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“空中之星”无线本地环路美国UT斯达康的AirStar“空中之星”WLL系统是当前各种WLL系统产品中的佼佼者.它是UT斯达康的AN2000综合接入网系统与PHS技术集成的无线本地接入网系统.AN2000与中央交换局连接,主要担任数字复用、光纤传输、... 相似文献
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介绍AN-2000是一个比较完善的综合接入系统,现已能提供POTS,DDN、2/4W E&M,ISDN接口(2B+D,308+D),子速率复用等综合业务接入,同时新的业务接入模块也正在不断推出;并且将AN-2000与交换机远端模块的几个方面进行了比较。最后简介AN-2000与F-150、S-1240的对接实验。 相似文献
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本文介绍了VSAT通信技术的现状及其在解决数话兼容的综合通信系统方面的一些常用体制的方案,并着重介绍一和种数话、传真兼容的综合业务数字卫星通信产品-美国ANDREN VSAT SYSTEMS开发的SWAN VSAT系统。 相似文献
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本文式图对当前移动通信发展中的几个热点问题联系起来探讨其发展趋势。首先是CDMA的优势2与总是何在。文中指出,CDMA的优势在容量,而问题在于它是功率和干扰受限系统。其次是N-CDMA在第二代和二代半移动通信中的应用前景,预计1997年将见分晓。W-CDMA将在第三代移动通信,即个人通信,例如IMT-2000和UMTS中成为优选方案之一。在未来的信息调整公路中B-CDMA将是解决无线接入的关键技术 相似文献
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由ITU-T 提出的第三代移动通信系统UMTS/FPLMTS(IMT-2000),是工作在2GHz频段上的宽带移动通信系统,计划2000年左右投入试验和运营的标准化。IMT—2000系统模型(图1),采用模块化概念,在交换网络与无线路入网之间定义了一个明确的无线网络接口。该接口允许未来多种无线系统连接到多种现存的核心网络和IMT—2000的核心网络。 无线接入网由无线承载公用功能(RBCF-Radio Bear Common Functionality 和无线传输特定功能(RTSF─Radio Transmission SpecificFunctionality)两个部分组成。RBCF完成控制和传输功能;RTSF完成无线接入技术功能,主要为无线传输技术( RTT─Radio TransmissionTechnology)和无线传输适配功能(RTAF─Radio Transmission Adaptation Functionality)。在交换网一侧,IMT—2000通过合适互通功能或适配功能与现有的核心网络互连。IMT—2000的竞争焦点集中在地面无线传输技术上。 第三代移动通信系统的基本特点 第三代移动通... 相似文献
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研究了AN/TRC-170数字对流层散射通信系统中使用的二频交叠升余弦信号的特点,分析了方波、半余弦和升余弦信号的带宽与能量通过率的关系,得出了该信号形式的最佳频率配置。分析结果说明,AN/TRC-170对流层散射通信设备的窄带和宽度2种波形都实现了无串扰的带内两频无间隔紧密配置,其频率配置是合理的。提出了一种基于FFT/IFFT的数字分路滤波器的实现方案,解决了传统的FIR方法难以在高采样率下实现窄通带、陡过渡带低通滤波的问题,给出了试验结果。 相似文献
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Contributed by UTStarcom 《世界电信》1997,10(5):19-20,27
本文首先讨论了采用接入网新技术进行优化网络结构,改善业务质量,提供综合接入的方法及其原理。另外对美国UTStarcom公司的接入网产品AN2000的结构,应用范围以及与各大厂商交换机采用V5.x接口对接的实验情况进行了简单介绍。 相似文献
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下一代电信网的接入网 总被引:2,自引:0,他引:2
本文介绍了下一代电信网的接入网的定义定界及功能,同时对影响接入网在新时期发展的几个因素进行了分析,最后提出了下一代电信网中接入网设备的功能要求. 相似文献
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Current Navy signal processing requirements range from tens of millions to hundreds of millions of multiply-add operations per second. It is expected that these requirements will increase tenfold within the next ten years. To accommodate these expanding requirements, the Navy is building the Signal Processor (AN/UYS-2). The AN/UYS-2 design is driven by the fact that it is the Navy standard signal processor. Being a stantard, it must satisfy more requirements than just high throughput. It must be programmable, modular, expandable, flexible supportable, reliable and provide this capability for the next 20 years to support existing and future users. In order to make it programmable (and therefore reduce the total life cycle ownership cost), the AN/UYS-2 utilizes a Navy developed signal processing graph language methodology called PGM. The implementation of PGM on AN/UYS-2, provides the AN/UYS-2 user with a convenient and cost effective way of specifying the signal proccessing algorithms to be executed for a given application. The AN/UYS-2 desgin approach is to implement PGM and to develop a modular, multiprocessor that could meet a wide range of air, sea, and shore signal processing applications. In order to meet this requirement, a hybrid control-flow/data-flow architecture was chosen to enable evolutionary technology infusion. VLSI component technology is required to implement the primary processing engine in the architecture. The AN/UYS-2 architecture consists of a variable combination of multiple types of Functional Elements (FEs), a data transfer network, a control bus, and a built-in-test (BIT) control bus. This paper provides a review of AN/UYS-2 basic design and growth potential. 相似文献
