共查询到19条相似文献,搜索用时 171 毫秒
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提出了两种基于光纤光栅以减小ROF(radio over fiber)系统中光纤色散引起的微波功率衰落的方法.第一种为采用窄带光纤光栅滤波实现微波信号的残余边带调制,另一种为采用啁啾光纤光栅实现光纤色散补偿.实验测量并比较了这两种方法与传统双边带调制时ROF系统传输性能的变化.结果表明,窄带光纤光栅和啁啾光栅均能有效减小ROF系统中的光纤色散效应. 相似文献
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分别对基于双边带调制和基于FBG单边带调制的ROF系统中色散所致信号衰减进行了理论分析,并利用软件对两种系统在各种不同条件下的性能进行仿真.结果表明,采用光纤光栅的单边带调制技术可明显提高ROF系统性能.根据仿真结果,提出了选择光纤的方案,为进一步研究ROF系统的传输带宽和传输距离受限问题提供了研究思路. 相似文献
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射频光纤传输系统中色散对数字毫米波信号的影响 总被引:1,自引:0,他引:1
给出了通过采用双边带调制技术来产生下行链路的ROF毫米波数字信号的设计方法:同时对基于数字ROF信号的光纤传输系统的色散影响进行了理论分析和仿真。仿真结果表明:由于光纤色散影响,毫米波信号的接收功率会随传输距离的变化而成周期性的衰减;同时对传输特性影响较大,而且当常规单模光纤中的传输达到90公里以后,还会产生比较严重的影响。 相似文献
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Photonic downconversion (PDC) technique for dense wavelength division multiplexing (DWDM) millimeter-wave-band radio-on-fiber (ROF) uplink systems is investigated. The PDC technique is carried out for a lump of all uplink wavelength division multiplexing (WDM) ROF signals at a central station. Each channel is optically separated, photodetected, and demodulated individually without serious signal degradation due to the fiber dispersion effect. Error-free 25-GHz-spaced DWDM transmission and demultiplexing of two 60-GHz-band, 155-Mb/s differential phase-shift keying (DPSK) ROF signals over 25-km-long standard single-mode fiber (SMF) are experimentally demonstrated. 相似文献
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Transmission characteristics of a CPFSK differential detection system with LD direct modulation are studied by computer simulation. Simulation results show that the optimum wavelength for LD direct modulation CPFSK transmission shifts to a wavelength longer than zero dispersion wavelength because of the phase difference between the intensity and frequency modulation components. A precise investigation of the dependence of optimum total dispersion on several parameters reveals the essential role of the phase difference between intensity and frequency modulation induced by LD direct modulation. The transmission distance allowing a 1-dB power penalty at 10 Gb/s is 117 km for a wavelength 30 nm shorter than the zero dispersion wavelength, while the distance is 183 km for a wavelength 30 nm longer. This indicates that the zero dispersion wavelength shift is 11 nm for 100-km transmission 相似文献
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We have experimentally investigated two different schemes (schemes A and B) to generate optical millimeter-wave using optical frequency quadrupling with a Mach–Zehnder modulator (MZM), and wavelength reuse for uplink connection in the radio-over-fiber (ROF) systems. For scheme A, only one MZM is used for both the optical millimeter-wave generation and signal modulation. For scheme B, two MZMs are used. In this scheme, one of MZMs is used to generate optical millimeter-wave for frequency quadrupling, and another one is used for signal modulation. In both schemes, at the base station (BS), the optical carrier can be reused to carry upstream data and delivered to the central station (CS). By experimentally comparing the performance of downstream and upstream transmission in two schemes, it can be seen that scheme B can overcome the crosstalk between the upstream and downstream signals, but scheme A cannot. Meanwhile we also show that the millimeter-wave generated in scheme B has better quality and is almost robust to fiber chromatic dispersion. 相似文献
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为了抑制ROF系统中的非线性效应,提出了两种基于多臂-MZ调制器的调制技术,从理论上阐述了这两种技术的调制方式和原理,运用Optisystem仿真软件对基于这两种技术的ROF系统分别进行了仿真分析,并与基于传统-MZ调制器的ROF系统进行了比较。结果表明:这两种调制技术有效地抑制了ROF系统的非线性效应,扩大了系统能接受的调制指数范围。 相似文献
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为进一步提高光载无线通信(radio over fiber,ROF)系统中光生毫米波的倍频系数,提出了一种基于4个马赫-曾德尔调制器(Mach-Zehnder modulator,MZM)共同作用的20倍频毫米波信号产生方案。推导了理想情况下倍频方案的产生机理,在仿真实验中,分别分析了非理想因素下调制器直流偏置电压漂移、调制指数、消光比等对系统性能的影响,结果显示,当合理设置各参数的取值范围,其光边带抑制比(optical sideband suppression ratio,OSSR)和射频杂散抑制比(radio frequency spurious sideband suppression ratio,RFSSR)的饱和值高达33.20 dB和27.21 dB;针对基于此倍频方案的ROF系统,对比分析了2.5 Gbit/s数据信号的单双边带调制两种不同传输方式,仿真结果表明,当光纤距离为40 km时,单边带依旧可达无差错传输,降低了传输过程中码间走离效应的影响,增加了系统的传输距离,更适合远距离传输,为微波光子学的发展提供了一种理论依据。 相似文献
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对ROF(radio over fiber,光载射频)系统在应用过程中的调制方式进行了分析,同时通过一系列实验证明单边带调制更适合应用于ROF系统的通信过程。因此,基于闪耀光纤光栅(TFBG,tilted fiber bragg grating)的复耦合模理论对光栅的谱的性能进行了分析和实验,不难发现,经过对TFBG进行特定的设计后,可以将TFBG应用于ROF系统中对双边带信号进行反射或者透射实现单边带调制,这样既减少了输出振幅随着距离的周期性变化,也提高了信号的传输效率和接收灵敏度。 相似文献