FFT-CZT技术在单天线LFMCW无线电高度表中的应用  

The FFT-CZT algorithm' s application in single-antenna LFMCW radio altimeters

作　　者：曾国奇[1] 李思吟[2] 王松[1] 齐电海[1] 饶赣新 

机构地区：[1]北京航空航天大学无人机驾驶飞行器设计研究所,北京100191 [2]北京航空航天大学电子信息工程学院,北京100191 [3]贵航飞机设计研究所科技开发部,安顺561000

出　　处：《高技术通讯》2013年第3期308-312,共5页Chinese High Technology Letters

基　　金：863计划(2008AA121802);航空基金(2009ZC51026)资助项目

摘　　要：设计了单天线线性调频连续波(LFMCW)无线电高度表系统,该系统采用矢量对消技术抵消来自环形器泄漏和天线驻波反射的信号。采用快速傅立叶变换(FFT)与线性调频Z变换(CZT)相结合的技术(称为FFT-CZT技术)对发射信号和回波信号混频后的中频信号进行频谱分析(先用FFT技术进行频谱粗分析,再用CZT技术进行频谱细分析),以解决频率分辨率与计算时间的矛盾,提高系统的测量精度和抗干扰能力。仿真分析了单天线LFMCW无线电高度表系统的工作过程。仿真分析结果表明:将FFT-CZT技术应用于单天线LFMCW无线电高度表中是可行的;与传统的模拟体制相比,系统的测量精度和抗干扰能力明显提高,系统可应用于除零高度以外的高度测量中。A LFMCW （ linear frequency modulated continuous wave） radio altimeter system with a single antenna was established, which is characterized by using the vector cancellation technology to cancel the RF signal coming from the circulator＇ s leaking and the reflection of the antenna＇ s stationary waves. The technique of combining the fast Fourier transform （FFT） with the chirp Z-translation, called the FFT-CZT technique for short, was used to analyze the IF signal created by mixing emission signal with echo signal （Firstly the FFT algorithm was adopted to analyze signals＇ spectra coarsely, and then the CZT algorithm was used to analyze signals＇ spectra precisely） to solve the conflict of frequency resolution and calculation time and improve the system＇ s anti-interference ability and measurement accura- cy. The working procedure of the single-antenna LFMCW radio altimeter system was simulated, and the simulation resuits show that the application of the FFT-CZT algorithm to single-antenna LFMCW radio altimeters is feasible. The system can be used in height measurement except in the zero altitude instance. And compared with the traditional analog system, the measurement accuracy and the anti-interference ability of the system are improved obviously.

关 键 词：线性调频连续波(LFMCW) 无线电高度表 单天线 FFT-CZT 矢量对消器 

分 类 号：TN925[电子电信—通信与信息系统]