基于仿真的雷达系统非线性分析

发布时间：2018-11-10 19:03

【摘要】：现代雷达在军事设备,民事领域以及科研项目中应用越来越广泛,因而受到世界各国的重视。信号是雷达系统的中心,由于实现的灵活性,输出频率的准确度高等优,直接数字波形合成技术目前已经被广泛应用于实际雷达工程中。随着数字技术的发展,数字中频技术也被引入雷达发射和接收系统中,进一步提高了雷达系统的性能。为了提高雷达的检测能力,信号处理一般先采取匹配接收,使得输出信噪比达到最大。同时,信号产生方式的固有局限性以及发射接收(T/R)的模拟器件限制等非线性因素,会给雷达接收信号引入复杂的杂散以及干扰,对雷达性能产生影响。本文主要对雷达系统的信号源以及发射接收通道中可能出现的非线性进行详细的分析。首先介绍直接数字波形合成技术的基本原理,对DDS非线性导致的输出信号中不同杂散成分进行详细分析,包括相位截断,幅度量化,DAC非线性。之后分析雷达发射接收链路中由模拟器件非线性导致的交调特性,并推导了系统各非线性指标间定量关系。仿真主要基于systemvue对雷达系统进行建模实现。本文重点仿真DDS及发射接收系统的非线性对于雷达探测性能的影响。通过DDS生成线性调频信号(LFM),根据数字处理非线性导致的单频信号杂散对LFM信号的杂散进行定性的分析,仿真分析其对雷达探测的影响;得出由DDS非线性产生的线性调频信号中杂散噪声对于匹配接收的影响主要是降低输出信噪比,影响雷达探测目标的灵敏度。对于系统非线性主要分析不同目标环境下,由非线性引起的交调干扰对雷达探测的影响。仿真表明,无论单目标还是多目标环境,发射机非线性对雷达探测都不会产生影响;而接收机的非线性在多目标环境下产生的交调干扰会产生假目标,对雷达探测产生干扰。
[Abstract]:Modern radar is more and more widely used in military equipment, civil affairs and scientific research projects. Signal is the center of radar system. Because of the flexibility of realization and the high accuracy of output frequency, direct digital waveform synthesis technology has been widely used in practical radar engineering. With the development of digital technology, digital intermediate frequency technology is introduced into radar transmitting and receiving system, which improves the performance of radar system. In order to improve the detection ability of radar, the signal processing usually adopts matching reception, which makes the output signal-to-noise ratio maximum. At the same time, the inherent limitation of signal generation and the limitation of analog devices such as transmitting and receiving (T / R) will introduce complex spurious and interference to radar reception signal, which will have an impact on radar performance. In this paper, the signal source of radar system and the possible nonlinearity in transmitting and receiving channel are analyzed in detail. Firstly, the principle of direct digital waveform synthesis is introduced, and the different spurious components in the output signal caused by DDS nonlinearity are analyzed in detail, including phase truncation, amplitude quantization and DAC nonlinearity. After that, the intermodulation characteristics caused by the nonlinearity of analog devices in the radar transmit and receive link are analyzed, and the quantitative relationship among the nonlinear indexes of the system is deduced. The simulation is mainly based on systemvue to model the radar system. In this paper, the influence of DDS and the nonlinearity of transmitting and receiving system on radar detection performance is simulated. The linear frequency modulation signal (LFM),) is generated by DDS. According to the single frequency signal spurious caused by digital processing, the spurious signal of LFM signal is analyzed qualitatively, and the influence on radar detection is analyzed by simulation. It is concluded that the influence of spurious noise on matching reception in linear frequency modulated signals generated by DDS is mainly to reduce the output signal-to-noise ratio (SNR) and affect the sensitivity of radar target detection. For the system nonlinearity, the influence of nonlinear intermodulation jamming on radar detection is mainly analyzed in different target environments. Simulation results show that the transmitter nonlinearity has no effect on radar detection whether in single target environment or multi-target environment, while the cross-modulation jamming generated by receiver nonlinearity in multi-target environment will cause false target and jamming radar detection.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN95

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