微波通信原理--1教学文稿.ppt

,单击此处编辑母版标题样式,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,*,*,*,第一部分,微波通信基本原理,NEC,200674,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,目 录,1微波通信系统简介,2微波通信系统方框图,3微波通信系统数字传输系列,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1微波通信系统简介,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波站,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.1 什么是微波,微波也是无线电波，但它是一个比普通无线电波段的波长更短(频率更高)的波段、故名微波。,微波波段的低频端与普通无线电波中超短波的高频端(波长为1m，频率为300MHs)相毗邻，而高频端则与红外线的低频端(波长为1mm，频率为300GHz)相衔接。,1.2 微波在电磁波谱中的位置,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.2.1 普通,无线电波波段的划分,波段名称,波长范围,频率范围,波段名称,超长波,10,5,10,4,m,3k30k Hz,超低频（ULF）,长波,10,4,10,3,m,30k300k Hz,低频（LF）,中波,10,3,10,2,m,300k3M Hz,中频（MF）,短波,10,2,10 m,3M30M Hz,高频（HF）,超短波,10 1 m,30M300M Hz,甚高频（VHF）,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.2.2 微波,波段的划分,波段名称,波长范围,频率范围,波段名称,分米波,1 m 10,cm,0.3G3G Hz,特高频（UHF）,厘米波,10 cm 1 cm,3G30G Hz,超高频（SHF）,毫米波,1 cm 1,mm,30G300G Hz,极高频（EHF）,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.2.3 微波使用频率：300M Hz to 300G Hz,波长：,1,m1mm,频段：UHF:0.3-1.12G X：8.2-12.4G,L:1.12-1.7G KU：12.4-18G,LS：1.7-2.6 G K:18-26G,S：2.6-3.95 G Ka:26.5-40G,C：3.95-5.85G U:40-60G,XC：5.85-8.2G,波长,10Km,1Km,100m,10m,1m,10cm,1cm,1mm,频率,30KHz,300KHz,3MHz,30MHz,300MHz,3GHz,30GHz,300GHz,LF,MF,HF,VHF,UHF,SHF,EHF,微波频段,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.3 微波的特点和应用,1.,微波在其传播过程中，若所遇物体的几何尺寸大于或可与波长相,比拟时，就会产生反射，波长越短，传播特性越与几何光学相似,(如近于直线传播的持性)。,2.,普通无线电波会被高空的电离层所吸收或被反射回来，而微波则,能够穿过电离层至外层空间。电视广播、卫星通信、宇宙航行，,射电天文学，以及受控热核反应中的等离子体的参数测量等，都,是利用了微波的这一特性才得以实现的；,3.微波的频率很高，因此可利用的频带较宽、信息容量大，从而使,微波通信得到了广泛的应用和发展。,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.利用微波作为载体的通信称为微波通信；,2.由于波长短绕射能力差,必须在无阻挡的视线内传播,才能完成正常通信(视距传输）；,3.基带传输信号为数字信号的微波通信是数字微波通信；,4.设备体积小，安装容易，投资小，见效快；,5.一般基带信号处理在中频完成，再通过频率变换到微波频段；,也可以在微波频段直接调制，但调制限于PSK；,6.微波通信的理论基础是电磁场理论；,1.4 微波通信,的特点,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,1.4.1不同的传输方法,MUX,卫星,光缆,微波,同轴电缆,MUX,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波设备,电话/数据图像等信息,微波设备,电话/数据/图像等信息,A 站,B 站,数字微波点对点传输模型,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波,设备,电话/数据,图像等信息,微波,设备,微波,设备,微波,设备,电话/数据,图像等信息,B站（中继）,C站（端）,中继传输,A站（端）,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波站分类,分类.swf,终端站,中继站,枢纽站,背靠背天线,反射板,有源,无源,再生中继,基带转接.swf,中频中继,中频转接.swf,射频中继,微波转接.swf,分路站,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,一些链路中间被阻挡，且这条链路不是很长，我们通常在靠近其中一个站点的地方找一个无源中转站，利用折射进行无源接力。,T,d,1,d,2,R,无源中继,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,背靠背无源,这种情况往往用大口径天线，天线调整要借助于仪表。