共查询到17条相似文献,搜索用时 640 毫秒
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简单介绍了PCI总线协议以及PCI接口原理。给出了一种利用单片机与复杂可编程逻辑器件CPLD(complex programmable logic device)控制PCI网卡,实现以太网通信的方案设计。重点说明了如何使用CPLD芯片设计单片机与PCI网卡之间的PCI接口。 相似文献
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BPM短波时码授时发播技术方案 总被引:1,自引:0,他引:1
为适应时频技术的迅速发展,进一步提高BPM短波授时发播系统的服务能力,扩展短波授时服务领域的用户面,在原有的BPM短波授时发播程序中增加短波时码信息是十分必要的.本文介绍了BPM时码授时发播的总体设计方案、BPM时码的格式以及解码流程等. 相似文献
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介绍BPM短波授时台新的载频产生器的设计与实现,该BPM载频产生器以原子频标的5MHz标频信号为参考,利用频率合成技术,产生出供发射机使用的2.5MHz、5MHz,10MHz、15MHz和20MHz五种高准确度的载频信号。这些信号既能单独输出,也可利用面板控制或遥控选择输出。为了保证系统的可靠性,采用了两冗余结构,并设置了必要的报警与指示。 相似文献
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根据伪码测距技术和卫星通讯的特点,针对我国已发射的或将要发射的以及我国目前租用的C波段和Ku波段卫星,设计了用高精密传输终端(或MITREX)进行伪码测距时卫星地面站的参数,并估算出了伪码测距精度。 相似文献
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基于CPLD的高精度可调脉冲信号发生器研制 总被引:1,自引:0,他引:1
为满足精密时间间隔测量设备的测试需要,研制了一种时间间隔可调的高精度脉冲信号发生器。利用计算机串口控制的方式,结合复杂可编程逻辑器件(CPLD)集成度高、可靠性好及工作速度快的优点,采用A1tera公司的设计软件QuartusII进行设计仿真及实现。仿真与实测实验表明,该脉冲信号发生器不仅可以产生单路可调脉冲信号,而且能产生多路可调脉冲信号,产生的单路秒脉冲信号的1s取样Allan方差为1.84×10^-11;产生的时间间隔为100ns的多路脉冲信号的1s取样Allan方差为2.36×10^-11,2路信号之间的时间间隔数据系列的峰一峰值为101ps,可以满足多通道时间间隔测量设备测试要求的稳定度与准确度。 相似文献
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M. Bocchi J. P. Chittenden A. Ciardi F. Suzuki-Vidal G. N. Hall P. de Grouchy S. V. Lebedev S. C. Bott 《Astrophysics and Space Science》2011,336(1):27-31
The aim of this work is to model the jets produced by conical wire arrays on the MAGPIE generator, and to design and test
new setups to strengthen the link between laboratory and astrophysical jets. We performed the modelling with direct three-dimensional
magneto-hydro-dynamic numerical simulations using the code GORGON. We applied our code to the typical MAGPIE setup and we
successfully reproduced the experiments. We found that a minimum resolution of ∼100 μm is required to retrieve the unstable
character of the jet. We investigated the effect of changing the number of wires and found that arrays with less wires produce
more unstable jets, and that this effect has magnetic origin. Finally, we studied the behaviour of the conical array together
with a conical shield on top of it to reduce the presence of unwanted low density plasma flows. The resulting jet is shorter
and less dense. 相似文献
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根据时统IRIG B(简称“B码”)的码形特点和编码原理 ,介绍利用计算机普通声卡接收标准化时统设备B码信号的硬件工作机理 ,着重阐述了软件解码的实现过程和为计算机提供标准时间的方法。 相似文献
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We present a hybrid technique of N -body simulation to deal with collisionless stellar systems having an inhomogeneous global structure. We combine a treecode and a self-consistent field code such that each of the codes models a different component of the system being investigated. The treecode is suited to treatment of dynamically cold or clumpy components, which may undergo significant evolution within a dynamically hot system. The hot system is appropriately evolved by the self-consistent field code. This combined code is particularly suited to a number of problems in galactic dynamics. Applications of the code to these problems are briefly discussed. 相似文献
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Kristian Finlator Feryal Özel Romeel Davé 《Monthly notices of the Royal Astronomical Society》2009,393(4):1090-1106
We introduce a new code for computing time-dependent continuum radiative transfer and non-equilibrium ionization states in static density fields with periodic boundaries. Our code solves the moments of the radiative transfer equation, closed by an Eddington tensor computed using a long characteristics (LC) method. We show that traditional short characteristics and the optically thin approximation are inappropriate for computing Eddington factors for the problem of cosmological re-ionization. We evolve the non-equilibrium ionization field via an efficient and accurate (errors <1 per cent) technique that switches between fully implicit or explicit finite differencing depending on whether the local time-scales are long or short compared to the time-step. We tailor our code for the problem of cosmological re-ionization. In tests, the code conserves photons, accurately treats cosmological effects and reproduces analytic Strömgren sphere solutions. Its chief weakness is that the computation time for the LC calculation scales relatively poorly compared to other techniques ( t LC ∝ N ∼1.5 cells ) ; however, we mitigate this by only recomputing the Eddington tensor when the radiation field changes substantially. Our technique makes almost no physical approximations, so it provides a way to benchmark faster but more approximate techniques. It can readily be extended to evolve multiple frequencies, though we do not do so here. Finally, we note that our method is generally applicable to any problem involving the transfer of continuum radiation through a periodic volume. 相似文献
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低频时码信号正交解调技术研究 总被引:2,自引:1,他引:1
采用正交叠加和正交采样技术,提出了更大程度上数字化的低频时码信号正交解调的设计方案。同时,分析了这种解调方法的虚假抑制和抗镜像干扰能力。分析表明所论述的解调技术易于实现数字化,且成本低廉,具有一定的实用价值。 相似文献