第一章航海雷达基本原理课件

,单击此处编辑母版文本样式,第二级,第三级,第四级,第五级,#,Marine Radar,and ARPA,MARINE RADAR AND ARPA,MARINE RADAR AND ARPA,1,Chapter 1 Basic Principle of,Radar,Chapter 1 Basic Principle of,2,Chapter 1Basic Principle of Radar,The Development & Principle of Marine Radar,Radar Concept,The,development of radar technique,The,use of radar at sea,General,Description,The,principle of range and bearing measurement,Display presentation,of a basic radar,Chapter 1Basic Principle of,3,Chapter 1Basic Principle of Radar,Radar Concept,General Concept,Radar,Ra,dio,d,etection,a,nd,r,anging,From the name: To find and measure the targets that you concern about by way of radio magnetic wave.,Scientific definition: Radar is a kind of electronic system which can be used to,find,the,targets,and to measure or determinate the targets,information/data,by way of,the characteristics of electromagnetic wave,.,Chapter 1Basic Principle of,4,Chapter 1Basic Principle of Radar,The,characteristic of electromagnetic wave:,Reflaction,Find:,ReflectRelayRadiate,Targets,:,All the objects that can be found by radar.,Targets,information/data:,position speed, course,collision avoidance information,constant speed,straight line,Chapter 1Basic Principle of,5,Chapter 1Basic Principle of Radar,雷达是一种主动遥感设备，它利用电磁波的二次辐射、转发或固有辐射来探测目标，并测定目标的空间坐标、速度及避碰参数的一个无线电技术范围。称为“雷达”。,“二次辐射”：雷达发射电磁波到目标后、目标产生“二次辐射”，其中一小部分被雷达天线接收，称为目标回波,雷达收到回波便可发现目标。,“转发”： 来自应答器（,Transponder,），“识别器”，后者收到雷达信号后发射经过编码的“应答波”被雷达所接收，从而发现目标。,“固有辐射”：来自具有固有辐射源的目标（如飞机、发动机、核爆炸、目标上无线电装置等）雷达接收目标的固有辐射波而发现目标,。,Chapter 1Basic Principle of,6,Chapter 1Basic Principle of Radar,现代雷达与电子计算机、图象处理、数据处理、自动控制等技术结合，又具有自动信息处理功能及智能化显示终端，可自动、迅速、准确地完成测量、显示、控制和管理。,Chapter 1Basic Principle of,7,Chapter 1Basic Principle of Radar,1886-1888 Hertz (Germany): realized electromagnetic wave,oscillating, transmitting, receiving.,1914 (American): Echo sounder,Proto-model of radar.,1922 Marconi (Italy): Suggested a practicable radar system.,1930 Blair: Pulse echo measurement (range, direction) system,basic radar.,Chapter 1Basic Principle of,8,Chapter 1Basic Principle of Radar,RCA Co. (American): Invented airplane-carried radar.,(America): “New York” Cruiser equipped with radar.,After WWII: As a navigation aids developed rapidly.,China: Technique mainly from developed countries.,Modern radar/ARPA: With computer, integrated navigation system (Loran, GPS, ECDIS,AIS), colour TV display Automatic bridge navigation system.,Chapter 1Basic Principle of,9,Chapter 1Basic Principle of Radar,Radar/ARPA, ECDIS, GPS/DGPS and data auto-pilot combined together will be future major navigation system,Chapter 1Basic Principle of,10,Chapter 1Basic Principle of Radar,雷达发展历程,模拟信号处理,数字信息处理,计算机信息处理,Chapter 1Basic Principle of,11,Chapter 1Basic Principle of Radar,模拟信号处理,20,世纪,90,年代前，雷达设备采用电子管或晶体管，发射功率较大，回波信号经接收系统实时处理，直接显示在径向圆周扫描显示器（平面位置显示器，,Plan Position Indicator - PPI,）,优点：技术成熟，具有良好的探测的分辨目标的能力，接收信噪比高，抗干扰能力强，故障率低，目标图像稳定清晰，操作简单方便，因而被称为驾驶员“眼睛”,缺点：采用实时的模拟信号处理系统和径向圆周扫描显示器，荧光屏的显示亮度和对比度受到限制，无法实现彩色显示,Chapter 1Basic Principle of,12,Chapter 1Basic Principle of Radar,Chapter 1Basic Principle of,13,Chapter 1Basic Principle of Radar,数字信号处理,雷达设备进步,采用数字处理技术,采用高亮度光栅扫描显示（,TV,显示）,实现,ATT,和,ARPA,功能,Chapter 