,费时较长,近端距离要小于5KM,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,反射板无源,全程自由空间损耗为：,（km）,（km）,其中 a 为反射板有效面积,面积A,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,无源中继站（实物照片）,反射板式无源中继站,Plane reflectors,双抛物面无源中继站,Parabolic reflectors,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,应用范围,宏蜂窝、微蜂窝网络传输,专用网,接入网,临时话音或数据链路,传输线的备份,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波传输通道系统组网图,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,光纤、微波传输方式比较,光 纤,微 波,传输媒介,光纤,自由空间,抗自然灾害能力,弱,强,灵活性,较低,高,建设费用,高,低,建设周期,长,短,传输速率,频带宽、速率高,频带窄、速率低,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,设备连接,0.6m,天线,室外单元(,ODU,),天线抱杆,室内单元(,IDU,),中频电缆(同轴型),Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,天线和馈线（波导）,主电源:,发电机或太阳能,蓄电池,动力房,微波设备,抛物面天线,波导,铁塔,D,100 m,无源反射板,禁航灯,防雷器,机房,A,U,X,E,P,X,Tx,Rx,Tx,Rx,充气机,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,椭圆波导,使用范围:室外安装(波导密封),损耗:通用标准波导,A.dB/米r,F Ghz,100,塑料封装,半刚性铜带椭圆波导,长度:,120 m,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,波导密封单元,马达,告警,(T.S),阀,压缩,输入过滤,0-250mbar,压力表,密封切换,压力启动,最大密封压力,告警压力,干燥济,:50 mbars,:75 mbars,:40 mbars,到波导,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,分体式微波设备系统结构,避雷器,接地装置,地气,ODU,IDU,同轴电缆,接地电阻小于10欧姆,ODU的接地线应接到铁塔的角钢上，其接地电阻小于10欧姆,地线的接地电阻应小于10欧姆,铁塔的接地电阻应小于10欧姆,IDU的接地,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,拉线塔,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,Ga=20lgDa+20lgf+20.4+10lgA,Ga为天线增益(dB)；,Da为天线口径(m)；,f为工作频率(GHz)；,A为天线效率，可取50%70%。,增益：,实例:,D0.6M,F=13GHz,G=35dBi (VHP2-130,35.5dBi),抛物面天线,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,高性能天线:,减小背面辐射,和 副辨辐射 15 dB),风力改善,:,0.,6M,:230 km(64m/s),1.8M :190 km(53m/s),抛物面天线,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,抛物面天线,抛物面反射器,极化r.H,极化.V,天线屏蔽器,(减小背面辐射,和副辨辐射 15 dB),3 dB,58,/R(均匀反射),Gain=10 log 0.55,(,),2R,极化去耦 H/V,XPD,30 dB,2,TRT,R,高性能天线,边围+屏蔽器,+,站点和通信方位角,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,加固杆,天线,可调节杆,固定杆,顶视图,防护罩,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,天线辐射图方向性图,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,天线方向性图,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,天线的极化,线极化：水平极化和垂直极化,（以电场方向为参考）,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,天线参数,频段,天线口径,增益,典型性能,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,传输媒质,大气,链路,时间,高度,气候等。,微波传播必须采用直射波，接收点的场强是直射空间波与地面反射波的叠加。传播媒介质是地面上的低空大气层和路由上的地面、地物。当时间(季节、昼夜等)和气象(雨、雾、雪等)条件发生变化时，大气的温度、湿度、压力和地面反射点的位置、反射系数等也将发生变化。这必然引起接收点场强的高低起伏变化。这种现象，叫做电波传播的衰落现象。显然衰落现象具有很大的随机性。,1.5,衰落,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,衰落类型,1.多径衰落,2.K型衰落,3.波导型衰落,4.雨衰,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,多径衰落,由于折射波，反射波，散射波等多途径传播引起的衰落。多径衰落周期较短一般为几秒。多径衰落又叫频率选择性衰落。合成波的电平比正常传输低称为下衰落，比正常传输高称为上衰落。,地面,大气不均匀,水面,光滑地面,是主要原因,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,K型衰落,由于折射系数（K）的变化，使直射波和地面反射波相干涉而,产生的衰落，或直射波因折射下凹而被地面的高地或高山阻挡,而发生的绕射性衰落。这种衰落的周期较长，约几分钟。,还是气候原因,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,波导型衰落,在无风的气候，在平原和水网地区，容易形成接近地面的波导层，使波束发生汇聚或发散而导致衰减性衰落。这种衰落的时间较长，有时可达几十分钟。,所以设计时就要考虑当地地形与气候,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,雨衰,在10GHZ频段以下，雨雾损耗并不显得特别严重，对一个中继段可能,会引入几个分贝。,在10GHZ以上频段，中继间隔主要受降雨损耗的限制，如对13GHZ以,上频段，100mm/小时的降雨会引起5dB/km的损耗，所以在13GHZ，,15GHZ频段，一般最大中继距离在10km左右。,在20GHZ以上频段，由于降雨损耗影响，中继间距只能有几公里。,越高频段雨衰越厉害！