机载监视系统课件：2-0机载气象雷达 - 雷达基本原理20160329.ppt

1、Airborne Weather Radar(WXR)Airborne Weather Radar(WXR)中国民航大学中国民航大学电子信息与自动化学院电子信息与自动化学院电子信息与自动化学院Airborne Weather RadarContentsContentsCon1Con1：Radar principleRadar principleCon2: Introduction to WXRCon2: Introduction to WXRCon3Con3：Ranging,Azimuth measurement,MTIRanging,Azimuth measurement,MTICon4Co

2、n4：Transmitter,ReceiverTransmitter,ReceiverCon5Con5：Antenna,CP,DisplayAntenna,CP,Display2Airborne Weather Radar(WXR)Airborne Weather Radar(WXR) Con1 Con1：Radar principleRadar principle电子信息与自动化学院Airborne Weather RadarOutlines For Con10 0 雷达历史雷达历史1 1 雷达的定义和类型雷达的定义和类型2 2 雷达探测目标的原理雷达探测目标的原理3 3 雷达基本组成雷达基

3、本组成4 4 雷达方程雷达方程4电子信息与自动化学院Airborne Weather RadarCon1-0 Con1-0 雷达历史雷达历史 Why we need radarWhy we need radar？v ATC functionATC functionProvision of safe and expeditious sequencing of traffic;Provision of safe and expeditious sequencing of traffic;Provision of safe horizontal and vertical separation;Pro

4、vision of safe horizontal and vertical separation;Safe meaning: No collisionSafe meaning: No collision5电子信息与自动化学院Airborne Weather RadarSeparation minimaSeparation minima6电子信息与自动化学院Airborne Weather RadarFormer controllerFormer controller7电子信息与自动化学院Airborne Weather RadarCurrent controllerCurrent contr

5、oller8电子信息与自动化学院Airborne Weather RadarPPI: Plan Position IndicatorPPI: Plan Position Indicator9电子信息与自动化学院Airborne Weather Radar10PPI and cluttersPPI and clutters电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型RADAR: RADAR: RARAdio dio D Detection etection A And nd R Ranginganging雷达：无线电

6、探测与测距雷达：无线电探测与测距One of the most important surveillance One of the most important surveillance sensorssensors11电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型12PSR: Primary Surveillance RadarSSR: Secondary Surveillance Radar电子信息与自动化学院Airborne Weather Radar雷达频段WXR: 93009375Mhz13Con1-1 C

7、on1-1 雷达的定义和类型雷达的定义和类型电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型14电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型15电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型 Radar is an Radar is an electromagneticelectromagnetic（EMEM） system system for the for

8、the detection and location of reflecting objects such detection and location of reflecting objects such as aircraft, ships, spacecraft, vehicles, people as aircraft, ships, spacecraft, vehicles, people and the natural environment.and the natural environment. Radar can perform its function at long or

9、 short Radar can perform its function at long or short distances and it can operate in darkness, haze, distances and it can operate in darkness, haze, fog, rain, and snow. Its ability to measure fog, rain, and snow. Its ability to measure distance with distance with high accuracyhigh accuracy and in

10、 and in all weather all weather is is one of its most important attributes.one of its most important attributes. The range of radars can exceed The range of radars can exceed hundreds of miles hundreds of miles and they can be placed on mobile platforms greatly and they can be placed on mobile platf

11、orms greatly increasing their effectivity.increasing their effectivity.16电子信息与自动化学院Airborne Weather RadarCon1-1 Con1-1 雷达的定义和类型雷达的定义和类型v 按雷达接收回波方式按雷达接收回波方式 一次雷达（一次雷达（PSRPSR，Primary Surveillance Radar）：发射一束射频）：发射一束射频能量，接收由目标反射回来的一小部分能量，接收由目标反射回来的一小部分能量，主要用于进近和场面。能量，主要用于进近和场面。(Non-(Non-cooperative, 2D

12、 position)cooperative, 2D position) 二次雷达（二次雷达（SSRSSR，Secondary Surveillance Radar）：发射一组飞机）：发射一组飞机应答机可以识别的特征脉冲，由飞机在应答机可以识别的特征脉冲，由飞机在约定时间间隔内发射一串应答编码脉冲，约定时间间隔内发射一串应答编码脉冲，主要用于航路。主要用于航路。(Cooperative,3D (Cooperative,3D position)position)17电子信息与自动化学院Airborne Weather Radarv The simplest radar system transmi

13、ts a pulse of The simplest radar system transmits a pulse of high frequency energy and listens for the echo high frequency energy and listens for the echo of that pulse.of that pulse.v Given that EM energy travels at , the Given that EM energy travels at , the time it takes for a pulse to travel to

14、a target time it takes for a pulse to travel to a target and the echo to travel back will tell us the and the echo to travel back will tell us the range.range.R = cTR = cTR R/2/2where R = range in meterswhere R = range in metersc = the speed of the EM pulsec = the speed of the EM pulseT TR R = the r

