基于LFMCW的车流量监测雷达设计

发布时间：2018-06-13 07:02

本文选题：线性调频连续波 + 车流量监测雷达　；参考：《西安电子科技大学》2015年硕士论文

【摘要】：随着人们生活水平的不断提高,城市中各种车辆的数量正在急剧增加,这就对其交通监测和管理系统的建设提出了更高的要求。在此背景下,一些新的发展理念如“智能交通系统(ITS)”、“智能城市(SC)”等已被提出,并成为许多大、中型城市的发展目标。作为ITS建设的重要组成部分,准确、可靠的车流量监测设备将面临广泛的需求。因此,具有高精度、高可靠性和易于维护等优点的线性调频连续波(LFMCW)雷达在车流量监测方面具有广阔的发展和应用前景。本车流量监测雷达主要用于完成4至8车道车流量的监测,主要包括:三角波发生电路、连续波雷达传感器、中频信号处理电路和数字信号处理模块等。三角波发生电路由MAX038芯片及其外围电路构成,所产生的频率可调、幅度相对恒定的三角波对连续波雷达传感器中的压控振荡器(VCO)进行控制,使其向特定区域发射LFMCW信号。连续波雷达传感器是车流量监测雷达的射频部分,主要用于发射高频线性调频连续波信号,并将其与车辆反射的回波进行混频、放大等处理后输出包含车辆距离信息的中频信号。中频信号处理电路的设计是实现车辆检测的重要基础,主要由高通滤波器、低通滤波器和中频放大电路等组成。其中,高通滤波器用于滤除频率调制过程中的三角波泄漏,并利用其过渡带的放大特性减小中频信号的动态范围;低通滤波器用于滤除带外噪声和高频干扰,进一步提高中频信号的质量;中频放大电路用于对经过滤波的微弱中频信号进行放大。数字信号处理模块是本车流量监测雷达设计的核心,主要由两部分组成:FPGA芯片EP2S90F1020与DSP芯片TMS320C6727B及其外围电路组成的硬件部分和在此基础上完成的算法设计部分。其中,FPGA部分用于对中频信号进行模数转换、时域杂波背景消除等处理,并将结果传输至DSP;DSP在对数字中频信号完成FFT、自适应门限检测、梳状带通滤波等处理的基础上实现车辆检测和车流量统计等功能。测试结果表明本车流量监测雷达稳定、可靠,具备实现车流量监测的基本功能。
[Abstract]:With the continuous improvement of people's living standards, the number of vehicles in cities is increasing rapidly, which puts forward higher requirements for the construction of traffic monitoring and management system. In this context, some new development concepts such as "Intelligent Transportation system (ITS)" and "Intelligent City (SCS)" have been put forward and become the development goals of many large and medium-sized cities. As an important part of its construction, accurate and reliable vehicle flow monitoring equipment will face extensive demand. Therefore, the linear frequency modulation continuous wave (LFMCW) radar, which has the advantages of high precision, high reliability and easy maintenance, has a broad prospect of development and application in traffic flow monitoring. The vehicle flow monitoring radar is mainly used to monitor the traffic flow of 4 to 8 lanes, including: triangular wave generating circuit, continuous wave radar sensor, if signal processing circuit and digital signal processing module. The triangle-wave generating circuit is composed of MAX038 chip and its peripheral circuit. The frequency of the triangulation wave is adjustable and the amplitude is relatively constant to control the voltage-controlled oscillator (VCO) in the continuous wave radar sensor, which emits LFMCW signal to a specific area. Continuous wave radar sensor is the radio frequency part of vehicle flow monitoring radar. It is mainly used to transmit high frequency linear frequency modulated continuous wave signal and mix it with the echo reflected by vehicle. An intermediate frequency signal containing vehicle distance information is output after processing such as amplification. The design of intermediate frequency signal processing circuit is an important basis for vehicle detection, which consists of high pass filter, low pass filter and if amplifier circuit. The high-pass filter is used to filter the triangular wave leakage in the frequency modulation process, and the dynamic range of the intermediate frequency signal is reduced by using the amplification characteristic of the transition band, while the low-pass filter is used to filter the out-of-band noise and the high-frequency interference. The if amplifier circuit is used to amplify the filtered weak if signal. The digital signal processing module is the core of the design of the vehicle flow monitoring radar. It mainly consists of two parts: the hardware part of EP2S90F1020 and DSP chip TMS320C6727B and its peripheral circuit, and the algorithm design part based on this. The FPGA is used to process the if signal such as A / D conversion, time domain clutter background cancellation and so on. The result is transmitted to DSP to complete FFTand adaptive threshold detection for digital if signal. On the basis of comb band-pass filtering and other processing, the functions of vehicle detection and traffic flow statistics are realized. The test results show that the vehicle flow monitoring radar is stable, reliable and has the basic function of vehicle flow monitoring.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U495;TN959

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