In the high speed target environment,there exists serious Doppler effect in the low pulse repetition frequency（LPRF） modulated frequency stepped frequency（MFSF） radar signal.The velocity range of the target is lar...In the high speed target environment,there exists serious Doppler effect in the low pulse repetition frequency（LPRF） modulated frequency stepped frequency（MFSF） radar signal.The velocity range of the target is large and the velocity is high ambiguous,so the single method is difficult to satisfy the velocity measurement requirement.For this problem,a novel method is presented,it is a combination of cross-correlation inner frame velocity measurement and range-Doppler coupling velocity measurement.The cross-correlation inner frame method,overcoming the low Doppler tolerance of the cross-correlation between frames,can obtain the coarse velocity of the high speed target,and then the precision velocity can be obtained with the range-Doppler coupling method.The simulation results confirm the method is effective,and also it is well real-time and easy to the project application.展开更多
The behavior of a RF-excited waveguide CO2 laser in the pulse regime is studied theoretically. The output pulse evolution is studied by applying three types of pulses namely the square, sine and the triangular ones as...The behavior of a RF-excited waveguide CO2 laser in the pulse regime is studied theoretically. The output pulse evolution is studied by applying three types of pulses namely the square, sine and the triangular ones as the excitation pulses. The frequency dependence behavior of the output pulse is also presented.展开更多
针对原边反馈反激变换器具有辅助绕组而成本偏高的问题,基于原边反馈与峰值电流控制方案,提出了一种基于开关管漏极反馈的反激变换器模型。与原边反馈反激变换器相比,漏极反馈反激变换器能够减少变压器辅助绕组,降低了成本,且具有较高...针对原边反馈反激变换器具有辅助绕组而成本偏高的问题,基于原边反馈与峰值电流控制方案,提出了一种基于开关管漏极反馈的反激变换器模型。与原边反馈反激变换器相比,漏极反馈反激变换器能够减少变压器辅助绕组,降低了成本,且具有较高的稳定性。首先,对此漏极反馈反激变换器模型进行了理论分析,并提出了一种高精度漏极采样方法。其次,基于开关网络模型法对工作在断续导通模式(Discontinuous conduction mode,DCM)下脉冲频率调制(Pulse frequency modulation,PFM)的漏极反馈反激变换器进行了小信号建模并进行补偿设计。通过Matlab/Simulink搭建模型验证其正确性;最后搭建试验平台来进行验证。结果表明,所提出的漏极反馈反激变换器模型是可行的。展开更多
提出一种可根据负载变化在脉冲宽度调制(pulse width modulation,PWM)和脉冲频率调制(pulse frequency modulation,PFM)两种工作模式间自动切换的降压DC-DC芯片的设计法,推导出临界切换状态下的负载电流值表达式,在此基础上设计了一种PW...提出一种可根据负载变化在脉冲宽度调制(pulse width modulation,PWM)和脉冲频率调制(pulse frequency modulation,PFM)两种工作模式间自动切换的降压DC-DC芯片的设计法,推导出临界切换状态下的负载电流值表达式,在此基础上设计了一种PWM/PFM自动切换的DC-DC芯片.该系统在较大的负载变化范围内均具有较高效率.展开更多
针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长...针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长短时记忆网络挖掘原始脉冲流中LFM信号与非LFM信号的调制模式差异并进行分类;其次通过序列调频斜率直方图寻找LFM信号分裂脉冲序列间隐含的原始信号调频斜率信息,提取不同调频斜率的LFM信号脉冲子序列;最后在每个子序列中分别估计原始信号的参数。仿真实验结果表明,相较于传统的序列差值直方图算法和循环神经网络分选方法,本文所提方法能够更准确地提取出LFM脉冲信号,并得到较为精确的参数估计结果。展开更多
针对红外光通信存在的调制解调复杂、传输距离短等问题,提于一种新颖的脉冲频率（pulse frequency modulation,PFM）调制方式,并设计了4阶带通滤波器滤除带通噪声,构建接收转发电路延长了传输距离。研制了一套宽角度的红外光音频传输系...针对红外光通信存在的调制解调复杂、传输距离短等问题,提于一种新颖的脉冲频率（pulse frequency modulation,PFM）调制方式,并设计了4阶带通滤波器滤除带通噪声,构建接收转发电路延长了传输距离。研制了一套宽角度的红外光音频传输系统。音频传输实验结果表明：该系统实现了较好的音频传输效果,降低了红外光通信系统在传输过程中的功率损耗,延长了传输距离,同时实现了0°~360°传输方向的自主调节,表明本系统具有良好的工程应用价值。展开更多
为实现一种结构简单,高效、高频、低电压应力,控制简单的软开关升压变换器,提出一种零电流软开关脉冲频率调制(pulse frequency modulation,PFM)变换器,并以其在boost变换器的应用为例分析了其工作原理、软开关实现条件以及该电路的设...为实现一种结构简单,高效、高频、低电压应力,控制简单的软开关升压变换器,提出一种零电流软开关脉冲频率调制(pulse frequency modulation,PFM)变换器,并以其在boost变换器的应用为例分析了其工作原理、软开关实现条件以及该电路的设计方法.仿真和实验结果表明:该变换器在较宽的输出电压、输入电压、负载及控制频率变化范围内,能够实现稳定的零电流开关.该软开关设计思想可以推广到其他基本DC-DC变换器中.展开更多
文摘In the high speed target environment,there exists serious Doppler effect in the low pulse repetition frequency（LPRF） modulated frequency stepped frequency（MFSF） radar signal.The velocity range of the target is large and the velocity is high ambiguous,so the single method is difficult to satisfy the velocity measurement requirement.For this problem,a novel method is presented,it is a combination of cross-correlation inner frame velocity measurement and range-Doppler coupling velocity measurement.The cross-correlation inner frame method,overcoming the low Doppler tolerance of the cross-correlation between frames,can obtain the coarse velocity of the high speed target,and then the precision velocity can be obtained with the range-Doppler coupling method.The simulation results confirm the method is effective,and also it is well real-time and easy to the project application.