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Current Navy signal processing requirements range from tens of millions to hundreds of millions of multiply-add operations per second. It is expected that these requirements will increase tenfold within the next ten years. To accommodate these expanding requirements, the Navy is building the Signal Processor (AN/UYS-2).The AN/UYS-2 design is driven by the fact that it is the Navy standard signal processor. Being a stantard, it must satisfy more requirements than just high throughput. It must be programmable, modular, expandable, flexible supportable, reliable and provide this capability for the next 20 years to support existing and future users. In order to make it programmable (and therefore reduce the total life cycle ownership cost), the AN/UYS-2 utilizes a Navy developed signal processing graph language methodology called PGM. The implementation of PGM on AN/UYS-2, provides the AN/UYS-2 user with a convenient and cost effective way of specifying the signal proccessing algorithms to be executed for a given application.The AN/UYS-2 desgin approach is to implement PGM and to develop a modular, multiprocessor that could meet a wide range of air, sea, and shore signal processing applications. In order to meet this requirement, a hybrid control-flow/data-flow architecture was chosen to enable evolutionary technology infusion. VLSI component technology is required to implement the primary processing engine in the architecture. The AN/UYS-2 architecture consists of a variable combination of multiple types of Functional Elements (FEs), a data transfer network, a control bus, and a built-in-test (BIT) control bus. This paper provides a review of AN/UYS-2 basic design and growth potential. 相似文献
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Dorronsoro J.R. Lopez V. Cruz C.S. Siguenza J.A. 《Signal Processing, IEEE Transactions on》2003,51(5):1431-1438
We introduce linear autoassociative neural (AN) network filters for the removal of additive noise from one-dimensional (1-D) time series. The AN network will have a (2M+1)/spl times/L/spl times/(2M+1) architecture, and for M fixed, we show how to choose the optimal L value and output coordinate from square error estimates between the AN filter outputs and the clean series. The frequency response of AN filters are also studied, and they are shown to act as matched band filters. A noise variance estimate is also derived from this analysis. We numerically illustrate their behavior on two examples and also compare their theoretical performance with that of optimal Wiener filters. 相似文献
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利用原子力显微镜(AFM)和扫描电镜(SEM)对磁存储器(MRAM)驱动电路与存储单元--磁性隧道结(MTJ)的连接界面的表面平坦化进行了研究. 原子力显微镜照片表明:磁控溅射沉积的金属铝膜的表面由尺寸约为300nm的颗粒组成,其表面粗糙度约为几十纳米的量级,用统计平均值(均方根值root mean square,RMS)描述约为10nm;在铝膜的表面沉积一层难溶金属Ti或Ta膜以后,可很好地改善过渡层金属表面的平坦化效果. 通过用化学机械平坦化设备(chemical mechanical planarization,CMP) 在小压力和低转速的条件下,可使过渡层金属表面的RMS值达到小于1nm的平坦化效果. 扫描电镜照片的结果也显示:利用光刻胶平坦化,然后通过调节反应离子刻蚀的条件,使刻蚀的过程中对氧化硅和光刻胶的刻蚀速率相等,去掉光刻胶,达到平坦化整个芯片表面的效果. 相似文献