为了改善正交频分复用(orthogonal frequency division multiplexing,OFDM)在稀疏多径信道环境中的抗衰落能力,提出一种基于星座旋转调制OFDM系统的自适应交织方法。利用OFDM系统的多载波特点将旋转调制中的分量交织引入到子载波间交织...为了改善正交频分复用(orthogonal frequency division multiplexing,OFDM)在稀疏多径信道环境中的抗衰落能力,提出一种基于星座旋转调制OFDM系统的自适应交织方法。利用OFDM系统的多载波特点将旋转调制中的分量交织引入到子载波间交织,根据统计信道状态信息或实时信道状态信息,采用该文设计的交织器搜索准则来选取最佳分量交织图案,接收端将最佳的分量交织图案的索引反馈给发送端,实现了自适应交织。仿真结果表明该方法在稀疏多径衰落信道下有优异的抗衰落性能和较高的频谱利用率。展开更多
为提高复合线性调频(CLFM)信号的距离速度联合分辨力,提出了一种基于分数阶傅里叶变换的旋转线性调频(RLFM)信号,给出了设计方法,仿真得到了RLFM信号的模糊函数图、-3 d B模糊度图、距离模糊函数图及速度模糊函数图,最后将其与CLFM信号...为提高复合线性调频(CLFM)信号的距离速度联合分辨力,提出了一种基于分数阶傅里叶变换的旋转线性调频(RLFM)信号,给出了设计方法,仿真得到了RLFM信号的模糊函数图、-3 d B模糊度图、距离模糊函数图及速度模糊函数图,最后将其与CLFM信号进行了对比,结果显示,当旋转角度α满足1/2<cosα<5/6时,RLFM信号具有更好的速度分辨力和距离速度联合分辨力.展开更多
The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system（SINS） is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides ...The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system（SINS） is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides the enhanced property of SINS when using the same-leveled inertial measurement units. Then, the rotating struc- ture modification is derived and augmented to resolve the un-modulated error-accumulated problem. As the insuf- ficient machine processing, the horizontal and the vertical errors on the machine surface are inevitable, and the in- volved coordinates are difficult to get the exact coincident. So, two major kinds of coordinate situation are stud- ied. The equivalent error models on gyro and acceleration outputs are built for each situation, and the impact is analyzed for compensation. The part of attitude and position error models caused by the built angle-rate error is established to calculate the un-eoincident impact. Considering these conditions of different gyro accuracy and mo- tion states simultaneously, numerical simulations are implemented. Results indicate that the SINS modulation ac- curacy is seriously affected by the combined factors on gyro accuracy and motion conditions.展开更多
文摘为了改善正交频分复用(orthogonal frequency division multiplexing,OFDM)在稀疏多径信道环境中的抗衰落能力,提出一种基于星座旋转调制OFDM系统的自适应交织方法。利用OFDM系统的多载波特点将旋转调制中的分量交织引入到子载波间交织,根据统计信道状态信息或实时信道状态信息,采用该文设计的交织器搜索准则来选取最佳分量交织图案,接收端将最佳的分量交织图案的索引反馈给发送端,实现了自适应交织。仿真结果表明该方法在稀疏多径衰落信道下有优异的抗衰落性能和较高的频谱利用率。
文摘为提高复合线性调频(CLFM)信号的距离速度联合分辨力,提出了一种基于分数阶傅里叶变换的旋转线性调频(RLFM)信号,给出了设计方法,仿真得到了RLFM信号的模糊函数图、-3 d B模糊度图、距离模糊函数图及速度模糊函数图,最后将其与CLFM信号进行了对比,结果显示,当旋转角度α满足1/2<cosα<5/6时,RLFM信号具有更好的速度分辨力和距离速度联合分辨力.
基金Supported by the National Natural Science Foundation of China(60702003)the Aviation Science Foundation(20080852011)+1 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China(20070287045)the NUAA Research Fundation(NS2010066)~~
文摘The un-coincide coordinate error in the single-axis rotating fiber optic strap-down inertial navigation system（SINS） is analyzed. Firstly, a rotating modulation technology is presented for SINS. The method provides the enhanced property of SINS when using the same-leveled inertial measurement units. Then, the rotating struc- ture modification is derived and augmented to resolve the un-modulated error-accumulated problem. As the insuf- ficient machine processing, the horizontal and the vertical errors on the machine surface are inevitable, and the in- volved coordinates are difficult to get the exact coincident. So, two major kinds of coordinate situation are stud- ied. The equivalent error models on gyro and acceleration outputs are built for each situation, and the impact is analyzed for compensation. The part of attitude and position error models caused by the built angle-rate error is established to calculate the un-eoincident impact. Considering these conditions of different gyro accuracy and mo- tion states simultaneously, numerical simulations are implemented. Results indicate that the SINS modulation ac- curacy is seriously affected by the combined factors on gyro accuracy and motion conditions.
