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
Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy ...Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy sub-nanosecond Q-switched lasers is proposed and verified in experiment.When a Nd:YVO4 crystal with a doping concentration of 0.7 at.%is used as a gain medium and a driving signal with the optimal high-level voltage is applied to the Pockels cell,a stable single-transverse-mode electro-optical Q-switched laser with a pulse width of 0.77 ns and a pulse energy of 1.04 mJ operating at the pulse repetition frequency of 1 kHz is achieved.The precise tuning of the pulse width is also demonstrated.展开更多
在医科达直线加速器运行过程中,程控脉冲信号发生器(Programmable Pulse Generator,PPG)PCB会发出脉冲重复频率(Pulse Repetition Frequency,PRF)ENABLE信号,依次经过3个控制区和多叶准直器以及直线加速器控制系统(Linac Control System...在医科达直线加速器运行过程中,程控脉冲信号发生器(Programmable Pulse Generator,PPG)PCB会发出脉冲重复频率(Pulse Repetition Frequency,PRF)ENABLE信号,依次经过3个控制区和多叶准直器以及直线加速器控制系统(Linac Control System,LCS)回到PPG PCB,如果各区域工作正常,则PPG PCB会向高压部分提供闸流管脉冲触发,脉冲成形网络会正常充放电,磁控管产生微波到加速管加速电子,加速器工作正常。如果PRF ENABLE信号经过的区域有工作异常的情况,则加速器不能正常出束。我院医科达直线加速器的临床使用过程中,多次出现PRF EN CHK连锁。本文总结我院医科达Synergy直线加速器运行过程中出现的PRF EN CHK连锁,详细分析了已出现故障或者可能发生的故障,重点介绍了排除故障的过程,供相关人员参考。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.
基金the National Key Research and Development Program of China(Grant No.2017YFB0405203)the Shanxi“1331 Project”Key Subjects Construction,China(Grant No.1331KSC).
文摘Based on a theoretical model of Q-switched laser with the influences of the driving signal sent to the Pockels cell and the doping concentration of the gain medium taken into account,a method of achieving high energy sub-nanosecond Q-switched lasers is proposed and verified in experiment.When a Nd:YVO4 crystal with a doping concentration of 0.7 at.%is used as a gain medium and a driving signal with the optimal high-level voltage is applied to the Pockels cell,a stable single-transverse-mode electro-optical Q-switched laser with a pulse width of 0.77 ns and a pulse energy of 1.04 mJ operating at the pulse repetition frequency of 1 kHz is achieved.The precise tuning of the pulse width is also demonstrated.
基金National Nature Science Foundation of China(Grant No.60972159,61032001)Aviation Science Foundation(Grant No.20085184003)Special Foundation Program for Mountain Tai Scholars of China
文摘在医科达直线加速器运行过程中,程控脉冲信号发生器(Programmable Pulse Generator,PPG)PCB会发出脉冲重复频率(Pulse Repetition Frequency,PRF)ENABLE信号,依次经过3个控制区和多叶准直器以及直线加速器控制系统(Linac Control System,LCS)回到PPG PCB,如果各区域工作正常,则PPG PCB会向高压部分提供闸流管脉冲触发,脉冲成形网络会正常充放电,磁控管产生微波到加速管加速电子,加速器工作正常。如果PRF ENABLE信号经过的区域有工作异常的情况,则加速器不能正常出束。我院医科达直线加速器的临床使用过程中,多次出现PRF EN CHK连锁。本文总结我院医科达Synergy直线加速器运行过程中出现的PRF EN CHK连锁,详细分析了已出现故障或者可能发生的故障,重点介绍了排除故障的过程,供相关人员参考。
