该文针对单相并网系统提出了一种基于微分环节的锁相环方法。将微分环节与二阶滤波环节相结合所构造出的正交信号发生器,能有效地抑制谐波,且不依赖于频率反馈。通过采用两个微分环节能够实现精确的鉴相,进而通过合理设计参数可以实现...该文针对单相并网系统提出了一种基于微分环节的锁相环方法。将微分环节与二阶滤波环节相结合所构造出的正交信号发生器,能有效地抑制谐波,且不依赖于频率反馈。通过采用两个微分环节能够实现精确的鉴相,进而通过合理设计参数可以实现性能优良的锁相环。该文首先建立了锁相环的数学模型,接着对其性能进行了详细论证。最后,研究了数字算法的实现,并针对离散化过程所带来的误差进行了补偿。该文基于Matlab/Simulink完成了锁相环的仿真,并通过数字信号处理(digital signal processor,DSP)完成了相关实验。仿真与实验结果表明,该文提出的锁相环具有很好的谐波滤除能力及动态性能。该锁相环方法适用于各种单相并网系统。展开更多
We demonstrate a scheme to use a Littman configuration external cavity diode laser （ECDL） as a stablefrequency light source to stabilize two cw single-mode Ti：sapphire lasers for laser cooling of magnesium fluoride...We demonstrate a scheme to use a Littman configuration external cavity diode laser （ECDL） as a stablefrequency light source to stabilize two cw single-mode Ti：sapphire lasers for laser cooling of magnesium fluoride molecules. An ECDL based on the Littman configuration is constructed and stabilized by a digital signal processor system. We stabilize the frequency of our ECDL to 4-0.77 MHz precision over 10 h and the Allan standard deviation reaches 2.6 × 10-11 at an integration time of 10 s. We lock two Ti：sapphire lasers through a transfer cavity, and either laser has a long-term frequency stability of 4-2.5 MHz.展开更多
A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-c...A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.展开更多
文摘该文针对单相并网系统提出了一种基于微分环节的锁相环方法。将微分环节与二阶滤波环节相结合所构造出的正交信号发生器,能有效地抑制谐波,且不依赖于频率反馈。通过采用两个微分环节能够实现精确的鉴相,进而通过合理设计参数可以实现性能优良的锁相环。该文首先建立了锁相环的数学模型,接着对其性能进行了详细论证。最后,研究了数字算法的实现,并针对离散化过程所带来的误差进行了补偿。该文基于Matlab/Simulink完成了锁相环的仿真,并通过数字信号处理(digital signal processor,DSP)完成了相关实验。仿真与实验结果表明,该文提出的锁相环具有很好的谐波滤除能力及动态性能。该锁相环方法适用于各种单相并网系统。
基金supported by the National Natural Science Foundation of China(Nos.11374100,91536218,and 11274114)the Natural Science Foundation of Shanghai Municipality(No.13ZR1412800)
文摘We demonstrate a scheme to use a Littman configuration external cavity diode laser （ECDL） as a stablefrequency light source to stabilize two cw single-mode Ti：sapphire lasers for laser cooling of magnesium fluoride molecules. An ECDL based on the Littman configuration is constructed and stabilized by a digital signal processor system. We stabilize the frequency of our ECDL to 4-0.77 MHz precision over 10 h and the Allan standard deviation reaches 2.6 × 10-11 at an integration time of 10 s. We lock two Ti：sapphire lasers through a transfer cavity, and either laser has a long-term frequency stability of 4-2.5 MHz.
文摘A new method is proposed for the object surveillance system based on the enhanced fish-eye lens and the high speed digital signal processor （DSP）. The improved fish-eye lens images an ellipse picture on the charge-coupled device （CCD） surface, which increases both the utilization rate of the 4：3 rectangular CCD and the imaging resolution, and remains the view angle of 183° The algorithm of auto-adapted renewal background subtraction （ARBS） is also explored to extract the object from the monitoring image. The experimental result shows that the ARBS algorithm has high anti-jamming ability and high resolution, leading to excellent object detecting ability from the enhanced elliptical fish-eye image under varies environments. This system has potential applications in different security monitoring fields due to its wide monitoring space, simple structure, working stability, and reliability.
