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An incoherent receiver is derived for the heterodyne optical channel under the assumption of Phase coherence at the start of each transmitted sequence. The receiver is optimal in the limit of small bit intervals with respect to the coherence time of the laser oscillators, and reduces to that proposed by Jeromin and Chan [1] when no initial phase coherence is present. Computer simulations indicate that the small amount of performance improvement obtained by resolving an initial phase uncertainty may not justify the extra complexity needed, for the data rates currently considered. 相似文献
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Design considerations for an optical spatial tracking system for both coherent and noncoherent heterodyne detection are addressed. Heterodyne detection systems are much less susceptible to background radiation and device noise than conventional direct detection systems. In addition, the angle discriminator profile in a heterodyne detection system can be tailored via the local oscillator spatial distribution. An optimal LO distribution is described and its performance is compared to some Suboptimal distributions. It is shown that an ideal quadrant detector can achieve near optimal performance, since the LO effectively acts like a continuum of detectors. Cramer-Rao tracking bounds and other performance criteria are given under the conservative assumption that the angular process to be tracked is a single-pole process. The method used is directly applicable to other types of angular processes. Experimental verification of some of the basic concepts is presented. 相似文献
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《固体电子学研究与进展》2018,(2)
介绍了一种应用于5.8GHz频段的专用短距离无线通信接收机前端,采用超外差低中频正交架构,通过合理规划接收机前端两次混频的频率可以有效解决镜像干扰和两条正交通路的失配。该前端包括低功耗的噪声抵消的低噪声放大器,其负载采用电容电感谐振电路,谐振频率可调,并具有一定的工艺稳定性。第一次混频采用电压模式无源混频器,第二次混频采用电流模式无源混频器。提出了一种简单有效的用于混频开关的偏置电路,射频混频开关采用反馈的方式确定偏置电压,中频混频开关的直流电压利用跨阻放大器的输出共模电压分压得到。芯片于TSMC 180nm工艺下流片,前端电路的有效面积为0.1mm2,整个链路的接收灵敏度达到-65dBm,接收数据率可以达到256kbps,在1.8V的工作电压下,消耗10.8mA的电流。 相似文献
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应用广义的惠更斯-菲涅耳原理及改进的Rytov方法,采用基于Gamma-Gamma光强概率分布的海洋湍流信道模型,得到了中断概率解析式.并在此基础上对各向异性海洋湍流高斯光束外差式差分相移键控(DPSK)调制的中断概率性能进行了研究.仿真分析了不同的各向异性海洋湍流下各种海洋湍流参数(温度与盐度波动对功率谱变化贡献之比、单位质量流体动能耗散率、均方温度耗散率)、传输距离、DPSK调制的数据传输速率对中断概率的影响.为降低高斯光束DPSK调制下的中断概率、提高通信质量及可靠性提供了理论依据. 相似文献
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Coherent heterodyne detection in optical communication is degraded by phase instabilities present when a semiconductor laser is used as a local oscillator. Postdetection processing that accounts for these instabilities is suggested, based on a diffusion-process model for oscillator instabilities and a maximum-likelihood sequence-estimator of information symbols modulating the received light. 相似文献
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为了将光通信一些优越性能应用于空间光探测、空间光通信和民用个人通信,在目前光纤只有非常小的数值孔径的情况下,需要对微弱空间光信号进行厂角接收,以便使接收角度达数十度、以致半个空间的光信号能进入光纤接收系统。然后可以对其中光信号进行光放大和处理。文章将空间光厂角接收馈源分为传统接收馈源和耦合入纤接收馈源两大类,着重于讨论后者。前者由于受制于光学系统和传统滤波器对视场角的限制,其灵敏度和视场角难以同时得到提高。而后者有望解除这些限制,真正实现对微弱空间光信号的非扫描式广角接收,应该是今后的发展方向,具有广泛应用前景。空间光厂角接收的实现将有力促进空间光通信、个人通信和光探测技术的发展,加大空间通信的带宽,对未来通信将产生不可估量的影响。 相似文献
