共查询到18条相似文献,搜索用时 922 毫秒
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星间相干光通信技术的发展历程与趋势 总被引:5,自引:0,他引:5
对星间相干光通信体制和IM/DD体制进行了对比分析,总结了相干体制应用于卫星光通信的优势。介绍了国内外星间相干光通信的研究历程、目前的技术水平和发展趋势。 相似文献
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本文首先扼要介绍了现行的光强度调制/直接检测(IM/DD)方式光通信及其复接体制,接着讨论了光复用技术、相干光通信、光孤子通信、主动光纤、光纤放大器、全光纤通信以及量子光通信等光纤通信前沿领域的基本概念。最后指出,光通信新制式的研究,将挖掘出光纤通信的巨大潜力,为人类进入信息社会展示更加美好的前程。 相似文献
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传统的光纤通信系统采用单一波长的强度调制一直接检测(IM/DD)方式,经光—电—光转换对劣化的信号进行再生中继。随着光电子器件和系统技术的发展,出现了各种延长中继距离、扩大通信容量的新技术,这里主要介绍已实用化的直接光放大技术光波分复用技术和具有良好应用前景的外差式相干光通信技术。 相似文献
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卫星相干光通信是卫星通信中最具潜力的选择.简述了相干光通信的原理和优势,全面介绍了卫星相干光通信的研究历程、现状和发展趋势. 相似文献
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对开关键控(OOK)强度调制直接检测(IM/DD)方式的无线光通信接收发射系统的光电信号进行分析,并使用最大后验概率(MAP)方法确定判决阈值。将对数正态分布作为湍流信道上光强闪烁模型,建立了系统误码率与湍流强度、光源相干参数、激光发射器光功率等系统参数之间的定量关系。采用部分相干光作为信号光能降低光源相干度,有效抑制湍流效应。计算结果表明:在一定条件下,湍流强度改变0.5个量级系统误码率相差6-8个量级,并且最优源相干参数可以通过计算得到,其对应的部分相干光最有利于提高通信系统性能。 相似文献
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舰光 《大气与环境光学学报》1994,(4)
卫星间光通信的技术与现状卫星间光通信的特点与作用卫星间光通信是卫星间大容扩通信的发展方向。与卫星间的微波通信相比,卫星闪光通信系统具有装置小、重量轻、抗电磁干扰、通信容量大等优点,因而光通信将成为未来卫星间通信的重要手段。卫星间光通信系统有以下几个特... 相似文献
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探讨了采用时间透镜来实现时间-频率间的傅里叶变换原理,给出了时间透镜的系统构成,设计了基于时间透镜的正交频分复用系统。仿真实验表明,基于时间透镜的高速光纤频域IM/DD传输系统,在传输速率大于10Gb/s时,比传统的IM/DD系统抗色散性能优势明显、性价比高且实用性强。 相似文献
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《Lightwave Technology, Journal of》2009,27(11):1503-1513
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以目前技术最为成熟、应用最为广泛的强度调制/直接检测(IM/DD)体制的自由空间激光通信体制为例,利用自主研发的无线激光通信系统,采用漫反射的方法,研究了小功率脉冲激光对自由空间激光通信的干扰效果。利用不同调制频率、不同脉宽的半导体激光器和固体激光器分别进行了多次激光干扰实验,证明了干扰的可行性,得出了调制频率、脉宽与干扰效果的关系,并结合自由空间激光通信原理和通信设备的工作流程对实验现象加以解释和分析,提出了低功率脉冲激光对通信系统实现干扰的条件。 相似文献
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This paper focuses on transmit beamforming for multiple-input multiple-output optical wireless communication (OWC) systems with intensity modulation and direct detection (IM/DD). OWC with IM/DD requires the transmitted signals to be nonnegative, for which existing beamforming schemes developed for radio frequency systems cannot be applied directly. We propose effective schemes for OWC over frequency flat and frequency selective channels. For frequency flat fading, the property of the beamforming vector is derived. For frequency selective fading, bit-error rate performances of the proposed scheme with zero-forcing and minimum mean-square error frequency domain equalization receivers are derived, and a suboptimal beamforming vector for frequency selective fading channels is proposed. Compared with asymmetrically clipped optical orthogonal frequency division multiplexing based frequency domain beamforming, the proposed scheme needs much less feedback information and has a better error performance. 相似文献
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Turbo-coded optical PPM communication systems 总被引:3,自引:0,他引:3
A number of parallel concatenated convolutionally coded (PCCC) photon communication systems is introduced and investigated. It is assumed that the optical channel is an intensity modulated (IM) channel and that the received optical signal is detected using a direct-detection (DD) scheme. Two modes of operation are considered. In one scenario, it is assumed that the receiver is limited by shot noise (i.e., negligible receiver thermal noise, or Poisson channel). In the other case, we consider a nonnegligible receiver thermal noise where an avalanche photodetector (APD) is employed to detect the received optical signal. It is also considered that the modulation scheme is the binary pulse-position modulation (PPM). With the aid of the best available upper bounds, the performance of the rate 1/n PCCC encoded optical PPM systems is assessed in terms of the upper bound on the system bit error rate (BER) for the shot-noise-limited IM/DD systems with nonnegligible background noise and for the thermal-noise-limited systems with APD detectors when a uniform interleaver is used. Numerical results for the rate 1/3 PCCC encoded PPM channels are presented. The numerical results demonstrate the enormous potential of this novel coding scheme in enhancing the performance of the aforementioned optical channels by a sizeable margin across the board 相似文献
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We investigate the performance of coherent analog optical links employing amplitude modulation (AM), phase modulation (PM), and frequency modulation (FM). The performance of these coherent links is compared to that of AM direct-detection (DD) links. The signal-to-noise ratios, nonlinearities, and-spurious-free dynamic ranges (SFDR's) of the foregoing links are evaluated. We calculate the SFDR for links using DFB and Nd:YAG lasers with typical linewidths of 10 MHz and 5 kHz, respectively. The performance of PM and FM links is dominated by phase noise above a critical value of received optical power. For a linewidth of 10 MHz, and SFDR's of PM and FM links are 30 and 31 dB, respectively, for a received optical power above -27 dBm in a 1 GHz bandwidth. For a linewidth of 5 kHz, the corresponding SFDR's above a received power level of 0 dBm are 51 and 53 dB. The performance of DD and AM links is dominated by RIN above a critical value of received optical power. For a RIN level of -155 dB/Hz, the SFDR's of DD and AM links are 49 and 47 dB, respectively, for a received optical power of 10 dBm in a 1 GHz bandwidth. The SFDR's of the DD and coherent links used for transmission of subcarrier-multiplexed (SCM) signals are also derived. We evaluate target laser parameters needed by a number of different applications. For AM video and antenna remoting applications, linewidths of <1 and <3 kHz are required to use PM and FM links, respectively. For FM video, linewidths of <150 and <350 MHz are required to use PM and FM links. For SCM digital applications, linewidths of <80 and <200 MHz are required to use PM and FM links. The paper concludes with a discussion of system implementation issues, including linearization, optical frequency modulation, balanced receivers, and IF issues 相似文献
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