共查询到16条相似文献,搜索用时 171 毫秒
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水下无线光通信(UOWC)具有保密性好、容量大、传输速度快等优点,可应用于水下信息传输、资源勘查等领域,通信链路的快速建立和持续稳定是水下无线光通信实际应用的基本条件。在平台扰动和海水信道杂质干扰的条件下,如何实现远距离的快速对准是水下无线光通信必须解决的问题。针对水下无线光通信过程中系统发射端和接收端之间的链路由于干扰问题引起底层平台不断移动而无法对准的问题,搭建了一个基于激光二极管(LD)的水下无线光自动对准系统,该系统具有自动对准控制的特点,即系统在底层平台移动的情况下,依然可以实现链路的对准。 相似文献
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水下无线光通信具有的高带宽、低时延等特点,已成为水下通信的可行选择。系统发送端光源由6只绿光发光二极管(LED)构成阵列,接收端由3只光电倍增管(PMT)构成阵列,形成了6×3的多输入多输出(MIMO)传输方式。在室内10 m水槽水下信道下,实现了1 Mbps的信息传输速率。通过MATLAB软件对接收平面光功率分布仿真,最大值为?35.8 dBm。此外,测试了PMT阳极输出电压波形,并推导出阴极电流波形。理论计算得出信噪比为19.4 dB,理论误码率约为1.1×10?5。所选PMT模块理论上最小接收功率可低至1.5×10?9 W,体现出极高的探测灵敏度。最后,通过蒙特卡洛(Monte Carlo)数字仿真说明,在信噪比25 dB可达到约35 bit·s-1·Hz-1的信道容量。 相似文献
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自由空间光通信网络拓扑优化控制可以降低网络传输延迟,提高通信速率,提出基于平均辐射光功率调节的自由空间光通信网络拓扑自适应控制方法。构建自由空间光通信网络的光传输和信道模型,结合光学度量的方法分析光通信网络的辐射功率、辐射通量以及光通量参数,采用光谱光视度量的方法,进行自由空间光通信网络脉冲幅度调制,采用强度调制和直接检测的方法,实现自由空间光通信的平均辐射光功率调节。根据反馈调节和前置补偿的方法,构建等效自由空间光通信网络拓扑结构模型,实现光通信网络的信道均衡控制和视距链路自适应增益调节。测试表明,该方法提高了信道增益,安全传输速率较高。 相似文献
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N/A 《激光与光电子学进展》1977,14(8):20
硏究与发展高速光探测器是为了探测由激光器、发光二极管射出的几毫微秒以下的短光脉冲,现在它被广泛用于使用激光器和发光二极管的光通信装置上。高速光探测器有光电倍增管和使用半导体的光电二极管、雪崩光电二极管。光电倍增管是利用外光电效应和二次电子倍增效应的具有内放大作用的光探测器。 相似文献
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面向多路射频模拟信号的高线性传输需求,基于强度调制-直接探测的原理,提出了基于波分复用技术的模拟射频光传输方案;利用高线性度模拟直调半导体激光器、波分复用器、模拟光电探测器,设计了基于微波光子技术的波分复用射频光传输链路,该链路具有低串扰、低失真、链路增益可调等性能。利用该链路进行了直调激光器、驱动控制电路、射频光发射模块和光接收模块的样机研制。对所研制出的样机进行了实验测试。测试结果表明:通道增益可在-30~10 dB调谐,通道内基波与二次谐波抑制比高于50 dB,相邻及非相邻通道间射频串扰均低于60 dB,相位一致性在±5°以内。针对不同的信号输入功率,在线调整链路增益,改善链路的信噪比或非线性失真效应。设计和研制的样机可用于低频段射频信号的光纤传输。 相似文献
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研究了光载无线通信(RoF)链路中掺Er3+光纤放大器(EDFA)对链路噪声系数(NF)和增益的影响,同时采用自制的具有高响应度、高饱和功率特性单载子传输光电探测器(UTC-PD)作为链路光电转换器件,在不以NF为代价的同时使得链路增益性能获得大幅提升。实验表明,对于由LD、马赫-曾德调制器(MZM)、EDFA、光滤波器(OBPF)和UTC-PD组成的RoF光链路,在LD输出功率为17dBm、UTC-PD的输出平均光电流为60mA时得到最低链路NF为30.3dB,相比不含EDFA的基本链路在LD输出光功率同为17dBm时的NF略小0.4dB;同时链路增益高达15.5dB,相比基本链路大幅提升了41.3dB。 相似文献
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Monte Carlo–based channel estimation and performance evaluation for UWOC links under geometric losses 下载免费PDF全文
Rabia Qadar Mumraiz K. Kasi Sara Ayub Faisal A. Kakar 《International Journal of Communication Systems》2018,31(6)
Underwater wireless optical communication has been studied and proposed as a potential technology for various underwater applications including monitoring and surveillance using wireless sensor networks. In this context, we present a statistical model using an exhaustive Monte Carlo approach for an underwater wireless optical communication link between sensor nodes in a data mulling environment. This work provides insights into the science of photon transport underwater, its utilization in a communication system, evaluation, and optimization of underwater communication. We characterize the temporal channel behavior taking into account multiple scattering of photons involving the constraints of detector aperture diameter, field‐of‐view (FOV), and link distance for an aligned point‐to‐point link. We analyze the designed model in terms of total received power and bit error rate for clear ocean waters. Our simulation results show that the detector aperture and FOV has an impact towards a successful communication in the distance from 5 to 20 m. In addition, results show that the FOV is an affecting factor only in the presence of larger aperture sizes of the detector. 相似文献
