multivibrators http://motorala.com
[26] P.M. Woodward, MA Probablilty and information theory, with application to radar Pergamon Press Ltd. 1953
[27] 杨士中，截获接收机频率分析器在噪声作用下的性能分析. 电子学报，1980年第4期
[28] Willis H. Harman. Principles of the Statistical theory of Communication McGraw-Hill Book Company, Inc. 1963年
[29] 王毓银. 脉冲与数字电路. 高等教育出版社. 1997年
[30] 重庆大学高等数学教研室. 高等数学. 重庆大学出版社. 1997年