【作者】 顾村锋；

【导师】 吴文； Law Choi Look；

【作者基本信息】 南京理工大学 ， 通信与信息系统， 2010， 博士

【摘要】 基于OFDM技术的多载波补码相位编码(MCPC)高分辨雷达具有图钉型模糊函数、控制简单、生成便利和易与现代通信系统兼容等优点,已成为高分辨力雷达技术和雷达通信双功能电子系统的重要发展方向和研究热点。本文将MCPC技术和宽带极化雷达技术相结合,设计了同时极化频率捷变MCPC雷达系统,着重对MCPC雷达的波形设计、功率放大器非线性效应补偿、宽带频率调制IQ不平衡补偿几项关键技术进行了深入系统的研究,具体研究内容和主要成果包括：1.结合过采样技术,通过改变调制序列来动态调整载波间隔的方式,设计了改进型MCPC雷达信号产生方案和具有多普勒免疫的信号检测方法。理论分析和仿真结果表明：与传统的MCPC雷达相比,本文所设计的MCPC雷达具有更高的距离分辨力、多普勒容忍度和载波间相位噪声互干扰免疫能力,并消除了DC offset对探测性能的影响。2.利用MCPC雷达信号具有可以实现目标散射矩阵同时测量的特点,结合频率捷变技术设计了同时极化频率捷变MCPC雷达系统,大大提高了系统抗有源干扰的能力。研制了频率捷变频率合成器,为同时极化频率捷变MCPC雷达系统研制奠定了技术基础。3.通过优化MCPC雷达信号各载波权重因子来实现信号低峰均比(PMEPR)和低自相关函数旁瓣。优化结果表明：通过加权优化的MCPC脉冲串,PMEPR可降低至66.9%,主旁瓣比提高5dB。提出利用单个MCPC雷达信号脉冲连续发射两次的信号结构和回波信号自相关信息来提取参数,实现对功率放大器的非线性效应的实时补偿。该补偿方法不仅使非线性补偿过程免受多普勒和噪声影响,且保留了信号中的多普勒信息。4.通过将MCPC雷达信号频带细分,并利用雷达回波信号与原发射信号的互相关函数来提取IQ不平衡参数实现对宽带频率调制IQ不平衡时域补偿。补偿过程中,利用MCPC信号间的相关特性去除噪声影响,并采用MCPC信号间的非相关性简化由频带细分增加的计算量。分析和仿真结果表明所提出的补偿方法在宽带和低信噪比的情况下,能有效地实现IQ不平衡度补偿。更多还原

【Abstract】 Multi-carrier Complementary Phase-coded (MCPC) radar signal which is based on Or-thogonal Frequency Division Multiplexing (OFDM) technique exhibits thumbtack ambigu-ity function. It is easy to be controlled, generated and compatible with modern communica-tion systems. By combining MCPC technique and wideband polarization radar technique, a simultaneous polarization frequency agility MCPC radar system is designed, and of which key techniques are intensive researched including MCPC radar signal waveform design, power amplifier nonlinear effects compensation and wideband frequency-dependent IQ im-balance compensation. The main work and contributions of this dissertation are listed as follows.1. An improved way to generate MCPC radar signal and a Doppler resisted signal de-tection method are proposed by combining oversampling technique. The proposed approach improved MCPC radar performance by modifying modulation sequences to adjust subcarrier spacing dynamically. Theory analysis and simulation results show that the proposed MCPC radar system has higher delay resolution, Doppler tolarence and immune to Foreign Contri-bution (FC) of phase noise between carriers, and the influences of DC offset are eliminated.2. By combining frequency agility technique and MCPC radar technique which is very suitable for simultaneous scattering matrix measurement technique implementation, a si-multaneous polarization frequency agility MCPC radar system is designed. Both these tech-niques improve system immunity to active jamming greatly. A frequency aigilty frequency synthesizer is designed and manufactured, which provides technique foundation for simul-taneous polarization frequency agility MCPC radar system implementation.3. By optimizing MCPC radar signal frequency weights, low signal Peak-to-Mean En-velope Power Ratio (PMEPR) and low auto-correlation sidelobe are realized. The optimiza-tion result shows that PMEPR of MCPC radar signal pulse train can be reduced to 66.7%, while mainlobe to sidelobe ratio can increase by 5dB. The signal structure of double trans-mitting single MCPC pulse and radar echoes self-correlation method are used for power amplifier nonlinear parameters extraction and compensation. The proposed approach can separate nonlinear effects and Doppler influence. The compensation procedures are immune to Doppler and noise. And the Doppler information can be reserved.4. By subdividing frequency spectrum and extracting IQ imbalance parameters from the cross-correlaiton function of radar echoes and original transmitted signal, a time domain IQ compensation approach is proposed for frequency-dependent IQ imbalance in wideband scenarios. In the compensation procedures, MCPC signal correlation properties are used for noise elimination and uncorrelated properties between MCPC signals are used to simplify calculation which increases with frequcny spectrum subdivision. Analysis and simulation results show that the proposed approach can compensate IQ imbalance effectively in wide-band and low Signal-to-Noise Ratio (SNR) scenarios.更多还原