1Basic Principle of,14,Chapter 1Basic Principle of Radar,计算机信息处理,随着传感网技术、现代通信技术、信息处理技术和卫星定位技术的发展，雷达功能更加强大,Chapter 1Basic Principle of,15,Chapter 1Basic Principle of Radar,The use of radar at sea,Marine radar: Centi-metric wavelength pulse,transmitting navigational radar,For our major: The use of radar at sea.,Three main applications:,fix,position,(2),collision,anti-,(1),.,course,velocity,bearing),direction(,distance,targets,of,parameters,the,Measure,visibility,of,limitation,of,free,(2),detection,range,long,(1),possible,as,early,as,targets,Find,(3),Navigating the ship,Chapter 1Basic Principle of,16,General Description,Scan direction,Range:,Echo (at 10 nm),t,123.5,s,Periphery of CRT,Own,ship,Target,Island,12 nm,Target,90,245,245,EBL,90,180,270,0,Bearing marker,Chart,form,Radar,picture,Fig. Range & bearing,measurement,Sweep line (Length 148.2,s,Equivalent 12 nm range),Ring (6 Total),HL,Island,Own,ship,Radar cannot “feel” the back side of a target, therefor target distortion is inevitable.,Chapter 1Basic Principle of Radar,General DescriptionScan direct,17,Chapter 1Basic Principle of Radar,雷达图像特点,雷达图像不同于海图，也不同于日常生活中的视觉图像；雷达图像与设备自身性能、大气船舶条件、目标反射特性以及周围环境变化有关；,雷达探测到的回波图像与真实目标相比，可能有较大的变形，表现在：,P6,Chapter 1Basic Principle of,18,Chapter 1Basic Principle,of Radar,1. Range measurement,t,: during which radio wave to and form the target,C,: electromagnetic wave travel velocity in free space.,R = slant range (antenna aim),Chapter 1Basic Principle of,19,Chapter 1Basic Principle of Radar,t: very shot;beyond the capability of,any,conventional time measuring,device; Electronic,deviceCRT.,A very small spot of light.,The,speed of this travel can be accurately controlled at,values,which allow the spot to transit the screen in as little,as,a few microseconds.,The time taken for the spot to cross the,screen,is the same,as,the time taken for a radar pulse to make the two-way,journey,to a target at a chosen range.,Chapter 1Basic Principle of,20,Chapter 1Basic Principle of Radar,An echo return from a target is used to,produce,an increase in the brilliance of,the,moving spot.,When the spot has completed the,trace, the brilliance is automatically reduced to zero and the spot flies back to the origin to await the incidence of the next transmission.,Chapter 1Basic Principle of,21,Chapter 1Basic Principle of Radar,Bearing measurement,By,way of directional,antenna (Scanner , Aerial).,Chapter 1Basic Principle of,22,Chapter 1Basic Principle of Radar,Chapter 1Basic Principle of,23,Chapter 1Basic Principle of Radar,Bearing measurement,By,way of directional antenna (Scanner , Aerial),.,Chapter 1Basic Principle of,24,Chapter 1Basic Principle of Radar,Chapter 1Basic Principle of,25,第一章航海雷达基本原理课件,26,1.2.2,The echo principle,The echo is never as loud as the original blast.,The chance of detecting an echo depends on the loudness and duration of the original blast.,Short blasts are required if echoes from close targets are not to be drowned by the original blast.,A sufficiently long interval between blasts is required to allow time for echoes from distant targets to return.,1.2.2 The echo principleThe ec,27,