查询词典 antenna switch

Directing the develop state of Community Antenna Television network and users request of high-speed connection, access Internet over Cable Modem and Community Antenna Television network , as one of the new high-speed connection mode, are being attent more and more .

针对有线电视网络的发展现状和用户高速接入的要求，通过Cable Modem和有线电视网络访问Internet，作为新兴的高速接入方式之一，正受到越来越多的关注。

Television signals can be transported in three ways: broadcast via radio waves using ground antenna, by the coaxial tree network of the community antenna TV network or recently via a satellite, using the so-called direct broadcast system DBS

这个接口之所以如此称呼，是因为无论在多长的时间区间里发送的数据和接收的数据是不同步的，因而没有必要采用特殊的手段使发送器和接收器的时钟同步。

Television signals can be transported in three ways: broadcast via radio waves using ground antenna,by the coaxial tree network of the community antenna TV network or recently via a statellite, using the so-called direct broadcast system.

电视信号可以种方式传送：利用地面天线的无线广播方式；用公用天线电视网的同轴电缆树状网络传送；近来人们又利用卫星，通过被称为直接的广播系统来传送。

Television signals can be transported in three ways: broadcast via radio waves using ground antenna, by the coaxial tree network of the community antenna TV network or recently via a satellite, using the so-called direct broadcast system.

电视信号可以种方式传送：利用地面天线的无线广播方式；用公用天线电视网的同轴电缆树状网络传送；近来人们又利用卫星，通过被称为直接的广播系统来传送。

A,顺序法 Television signals can be transported in three ways: broadcast via radio waves using ground antenna, by the coaxial tree network of the community antenna TV network or recently via a statellite, using the so-called direct broadcast system.

电视信号可以种方式传送：利用地面天线的无线广播方式；用公用天线电视网的同轴电缆树状网络传送；近来人们又利用卫星，通过被称为直接的广播系统来传送。

With the overview of present MIMO antenna research, the thesis brings forward a new kind of polar diversity antenna array applied in MIMO base stations, which elements are planar printed dipoles. The beamforming technology is used to obtain a particular type of elevation pattern, which has square cosecant characteristic.

本文在对目前MIMO 天线领域的研究动态进行概述的基础上，结合基站的自身特点，提出并实现了一种新型的基站极化分集波束赋形天线阵列，其阵元为平面印刷偶极子，阵列在俯仰面形成类似平方余割形式的方向图分布。

The main job and contribution of this paper are as follows:Based on narrowband signal processing, we propose a new method for FH signal blind detection and blind parameter estimation. Firstly, compute the cross-correlation function of FH signals from multichannels, then we get the cross power spectral density matrixCSDM Secondly, select the hops of FH signals from the CSDM via processing and analyzing the CSDM, meanwhile reduce the influence coming from noise, fixed frequency signal and other interferences; Lastly, estimating the DOA of every hop and according to the DOA, we can separate the hops, get the number of FH signals and their parameters. Propose a new method for designing the threshold in FH signal detection. This method makes it easy to get the threshold by theoretic computing and it can extremely reduce the interference of non-FH signals.Based on broadband signal processing, we propose a new method for FH signal blind detection and blind parameter estimation. Firstly, get the DOA of the signals by wideband spatial spectrum estimation; secondly, separate the signals by spatial filtering using wideband beamformer; Lastly, we propose two methods for FH signal blind detection and blind parameter estimation, one is for several constant hop-rate FH signals whose dwell-time are different and another is for a single FH signal whose hop-rate is alterable.By employing spatial interpolation in broadband signal beamforming, it can reduce the number of antenna elements and corresponding RF modules, A/D converters, etc. It can also eliminate the mutual coupling between antenna elements while getting the narrower main beamwidth and lower sidelobe level.

本文的主要研究工作和贡献如下：●提出了一种基于窄带处理的FH信号盲检测和参数盲估计的实现方法，即首先求出多路信号之间的互相关，进而得到互功率谱密度矩阵，然后通过对CSDM进行对折处理来抑制噪声、定频信号及其他干扰的影响，并将所有属于FH信号的hop(每一跳的驻留时间在时频图上持续的线段)从CSDM中筛选出来，最后用阵列信号处理中的到达方向估计理论在频域中估计出各个hop的方向参数，利用方位信息完成FH信号分离并得到FH信号的数目及其各自的参数集；●提出了一种确定FH信号检测门限的策略，该策略不仅使得检测门限能够通过理论计算得到，而且还显著地抑制了非跳频信号的干扰，从而能有效地检测出FH信号；●提出了一种基于宽带处理的短波FH信号盲检测和参数盲估计的实现方法，即首先利用宽带空间谱测向技术得到接收信号的DOA，然后采用宽带波束形成技术对特定方向进行空间滤波，实现多个信号的分离，最后分别提出了两种FH信号的盲检测和参数盲估计方法，第一种方法适用于空间某个特定方向上存在着几个驻留时间不同的恒跳速FH信号和其他干扰信号的混合信号，第二种方法适用于空间某个特定方向上仅含一个可变跳速的FH信号和噪声的混合信号；●将空间插值的概念和宽带波束形成技术结合起来，提出了一种基于频域处理的宽带恒定束宽的波束形成方法。

Two kinds of antenna, Vlasov antenna and COBRA, which are suitable for radiating cylindrically symmetric modes, are investigated through theoretic analyses, numerical calculations and experiments.

本文从理论推导、数值计算和实验等方面研究了两类可以直接辐射轴对称模式的天线—Vlasov天线和COBRA天线。

Feeding patterns of antenna array are researched and feeding network is designed. Three-unit and four-unit models for the cylindrically conformal microstrip antenna array are set up and their directivities are simulated respectively. Through the comparison of the simulation results, the four-unit array is proved to be feasible.

对天线阵列的馈电方式进行了研究，设计了天线阵列的馈电网络，建立了三单元和四单元柱面共形微带天线阵列模型，对方向性分别进行了仿真分析，比较仿真结果，选用了满足工程需要的四单元阵列。

Different antenna frequency have different using, underground utilities or dewater box can use antenna frequency 100 MHz with 250 MHz.

4不同天线频率有其适用性，地下管线及箱涵可搭配天线频率100 MHz和250 MHz相互使用。

Listen,point and check your answers.

听，指出并且检查你的答案。

Warming needle is one of effective treatment methods for knee arthralgia aggravated by cold,and it is simple,safety,so it should be developed in clinical acupuncture and moxibustion extensively.

但以本院科针灸门诊在2005年1月—2006年6月期间共收治膝痛患者100余例，经过临床的诊断后，其中施以温针治疗的48例，疗效显著，报道如下。1临床资料本组病例48