FMCW雷达的发射泄漏及相位噪声的抑制

发布时间：2018-05-28 07:25

本文选题：线性调频连续波雷达 + 泄漏　；参考：《电子科技大学》2014年硕士论文

【摘要】：调频连续波(FMCW)雷达具有低成本和低功耗等特点,在海军战术导航、雷达智能弹药传感器和汽车雷达等不同领域获得广泛应用。而且,具有单基结构的雷达,其发射机和接收机同时使用一个天线,这将使系统更紧凑。在设计单天线FMCW雷达的最大挑战之一是在发射机和接收机之间有足够的隔离度。在脉冲雷达,这很容易通过时间选通来实现。在连续波雷达,发射和接收是同时进行的,而且要从环行器的泄漏信号和天线失配的反射信号中检测皮瓦量级、甚至更低的目标回波。这会导致两个严重的问题,其中一个问题是发射机噪声边带会淹没有用的目标。另外一个问题是发射机功率泄漏到接收机,降低了接收机的灵敏度。泄漏到接收机的发射功率的相位噪声会落入同一频带的雷达视频信号,而且不能滤波出来。因而,常规的FMCW雷达的动态范围是有限的。本文围绕发射泄漏进行了分析和研究,包括泄漏原理和反射功率对消技术。在此基础上,提出了一种改进的方案,即自适应对消系统。完成的具体工作如下:本文首先介绍了FMCW相关知识,包括FMCW雷达的优缺点,FMCW雷达的一些应用以及FMCW雷达的工作原理。在此基础上,做了MATLAB仿真,包括连续信号和四个目标回波。针对发射泄漏问题,进行了深入的分析,包括信号泄漏的途径,天线反射原理和天线反射回波功率,并分析了泄漏噪声对接收机性能的影响。其次分析了反射功率对消器(RPC)技术方案,包括模拟对消方案和数字对消方案。在此基础上,分析了这两种方案的优缺点。同时,对反射功率器的对消性能进行了分析和研究,包括对消深度,对消宽带和对消性能的评价。最后提出了改进方案,采用自适应对消结构和LMS算法。在此基础上,先介绍了LMS算法,从理论上研究了自适应对消系统结构,并进一步分析了系统的加权系数、输出信干比(系统输出的泄漏信号和噪声的比值)以及信噪比。同时,在MATLAB上对系统进行仿真,包括只有泄漏信号的系统仿真,含有噪声的系统仿真,含有目标的系统仿真,含有两个泄漏信号的系统仿真,本振信号含有噪声的系统仿真和含有三个目标信号的系统仿真。另外,研究了步长对系统的影响,并做了仿真。
[Abstract]:FMCW (Frequency modulated continuous Wave) radar has been widely used in various fields such as naval tactical navigation radar intelligent ammunition sensor and automobile radar because of its low cost and low power consumption. Moreover, a radar with a single-base structure with a transmitter and receiver using an antenna will make the system more compact. One of the biggest challenges in designing a single antenna FMCW radar is enough isolation between the transmitter and the receiver. In pulsed radar, this is easily achieved by time switching. In continuous-wave radar, the transmitter and receiver are simultaneously transmitted and received, and the Piwa order of magnitude or even lower target echo is detected from the leaky signal of the circulator and the mismatched reflection signal of the antenna. This can lead to two serious problems, one of which is that the transmitter noise sideband submerges useful targets. Another problem is the transmitter power leakage to the receiver, reducing the sensitivity of the receiver. The phase noise leakage to the receiver will fall into the same frequency band radar video signal and can not be filtered out. Therefore, the dynamic range of conventional FMCW radar is limited. This paper focuses on the analysis and research of emission leakage, including leakage principle and reflection power cancellation technology. On this basis, an improved scheme, adaptive cancellation system, is proposed. The main contents of this paper are as follows: firstly, this paper introduces the related knowledge of FMCW, including the advantages and disadvantages of FMCW radar and some applications of FMCW radar, as well as the working principle of FMCW radar. On this basis, MATLAB simulation is done, including continuous signal and four target echo. Aiming at the problem of emission leakage, this paper makes a deep analysis, including the channel of signal leakage, the principle of antenna reflection and the reflection power of antenna, and analyzes the influence of leakage noise on the performance of receiver. Secondly, the technical scheme of reflective power canceller (RPC), including analog cancellation scheme and digital cancellation scheme, is analyzed. On this basis, the advantages and disadvantages of the two schemes are analyzed. At the same time, the cancellation performance of the reflector is analyzed and studied, including the cancellation depth, wideband cancellation and cancellation performance evaluation. Finally, an improved scheme is proposed, which adopts adaptive cancellation structure and LMS algorithm. On this basis, the LMS algorithm is introduced, and the structure of the adaptive cancellation system is studied theoretically. The weighting coefficient, the output signal-to-interference ratio (the ratio of leakage signal to noise) and the signal-to-noise ratio (SNR) of the system are further analyzed. At the same time, the simulation of the system is carried out on MATLAB, including the system simulation of only leakage signal, the system simulation with noise, the system simulation with target, the system simulation with two leakage signals. System simulation of local oscillator signal with noise and system simulation with three target signals. In addition, the effect of step size on the system is studied and simulated.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN957.51

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