共查询到20条相似文献,搜索用时 11 毫秒
1.
基于DPIM调制的MIMO空间光通信系统 总被引:1,自引:0,他引:1
为了抑制空间光通信中大气湍流效应和降低误包率,提出了一种引入分布式多出多入技术,基于数字脉冲间隔调制的多出多入空间光通信系统.在弱湍流信道模型和APD探测器下建立了多出多入系统链路模型,推导了最大似然检测下的最佳阈值和误包率.计算结果表明:发射分集通过多路径传输平滑接收信号光强起伏;接收分集增加孔径平滑效应,减弱接收光强起伏;在发射平均功率、接收孔径总面积和背景噪音相同的条件下,数字脉冲间隔调制的不同多出多入系统存在几乎相同的最佳雪崩光电二极管增益;比较多出多入通信系统下三种调制方式,数字脉冲间隔调制的误包率较少劣于PPM调制而大大优于OOK调制. 相似文献
2.
3.
Robertson Scott 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1978,6(3):266-269
Simple analog data processing circuits are described which transmit serially over a single transmission line the integrated outputs of a multichannel Thomson scattering diagnostic system. The small, battery powered circuits may be mounted in the photomultiplier tube housing for maximum noise rejection. 相似文献
4.
Within the Feynman–Kac path integral representation, the equilibrium quantities of a quantum plasma can be represented by Mayer graphs. The well known Coulomb divergencies that appear in these series are eliminated by partial resummations. In this paper, we propose a resummation scheme based on the introduction of a single effective potential that is the quantum analog of the Debye potential. A low density analysis of shows that it reduces, at short distances, to the bare Coulomb interaction between the charges (which is able to lead to bound states). At scale of the order of the Debye screening length
–1
D, approaches the classical Debye potential and, at large distances, it decays as a dipolar potential (this large distance behaviour is due to the quantum nature of the particles). The prototype graphs that result from the resummation obey the same diagrammatical rules as the classical graphs of the Abe–Meeron series. We give several applications that show the usefulness of to account for Coulombic effects at all distances in a coherent way. 相似文献
5.
The problems of using functional electronics in radio communication and radio-signal processing systems are considered. Different methods of radio access are compared from the viewpoint of throughput and efficiency of frequency resource usage. The prospects for applying systems with code division of channels using matched filters on surface acoustic waves are shown. The results of research and development of various acousto-optical devices, including radio-signal spectrum analyzers, direction finders – frequency meters, and demodulators of phase-shift keyed signals are presented. 相似文献
6.
A brief history of attempts to use solitons for optical fiber communications and of the technical developments toward making soliton transmission practical is reviewed. The main problems affecting long-distance soliton transmission, as well as techniques to solve them, are described. Recent developments concerning the use of dispersion management and some of the remarkable properties of dispersion managed solitons are also discussed. 相似文献
7.
M. F. FERREIRA M. V. FACÃO S. V. LATAS M. H. SOUSA 《Fiber and Integrated Optics》2013,32(3-4):287-313
Abstract A brief history of attempts to use solitons for optical fiber communications and of the technical developments toward making soliton transmission practical is reviewed. The main problems affecting long-distance soliton transmission, as well as techniques to solve them, are described. Recent developments concerning the use of dispersion management and some of the remarkable properties of dispersion managed solitons are also discussed. 相似文献
8.
Nonlocality Distillation and Trivial Communication Complexity for High-Dimensional Systems
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
《中国物理快报》2016,(8)
A nonlocality distillation protocol for arbitrary high-dimensional systems is proposed.We study the nonlocality distillation in the 2-input d-output bi-partite case.Firstly,we give the one-parameter nonlocal boxes and their correlated distilling protocol.Then,we generalize the one-parameter nonlocality distillation protocol to the twoparameter case.Furthermore,we introduce a contracting protocol testifying that the 2-input d-output nonlocal boxes make communication complexity trivial. 相似文献
9.
10.
R. Pugliesi Fábio Pugliesi M. A. Stanojev Pereira 《Brazilian Journal of Physics》2011,41(2-3):123-128
The characteristics of three digital imaging systems for neutron radiography purposes have been compared. Two of them make use of films, CR-39 and Kodak AA, and the third makes use of a LiF scintillator, for image registration. The irradiations were performed in the neutron radiography facility installed at the IEA-R1 nuclear research reactor of IPEN-CNEN/SP. According to the obtained results, the system based on CR-39 is the slowest to obtain an image, and the best in terms of resolution but the worse in terms of contrast. The system based on Kodak AA is faster than the prior, exhibits good resolution and contrast. The system based on the scintillator is the fastest to obtain an image, and best in terms of contrast but the worse in terms of resolution. 相似文献
11.
Bernd Müller 《Communications in Mathematical Physics》1998,191(1):1-13
We consider Quantum Communication Systems (QCS's), introduced by Davies [10] on trace class operators, on general state spaces.
These are different from the usual quantum information theory as they deal with input and output being continuous in time.
We introduce the concept of a refinement of a QCS, offering the possibility of distinguishing particles, for instance according
to their phase or location, and classify refinements of general QCS. We then introduce the notions of a bounded interaction
rate and a bounded modulation and give, in special cases, a classification of QCS's satisfying both conditions. As this classification
shows the existence of a class of QCS's being completely different from the examples studied by Davies, we are able to discuss
the cases of an independent detector and a linear modulation.
Received: 5 September 1995 / Accepted: 5 November 1996 相似文献
12.
13.