文摘The behavior of a RF-excited waveguide CO2 laser in the pulse regime is studied theoretically. The output pulse evolution is studied by applying three types of pulses namely the square, sine and the triangular ones as the excitation pulses. The frequency dependence behavior of the output pulse is also presented.
文摘针对原边反馈反激变换器具有辅助绕组而成本偏高的问题,基于原边反馈与峰值电流控制方案,提出了一种基于开关管漏极反馈的反激变换器模型。与原边反馈反激变换器相比,漏极反馈反激变换器能够减少变压器辅助绕组,降低了成本,且具有较高的稳定性。首先,对此漏极反馈反激变换器模型进行了理论分析,并提出了一种高精度漏极采样方法。其次,基于开关网络模型法对工作在断续导通模式(Discontinuous conduction mode,DCM)下脉冲频率调制(Pulse frequency modulation,PFM)的漏极反馈反激变换器进行了小信号建模并进行补偿设计。通过Matlab/Simulink搭建模型验证其正确性;最后搭建试验平台来进行验证。结果表明,所提出的漏极反馈反激变换器模型是可行的。
文摘提出一种可根据负载变化在脉冲宽度调制(pulse width modulation,PWM)和脉冲频率调制(pulse frequency modulation,PFM)两种工作模式间自动切换的降压DC-DC芯片的设计法,推导出临界切换状态下的负载电流值表达式,在此基础上设计了一种PWM/PFM自动切换的DC-DC芯片.该系统在较大的负载变化范围内均具有较高效率.
文摘针对多雷达辐射源脉冲交错背景下,线性调频(Linear Frequency Modulation,LFM)信号低信噪比导致的脉冲分裂带来原始信号参数难以估计的问题,本文提出了基于深度神经网络和直方图统计的LFM信号两阶段提取与参数估计方法。首先利用双向长短时记忆网络挖掘原始脉冲流中LFM信号与非LFM信号的调制模式差异并进行分类;其次通过序列调频斜率直方图寻找LFM信号分裂脉冲序列间隐含的原始信号调频斜率信息,提取不同调频斜率的LFM信号脉冲子序列;最后在每个子序列中分别估计原始信号的参数。仿真实验结果表明,相较于传统的序列差值直方图算法和循环神经网络分选方法,本文所提方法能够更准确地提取出LFM脉冲信号,并得到较为精确的参数估计结果。
文摘针对红外光通信存在的调制解调复杂、传输距离短等问题,提于一种新颖的脉冲频率（pulse frequency modulation,PFM）调制方式,并设计了4阶带通滤波器滤除带通噪声,构建接收转发电路延长了传输距离。研制了一套宽角度的红外光音频传输系统。音频传输实验结果表明：该系统实现了较好的音频传输效果,降低了红外光通信系统在传输过程中的功率损耗,延长了传输距离,同时实现了0°~360°传输方向的自主调节,表明本系统具有良好的工程应用价值。
文摘为实现一种结构简单,高效、高频、低电压应力,控制简单的软开关升压变换器,提出一种零电流软开关脉冲频率调制(pulse frequency modulation,PFM)变换器,并以其在boost变换器的应用为例分析了其工作原理、软开关实现条件以及该电路的设计方法.仿真和实验结果表明:该变换器在较宽的输出电压、输入电压、负载及控制频率变化范围内,能够实现稳定的零电流开关.该软开关设计思想可以推广到其他基本DC-DC变换器中.