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《Microwave Theory and Techniques》1981,29(6):557-561
A low-noise heterodyne receiver for the 200-350-GHz region has been developed and used in astronomical observations. Two-room temperature mixers cover this range, with local oscillator (LO) power provided by frequency multiplied klystrons. A single crossed waveguide multiplier design covers the entire range, and is found to provide adequate output power by either doubling or tripling. Signal-LO diplexing is done with a quasioptical diplexer based on a Martin-Puplett interferometer. The best system sensitivities obtained with the two mixers have been 2100 K SSB at 242 GHz and 2900 K at 285 GHz. 相似文献
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针对应用于850nm光通信中的10/100Mbit/s收发器,提出采用0.5μm标准CMOS工艺对其光接收芯片实现Si基单片集成。整体芯片面积为0.6mm2,共集成了一个双光电二极管的(DPD)光电探测器和一个跨阻前置放大电路,功耗为100mW,并给出了具体的测试性能结果。结果表明,在850nm光照下,光接收芯片带宽达到53MHz,工作速率为72Mbit/s。重点介绍了DPD光电探测器的原理和结构,并给出了相应的制造过程和电路等效模型,对整个光接收芯片进行了多种实用性测试,可以满足系统的性能要求。 相似文献
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分析了基于CDMA低轨道卫星移动通信RAKE接收机的误码率性能。在给出郊区环境和城市环境两个 卫星移动通信信道模型的基础上,本文针对郊区环境模型,推导出二进制正交FSK调制方式下,最大比合并RAKE 接收机的系统平均误码率公式,并在不同阴影遮蔽参数条件下,对提出的公式进行了数值分析。 相似文献
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无线光通信调制方式性能分析 总被引:13,自引:3,他引:13
无线光通信的调制方式有多种,但缺少综合系统的分析。在详细地分析了脉冲位置调制(PPM)、数字脉冲间隔调制(DPIM)和双头脉冲间隔调制(DH—PIM)等调制方式符号结构的基础上,比较了各种凋制方式的平均发射功率和带宽效率,并在给定模型下分析了误时隙率。通过分析得出DPIM和DH—PIM更具有优势,更适合于未来无线光通信系统。 相似文献
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The low dispersion and low attenuation properties of fibers between 1.3 μm and 1.6 μm make them more attractive for optical fiber transmission applications. In the absence of efficient avalanche photodiodes in this wavelength range, considerable research and development efforts on detectors as well as on the lownoise amplifier devices have been carried out. This paper reviews the present status of optical detectors and low-noise amplifier devices and discusses the low-noise amplifier design process by using a couple of examples at DS-1 and DS-4 bit rates. 相似文献
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A. Waksberg 《Journal of Infrared, Millimeter and Terahertz Waves》1999,20(6):1059-1071
The field of view of optical heterodyne systems are usually limited by a simple criterion- namely, that ARΩR ? λ2, where AR is an effective aperture, ΩR the corresponding field of view and λ the optical wavelength. This paper will demonstrate that with a simple change of systems geometry and the possible use of array detectors, this severe restriction can be alleviated considerably and, in some cases, eliminated. Both coherent sources and thermal radiation sources are considered. This might suggest that heterodyne systems that were eliminated in the past because of that criterion alone, could turn out to be, not only possible, but even advantageous compared to other techniques. 相似文献
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无线光通信调制技术的性能分析 总被引:4,自引:0,他引:4
在对五种典型大气无线光通信调制方式——OOK、PPM、DPPM、DPIM和DH—PIM的调制结构进行分析的基础上,结合大气无线光信道特点,分析比较了这五种调制方式的平均发射功率、传输容量和误时隙率。理论分析与仿真结果表明:DPPM、DPIM和DH-PIM更具有优势,更适合于未来无线光通信系统。 相似文献