Ftt makes the frequency sampled at a same frequency interval on unit circle , and the frequency interval limits the practical range - precision of the radar , and makes range precision at an equivalent level with range - resolution 由于fft的实质是频率在单位圆上的等间隔采样,其采样间隔限制了雷达的实际测距精度,使得其测距精度与其距离分辨力处于同一量级。
In hf ( high frequency ) radar , the targets detected based on the spectrum processed by the two - dimension fft are peak - like , which makes the operator distinguish them from the clutter and background noise easiler in the 3d ( three - dimension ) display than the 2d 特别对于距离分辨力低的高频雷达系统,其探测的目标通常近似为点目标,在经二维傅立叶变换得到的频谱数据上呈现峰状结构。
Pulse compression technique and large timeband product signals such as linear frequency modulation signals , nolinear frequency modulation signals , phase coded signals and so on are widely used in modern radar systems to improve the resolving power both in range and in speed domain 现代雷达为了提高雷达作用距离和速度分辨力、距离分辨力，广泛采用了脉冲压缩技术及大时宽带脉压信号如：线形调频、非线形调频、相位编码信号等。
To improve this ability , a higher cross - range resolution is needed . an inverse synthetic aperture radar ( isar ) achieves high resolution in the cross - range dimension by taking advantage of the motion between radar and targets to synthesize the effect of a larger antenna aperture 逆合成孔径雷达( inversesyntheticapertureradar ,简称isar )信号处理对接收到的运动目标的回波信号进行相干处理,等价成一个大口径天线,很大程度上提高了方位向距离分辨力。
Pulse compression technique is widely used in modern radar systems . it solves the contradiction between the range and velocity resolution . large time - bandwidth product signals such as linear frequency modulation signals ( lfm ) are used in pulse compression technique to improve the resolution in range domain 现代雷达系统广泛采用脉冲压缩技术,在确保雷达作用距离和速度分辨力的前提下,采用大时带积脉冲压缩信号:如线性调频( lfm )信号提高距离分辨力。
In the early years , beam former is mainly designed in narrow band , and applied in radar , communication etc . however , in signal processing , many broadband signals will be processed , for instance : earthquake signal , sound signal or sonar signal 早期的波束形成器是以窄带为主的，主要应用在雷达、通信等方面。但在阵列信号处理中，也会遇到许多宽带信号处理的问题，如对地震信号、语音信号以及声纳信号的处理，另外，雷达为了获得高距离分辨力和获取目标更多的特征也要求使用宽带信号。
First , this dissertation analyses the waveform of chirp - subpulse stepped frequency signal , studies and simulates the ambiguity characteristics , the spectrum structure and the basic process to obtain high resolution range profiles , and discuss this signal ’ s high range resolution characteristic and wide spectrum characteristic 首先,本文对chirp子脉冲频率步进信号进行了波形分析,研究了chirp子脉冲频率步进信号的模糊特性、频谱结构以及合成高分辨距离像的基本过程,讨论了chirp子脉冲频率步进信号的高距离分辨力和宽带频谱特性。
This paper gives a detailed account of the waveform , matched - filter , fuzzy function , resolution in speed , resolution in range and the capacity of anti - interference of the chirp signal . it deals with several methods to produce chirp signal and the advantages and disadvantages of these methods . it describes the working principle and performance of dds , analyses the phase errors initiated by the phase truncation and proposes a new scheme to solve the error 本文详细介绍了以下几个方面：线性调频信号的波形、匹配滤波器、模糊函数、速度分辨力、距离分辨力及抗干扰能力；产生线性调频信号的几种方法并简要分析了各种方法的优缺点； dds的工作原理、性能指标，分析了相位截断产生的相位误差，并提出解决这种误差的新方案；设计了一个产生线性调频信号的具体电路。
Pulse compression technique is widely used in modern radar systems . large timeband product signals such as linear frequency modulation signals ( lfm ) , nonlinear frequency modulation signals ( nlfm ) , phase coded signals and so on are used in pulse compression technique to improve the resolution in range domain 现代雷达系统广泛采用脉冲压缩技术,在确保雷达作用距离和速度分辨力的前提下,采用大时带积脉冲压缩信号:如线性调频( lfm ) 、非线性调频( nlfm )和相位编码信号等,提高距离分辨力。
In this thesis , based on this kind of application , we made theoretical analysis and engineering practice on high - precision lfmcw and its signal processing millimeter wave broadband lfmcw radar has quite high theoretical range - precision and distance resolution , however , for the real radar system , the nonideal parameter of its transmitting signal , such as power fluctuation and the nonlinearity in frequency sweep , will result in the decreasing of the practical rang - precision and the distance resolution of radar 本文基于这一应用对高精度lfmcw测距雷达及其信号处理进行了理论分析和工程实践。毫米波宽带lfmcw雷达具有很高的理论测距精度和距离分辨力,但对于实际的雷达系统,其发射信号的非理想参数-扫频功率起伏和扫频非线性,将使得雷达的实际测距精度和距离分辨力下降。