当前数字化闭环控制航天伺服系统测试时采用一种基于1553B总线控制和A/D模拟采集的测控系统设备,当进行动态特性测试时,1553B与A/D间的启动延迟导致测试结果的精度不准确。为了消除数模混合控制系统下启动零点误差对伺服系统动态特性的影响,对启动零点误差来源进行了分析,在伺服系统1553B总线架构数字化闭环控制的基础上,采用基于PXI硬件平台的数字与模拟采集启动零点同步技术,解决了由于启动同步时间差导致伺服系统动态特性数据处理结果跳变的问题,大大提高了伺服测控系统的测试精度。 相似文献
14.
宋光乐 《光谱学与光谱分析》2003,23(4):820-822
从Fourier级数出发 ,到任意闭区间上可积函数的Fourier分析 ,给出了数字信号Fourier分析的理论基础。以字符“b”为例 ,建立了严格的数学模型 ,严密推导了Fourier系数表达式。阐明了Fourier级数的“项”和“n阶Fourier级数”(前n项和 )的概念。详尽地分析了信道通频带B与Fourier阶数n(展开式“保留”项 )的关系。借助计算机计算了n≤ 10 0时各Fourier级数项和前n项和 ,并用Plot将计算结果绘成曲线 ,获得n≤10 0时各级Fourier展开曲线。与数字信号对照 ,Fourier级数的取项与波形的关系显而易见 ,特别是n取值较小时 ,Fourier级数取项少 ,波形失真严重 ;所以在B一定时传输速率不能过高 ,否则 ,由于波形失真而导致信号出错。 相似文献
15.
光通信数字接收中位同步信号的智能提取 总被引:1,自引:0,他引:1
在光通信数字接收机中,为了达到系统的位同步,结合数字锁相环的基本原理,采用现场可编程技术,设计了位同步信号的时序逻辑电路,并用FPGA芯片实现了整个位同步电路.通过单片机实时控制FPGA,进行频带宽度和中心频率的实时调节,实现了位同步信号的智能提取.仿真分析和实际测试表明,该系统具有实时跟踪,提取快速且稳定,抗干扰能力强,升级方便等特点. 相似文献
17.
V. Bardinal T. Camps E. Daran C. Amat G. Almuneau C. Bringer M. Suleiman C. Fontaine 《Optical and Quantum Electronics》2006,38(4-6):523-534
We have investigated experimentally the optical behaviour of a Vertical-Cavity Surface-Emitting Lasers (VCSEL) when it is
used as a lateral waveguide. This provides a better understanding of the mechanisms involved in VCSEL optical power monitoring
by integrated lateral detection. The lateral optical spectra as well as the waveguide transmission spectrum have been measured.
Their analysis and comparison demonstrate that the lateral signal is mostly coming from the spontaneous emission escaping
laterally from the VCSEL and that light is filtered during the propagation and detection processes. This allows us to explain
previous results obtained in two different configurations of lateral detection. These results are useful to optimize the lateral
detection performances for concrete applications in monitoring or telemetry systems. 相似文献
18.
传统的航天器地面综测系统软件间通信协议一般是根据不同航天器的测试任务和测试特点而制定的,没有形成统一规范,各航天器综测系统软件协议和接口的差别甚大,导致综测系统软件可移植性差;针对现有航天器地面综测系统软件间通信协议可扩展性能差的现状,以新型小卫星地面综测系统的设计研发为依托,探索并设计了一套基于XML描述与传输的通信协议,开发了地面综测系统软件,并对该通信协议进行了实现和试验;经试验证明,利用XML描述与传输的综测系统软件协议和XML串行化反串行化技术,该通信协议具备良好的操作性和可扩展性,较大的简化了航天器地面综测系统软件间的接口设计,增强了综测系统软件的可移植性。 相似文献
19.
针对APU控制系统硬件在环仿真平台体积大、重量大,难以满足控制器在外场测试、实验的要求,设计便携式硬件在环仿真设备。普通硬件在环仿真平台,发动机模拟功能和飞控模拟及监控功能分别使用一台工控机。为了实现便携式,综合这两个功能于一台高性能便携式PXI工控机。设计便携式信号调理箱、传感器模拟和执行机构模拟方法组成平台的硬件系统;使用LabWindows/CVI的多线程方法,提高软件实时性,设计平台的软件系统;使用系统辨识法设计APU起动停车模型,使用部件法设计APU稳态工作模型;组成硬件在环仿真平台。便携式仿真平台与电子控制器联合进行APU起动、稳态运行、停车等工作模式的仿真试验,仿真试验结果表明:该平台能够稳定、实时模拟APU工作状态。 相似文献
20.
M. Yasin Akhtar Raja Abdullah Al-Dwayyan Yang Cao Charlie X. Wang 《Optics & Laser Technology》2002,34(2):129-134
We have investigated the packaging introduced feedback and resulting variations in the characteristics of Vertical-cavity surface-emitting lasers (VCSELs). An integrated test and characterization method was developed for both the packaged and bare dies as well as on-wafers chips. Using an ‘integrated test bench (ITB)’ for characterization, packaged and ‘un-packaged’ VCSELs from multiple sources were studied. ITB was used to monitor and measure simultaneously several beam-parameters under various bias conditions including both dc and high-speed pulsed pumping at room-temperature, or at higher-/lower-temperatures that are thermo-electrically controlled. Typical beam parameters included state of polarization (SOP), transverse (spatial) modes, wavelength spectra, and output power. A common observation was that majority of devices are affected by the presence of optical windows capping the package. A shift in longitudinal mode was noticeable in packaged versus ‘un-packaged’ (window-removed) devices. But, SOP and transverse modes in various devices are affected severely and in an unpredictable fashion. 相似文献