基于零中频的FMCW测距雷达设计

发布时间：2018-04-30 02:13

本文选题：FMCW测距雷达 + 零中频接收机　；参考：《大连海事大学》2017年硕士论文

【摘要】：雷达最基本的功能就是距离测量,测距雷达普遍应用于物位距离的测量。随着科技的发展,对物位雷达的精度、体积、功耗等要求也越来越高。小型测距雷达已成为当前的研究热点。FMCW雷达发射的信号为连续波信号,具有较宽的频带带宽,相对于脉冲雷达来说发射功率更小。综上所述本文设计了一款小型化短程零中频FMCW测距雷达系统。FMCW体制雷达常用的接收机为超外差式接收机,针对超外差式接收机集成难度高、体积大、成本高等问题,本文利用零中频技术与FMCW体制雷达相结合,设计了一款测距雷达。此外,针对DSP、单片机等雷达常用数据采集处理方式无法实时处理信号的问题,本文提出利用电脑声卡作为传输通道,使信号传输、采集、处理更加便捷、灵活。整个设计分为收发信机部分,天线部分以及数据采集与处理三个部分。收发信机部分分为发射部分与接收部分。首先,发射部分针对压控振荡器线性度问题,设计一款幅度、周期可调的锯齿波发生器。其次,接收部分针对零中频固有的本振泄露与直流偏置、I/Q失衡等问题,利用一款端口隔离度为50dB,片内集成90°移相器的混频器来解决。然后,针对本雷达的工作频段,发射带宽等参数的匹配问题,利用HFSS13.0,设计一款定向小型化对数周期天线。该类型天线相较于宽频带阵列、层叠天线来说,体积小、易于加工。最后,本文利用16位的采样频率为22.05KHz的声卡作为模数转换器,设计了一套信号采集系统,提高了信号采集处理的便捷度与灵活度。利用Matlab内置的FFT算法对采集到的信号进行处理,从而得到相应的距离信息。将不同距离下的信号进行分段处理,引入修正因子概念,修正距离信息来提高精度。加工后实测具体参数为:尺寸5.6cm*7.6cm,发射扫频带宽702.5MHz,发射功率+7dBm,噪声系数2.79,灵敏度-83dBm。对数周期天线具体参数为:尺寸3.1cm*2.6cm,工作频段为 5.155～6.455GHz,增益为+7dB。
[Abstract]:The most basic function of radar is range measurement. Ranging radar is widely used to measure the distance of object level. With the development of science and technology, the precision, volume and power consumption of object level radar are becoming higher and higher. The signal transmitted by FMCW radar is a continuous-wave signal with a wide bandwidth and a smaller power than that of a pulse radar. To sum up, this paper designs a miniaturized short-range zero-intermediate frequency FMCW ranging radar system. The usual receiver of FMCW radar system is superheterodyne receiver, aiming at the problems of high integration difficulty, large volume and high cost of superheterodyne receiver. In this paper, a ranging radar is designed by combining zero intermediate frequency technology with FMCW system radar. In addition, aiming at the problem that the common data acquisition and processing methods such as DSP and SCM can not process signals in real time, this paper puts forward the use of computer sound card as the transmission channel to make the signal transmission, acquisition and processing more convenient and flexible. The whole design is divided into three parts: transceiver, antenna and data acquisition and processing. The transceiver is divided into a transmitting part and a receiving part. First of all, aiming at the linearity of VCO, a sawtooth wave generator with adjustable amplitude and period is designed. Secondly, in order to solve the problems of zero-intermediate frequency inherent leakage of local oscillator and the imbalance of DC bias I / Q, the receiver uses a mixer with 50 dB port isolation and an in-chip 90 掳phase shifter to solve the problem. Then, aiming at the matching problem of the operating frequency band and transmitting bandwidth of this radar, a directional miniaturized logarithmic periodic antenna is designed by using HFSS 13.0. Compared with broadband arrays, this type of antenna is compact and easy to process. Finally, a signal acquisition system is designed by using a 16-bit sound card with a sampling frequency of 22.05KHz as an analog-to-digital converter, which improves the convenience and flexibility of signal acquisition and processing. The acquired signal is processed by the FFT algorithm built in Matlab, and the corresponding distance information is obtained. The signal at different distances is segmented, the concept of correction factor is introduced, and the range information is corrected to improve the accuracy. The measured parameters are as follows: the dimension is 5.6 cm ~ (-1) 7.6cm, the frequency sweep bandwidth is 702.5 MHz, the emission power is 7dBm, the noise coefficient is 2.79, and the sensitivity is -83 dBm. The specific parameters of the logarithmic periodic antenna are as follows: the size is 3.1 cm ~ (-1) 2.6cm, the working frequency band is 5.155 ~ 6.455GHz, and the gain is 7 dB.
【学位授予单位】：大连海事大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN959

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