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随着海洋探测研究的不断深入,水下无线通信技术已成为制约其发展的关键。针对水下高速、远距离无线通信的需求,设计了一种面向海洋商用的水下双向链路通信系统。系统在发射端采用激光LD及LED双发射源,提出了双发射光源的系统设计方案,并通过设计相应的驱动电路验证了方案的可行性;在接收端利用5 mm大面积APD及高灵敏度PMT双接收探测器接收光信号,适用于远距离、高速通信;系统的信息处理部分由FPGA完成,通过网络通讯方式与PC端进行信息交互;最后完成整个系统设计并进行了商用工程化。开展的水下模拟实验表明,系统在通信距离5 m、误码率10?7时,通信速率可达60 Mbps;在远距离通信60 m、误码率10?7时,通信速率达10 Mbps。 相似文献
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This paper has presented our interesting in wireless underwater communications for different ocean water types. Recent interest in ocean exploration has brought about a desire for developing wireless communication techniques in this challenging environment. Due to its high attenuation in water, a radio frequency (RF) carrier is not the optimum choice. Acoustic techniques have made tremendous progress in establishing wireless underwater links, but they are ultimately limited in bandwidth. In traditional communication systems, constructing a link budget is often relatively straight forward. In the case of underwater optical systems the variations in the optical properties of ocean water lead to interesting problems when considering the feasibility and reliability of underwater optical links. The main focus of this paper is to construct an underwater link budget which includes the effects of scattering and absorption of realistic ocean water. As well as we have developed the underwater optical wireless communication systems to have shorter ranges, that can provide higher bandwidth (up to several hundred Mbit/s) communications by the assistant of exciting high brightness blue LED sources, and laser diodes suggest that high speed optical links can be viable for short range application. The received signal power, signal to noise ratio, bit error rate, transmitted signal bandwidth, and transmission bit rates are the major interesting parameters for different ocean water mediums as a criteria of the best signal transmission characteristics of short wireless optical communications over wide range of the affecting parameters. 相似文献
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The detection of low-level optical frequency radiation, such as that encountered in laser communication systems, is often accomplished with a photomultiplier tube. The photomultiplication process, however, is itself a random process. In this paper a formula for the statistics of the number of electrons afterk stages is derived in the form of a recurrence relation. A Polya distribution is assumed as a model for each stage, and the probability of error for a laser communication system is examined in terms of the Polyab -parameter and the gain per stage. A simple closed-form expression for the decibel loss as a function of the photomultiplier parameters is also derived. 相似文献