Experimental optimization of an erbium-doped super-fluorescent fiber source for fiber optic gyroscopes

Double-pass forward and double-pass backward erbium-doped super-fluorescent fiber sources(EDSFSs) were combined in one configuration.A 980 nm laser diode pumped the same erbium-doped fiber from both directions using a coupler as a power splitter.The double-pass configuration was achieved by coating the fiber end face.Firstly,an optimal fiber length was found to obtain a high stability of output light wavelength with pump power, and then 1530/1550 nm wavelength division multiplexing was used for spectrum planarization,which expanded the bandwidth to more than 22 nm.The final step was a test of temperature stability.The results show that the rate of the central wavelength change kept to below 3.5 ppm/℃in the range of -40 to 60℃and 1-2 ppm/℃in the range of 20-30℃.Considering all the three factors of the fiber optic gyro applications,we selected 80 mA as the pump current,in which case the central wavelength temperature instability was calculated as 2.70 ppm/℃, 3 dB bandwidth 22.85 nm,spectral flatness 0.2 dB,output power 5.17 mW and power efficiency up to 9.92%.This experimental result has a significant reference value to the selection of devices and proper design of ED-SFSs for the application of high-precision fiber optic gyroscopes.     

机载雷达和ESM系统误差下的融合跟踪

针对机载雷达和ESM系统误差下的融合跟踪问题,提出了一种基于数据压缩和间歇式雷达管理的异类传感器融合跟踪算法。首先通过数据压缩的方法对雷达和ESM间断量测进行融合跟踪,接着在此基础上利用融合跟踪中预测协方差和预定门限的比值对雷达实施开关机处理,以求有效提高作战飞机在融合跟踪中的抗干扰和反侦察能力。仿真结果表明,该算法可有效地实现系统误差下的目标融合跟踪。     

应用于软件无线电接收机中的无源下变频混频器

设计了一个应用于软件无线电接收机中的宽带无源下变频混频器,采用SMIC 0.13μm RF工艺实现,芯片面积0.42 mm<'2>.测试结果表明:在1.2 V电源电压下消耗了9 mA电流,工作频段0.9～2.2 GHz,电压转换增益17 dB,HP3 6～7 dBm,IIP2 40～42 dBm,DSB NF 17.5...     

水热法制备K0.5Bi0.5TiO3陶瓷粉体及其介电性能研究

采用水热法合成了K0.5Bi0.5TiO3(KBT)无铅压电陶瓷粉体.运用X线衍射(XRD)分析了KOH浓度及反应时间对产物物相的影响;利用扫描电镜(SEM)和透射电镜(TEM)观察研究了粉体的形貌.结果表明,增大碱浓度(4～12 mol/L)和延长反应时间都有利于KBT纳米粉体的合成.在220℃,KOH的起始浓度12 mol/L水热合成48 h的纯KBT相呈立方形结构,晶型规整,晶粒尺寸约为100nm.由水热法制备的粉体在1060℃烧结,获得介电损耗为0.05的致密压电陶瓷材料.     

Simulations and experiments for optimal deployment of an RFID‐based location‐aware system

The proliferation of communication and mobile computing devices and local‐area wireless networks has cultivated a growing interest in location‐aware systems and services. An essential problem in location‐aware computing is the determination of physical locations. RFID technologies are gaining much attention, as they are attractive solutions to indoor localization in many healthcare applications. In this paper, we propose a new indoor localization methodology that aims to deploying RFID technologies in achieving accurate location‐aware undertakings with real‐time computation. The proposed algorithm introduces means to improve the accuracy of the received RF signals. Optimal settings for the parameters in terms of reader and reference tag properties were investigated through simulations and experiments. The experimental results indicate that our indoor localization methodology is promising in applications that require fast installation, low cost and high accuracy. Copyright © 2009 John Wiley & Sons, Ltd.     

电信套餐资费配置研究

针对电信套餐资费人工配置周期长、效率低等现状,提出一种模板化的资费配置体系,采用预定义资费模板和自动化加载业务参数的方法,提升资费配置效率。针对集团级集约销售品进行了验证,并对套餐其他配置内容进行了扩展。     

利用ISE-TCAD分析和设计SCR结构的静电保护电路

传统的ESD保护电路设计主要基于尝试性和破坏性的实验,这种方法不利于产品的推出[1]。文中提出使用ISE-TCAD工具对ESD保护电路进行模拟和优化,以快速地获取面积参数。并以某一典型0.6μmCMOS工艺的可控硅整流器(SCR)结构为例,进行ESD人体放电模型的模拟和面积估算,达到了缩短设计周期和增加设计成功率的目的。     

iRGRR/PM：一种新的高速crossbar分组调度策略

iRGRR(iterative Request-Grant-based Round-Robin)算法是一种输入排队crossbar调度算法,具有硬件易实现、可扩展性强、性能优良等优点。在此基础上,该文提出一种新的高速crossbar分组调度策略iRGRR/PM(iRGRR with Packet Mode),可以更好地支持IP分组的调度,能够被应用于高速、大容量的路由器中。与iRGRR算法相比,iRGRR/PM简化了分组输出重组模块的设计,并且提高了crossbar的带宽资源利用率。文中简单分析了两种算法间的分组时延关系,并进行了详尽的仿真研究。结果表明：在相同条件下,iRGRR/PM算法具有更高的吞吐量,尤其在非均匀业务流下能获得接近100%的吞吐量;调度长分组时,iRGRR/PM算法具有更好的时延性能。     

MIMO-CDMA系统的分数间隔空频均衡接收方案

该文提出了两种适用于宽带单载波多用户MIMO-CDMA系统下行链路的分数间隔空频均衡接收方案,并进行了理论推导。第1种接收方案采用分数间隔空频均衡器对MIMO频率选择性衰落信道进行均衡,从而恢复了扩频码的正交性,减小了码间干扰和共道干扰。第2种方案在假设接收端已知各用户扩频码的前提下,将分数间隔空频均衡器与频域并行干扰消除器结合,能够进一步消除天线间干扰,提高系统性能。仿真结果表明,这两种分数间隔空频均衡接收方案都比传统的频域均衡接收方案在性能上有很大的提高,并且复杂度也比较低。     

Performance evaluation on a double‐layered satellite network

How to evaluate the performance of satellite networks is a prerequisite to the construction of satellite networks, and is also one of challenges in the researches on satellite networks. In this paper, generalized stochastic Petri net (GSPN) models are presented to carry out the performance analysis of a double‐layered satellite network. Firstly, the GSPN model of a double‐layered satellite network is simplified by proper analysis. Then, two sets of experiments are conducted to analyse the performance of the satellite networks, and show that the double‐layered satellite network outperforms single‐layered ones on the heavy traffic load. Finally, the feasibility and effectiveness of the proposed approach is verified by simulation experiments. Copyright © 2005 John Wiley & Sons, Ltd.