,高频段可以做用户级传输,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,衰落的一般特性,1、波长越短、距离越长，衰落越严重,2、夜间比白天严重，夏季比冬季严重,3、晴天，宁静天气比阴天、风雨天气时严重,4、水上电路比陆上电路严重,5、平地电路比山区电路严重,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,频率,用途,7,长距离干线,长距离干线,13G,中，短距离,中，短距离,中，短距离,中，短距离,短距离，城区,短距离，城区,短距离，城区,工作频段用途,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,对抗衰落措施,A.,不带分集,减小地面反射波电平,增大地面反射倾角,多种均衡措施,（时域均衡和频域均衡）,B.,分集技术,FD,频率分极.swf,SD,空间分极.swf,H,10.2/F,1/2,H 37/F,1/2,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,波导型,SD,FD,K,型,天线增益,天线高度,衰减型（阻挡，雨衰）降低频率,缩短站距,对抗衰落措施,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,2.微波通信系统方框图,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波通信系统方框图,信源,编码,TX BB,MOD,上变频,功放,分路系统,同步,RX,解码,RX BB,DEM,下变频,低噪放,分路系统,(调制),(解调),TX,Rx,天线,IF,UHF/SHF,BB:基带信号,BB,IF:中频,UHF:特高频(300-3000 MHz),SHF:超高频(3000 30,000 MHz),本振,发信：,发信设备组成.swf,收信：,收信设备组成.swf,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,微波电路方框图,MUX,环形器,终端站,终端站,中继站,MUX,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,数字微波常用调制技术,移相键控（,）,（,Phase Shift Keying,）,正交调幅（）,（,Quadature Amplitude Modulation）,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,2PSK 数字解调(BPSK),基带信号,载波信号,已调信号,已调信号,基带信号,载波信号,d1,d2,d3,d4,星座图,I,Q,环型调制器,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,4 PSK 调制器方框图,4PSK,S/P,H,OSC,/2,I,Q,星座图,I,Q,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,4 QAM 调制器方框图,4QAM,S/P,H,OSC,/2,AM,AM,I,Q,星座图,I,Q,提高频谱利用率,多状态调制（4,n,QAM）,尼奎斯特带宽=,Bite Rate,N,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,4 QAM,128 QAM,64 QAM,16 QAM,QAM 星座图,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,在选择数字微波中继通信系统的调制方式时，考虑的主要因素有频谱利用率、抗干扰能力、对传输失真的适应能力、抗衰落能力、勤务信号的传输方式、设备的复杂程度。,对于小容量系统（传输速率小于10Mb/s），以选择4PSK4DPSK为主，也可选择2PSK2DPSK或2FSK；,对于中容量系统（,传输速率大于10Mb/s且小于100Mb/s,）,，以选择4PSK4DPSK为主，也可选择8PSK或2PSK2DPSK；,对于大容量系统（,传输速率大于100Mb/s）,，可以选择16QAM为主，也可选择8PSK。,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,3.微波通信系统数字传输系列,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,准同步数字体系(PDH)(Plesiochronous,Digital Hierarchy),数字传输技术的应用是从市话中继传输开始的，为适应点对点的传输，PDH技术出现了。随着高速光纤通信系统在电信网中的应用，更多的电路被集中到少数的传输系统上，暴露出 PDH技术的不足：逐级复用造成上下电路复杂而不灵活；预留开销很小，不利于网络运行、管理和维护；北美制式和欧洲制式两大系列难以兼容互通；点对点传输基础上的复用结构缺乏灵活性，使传输设备利用率低，也不利于向同步网过渡等。,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,同步数字体系,(SDH)(Synchronous Digital Hierarchy),SDH采用同步时分交换技术，具有强大的网络运行、管理和维护功能，是高速大容量传输系统。与传统的PDH相比，其优点有：,(1)充分利用了光纤带宽宽的特性，将传输速率大大提高，目前已有10Gb/s速率的产品，可使传输容量明显提高。,(2)统一了北美制式和欧洲制式。,(3)使用标准的光接口，使得不同厂家的产品可以在光接口上实现互联，实现横向兼容。,(4)采用同步复用特性，只需利用软件即可使高速信号一次直接分插出低速支路信号。,(5)SDH的结构可使网络管理功能大大加强。,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,SDH 标准系列,PDH,SDH,日本,（T）,北美,（T）,欧洲,(E),6.312M,32.064,97.728,6.312,44.763,1.544,tel,fax,data,139.264,34.368,2.048M,8.448,STM-1 155.52 Mbps,ATM,PDH 网络,多媒体,3000s,交换,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,谢谢大家！,Evaluation only.,Created with Aspose.Slides for.NET 3.5 Client Profile 5.2.0.0.,Copyright 2004-2011 Aspose Pty Ltd.,