15、ound trip transit time = the round trip transit timesm/103818Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airborne Weather RadarCon1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理v The radar dish or antenna transmits pulses of radio waves or microwaves which bounce off any object in their path. v The object returns a tin

16、y part of the waves energy to the radar dish or antenna which is usually located at the same site as the transmitter.v Obviously, we cannot send out another pulse until a time window has passed, in which we expect to see a return echo.19电子信息与自动化学院Airborne Weather RadarCon1-2 Con1-2 雷达探测目标的原理雷达探测目标的原

17、理20电子信息与自动化学院Airborne Weather Radar 目标斜距的测量目标斜距的测量(测距测距)2R=ctr 2rctR 式中式中, R为目标到雷达站的单程距离为目标到雷达站的单程距离, 单位为单位为m; tr为电磁波往返于为电磁波往返于目标与雷达之间的时间间隔目标与雷达之间的时间间隔, 单位为单位为s; c为光速，为光速，c=3108m/s。计算计算1us，1ms雷达探测距离，探测雷达探测距离，探测100NM所需时间。所需时间。Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理21电子信息与自动化学院Airborne Weather Radar发射脉冲回波噪声t

18、rtrtt 目标斜距的测量（目标斜距的测量（测距测距）Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理22电子信息与自动化学院Airborne Weather Radar23Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airborne Weather Radar目标O 目标角度的测量（目标角度的测量（测角测角）雷达天线波束扫描原理Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理24条件条件: （1）电磁波沿直线传播）电磁波沿直线传播 （2）雷达天线具有方向性）雷达天线具有方向性电子信息与自动化学院Airborne Weat

19、her Radar天线方向性天线方向性 天线的方向性可用它的方向性函数或根据方向性函数画出天线的方向性可用它的方向性函数或根据方向性函数画出的方向图表示。的方向图表示。(方位角，俯仰角方位角，俯仰角)max( , )( , )( , )EfE Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airborne Weather Radar26Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airborne Weather Radar27Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airb

20、orne Weather Radar28Con1-2 Con1-2 雷达探测目标的原理雷达探测目标的原理电子信息与自动化学院Airborne Weather RadarCon1-3 Con1-3 雷达基本组成雷达基本组成29电子信息与自动化学院Airborne Weather Radar30Con1-3 Con1-3 雷达基本组成雷达基本组成电子信息与自动化学院Airborne Weather Radar31Con1-3 Con1-3 雷达基本组成雷达基本组成电子信息与自动化学院Airborne Weather Radar32Con1-3 Con1-3 雷达基本组成雷达基本组成电子信息与自动化

21、学院Airborne Weather Radar33Con1-3 Con1-3 雷达基本组成雷达基本组成电子信息与自动化学院Airborne Weather RadarCon1-4 Con1-4 雷达方程雷达方程假设：1，天线各向同性且均匀辐射（spherical spreading）2，接收发射采用同一部天线P 发射机功率G 天线增益R 探测距离 目标截面积34电子信息与自动化学院Airborne Weather RadarCon1-4 Con1-4 雷达方程雷达方程Ae天线有效接收面积Smin最小检测信号功率35电子信息与自动化学院Airborne Weather RadarCon1-4

22、Con1-4 雷达方程雷达方程36电子信息与自动化学院Airborne Weather RadarCon1-4 Con1-4 雷达方程雷达方程41min322max41min22max)4(4itirtSGPRSAPR22224344(4 )trtrPAPGPRR Pr：雷达接收功率：雷达接收功率Pt：雷达发射功率：雷达发射功率G：雷达天线的增益：雷达天线的增益：目标的散射截面积：目标的散射截面积Ar = Ae ：接收天线的有效接收面积：接收天线的有效接收面积：所用波长：所用波长24eAAG 42AeGA 37电子信息与自动化学院Airborne Weather Radar38Con1-4 C

23、on1-4 雷达方程雷达方程电子信息与自动化学院Airborne Weather Radar39Con1-4 Con1-4 雷达方程雷达方程-RCS-RCSRCS是一假想面积，是描述目标在一定入射功率下后向散射功率能力的量，该量以面积单位来描述。面积越大，后向散射能力越强，产生的回波功率也就越大。电子信息与自动化学院Airborne Weather Radar40Con1-4 Con1-4 雷达方程雷达方程-RCS-RCS电子信息与自动化学院Airborne Weather RadarCon1-4 Con1-4 雷达方程雷达方程-RCS-RCS41海鸥的形体与燕八哥相近，但海鸥的雷达反射截面却

24、比燕八哥大200倍。蜜蜂的体积小于麻雀，但它的雷达反射截面反而比麻雀大16倍。可见，体积的大小并不是决定隐蔽能力的唯一因素，体形才是决定隐身的关键。普通飞机无论何种姿态，都可以产生雷达回波，隐形飞机的则会长时间无回波，偶尔产生强烈回波（即亮点）电子信息与自动化学院Airborne Weather RadarQuestions ?Questions ?421 What is radar?2 How does it work?3 What is it used for in ATC system?4 Which university and which specialty?5 When and where radar was born?6 Who set up radar network along its coast?