1、MARINE RADAR AND ARPAChapter 1 Basic Principle of RadarMarine Radar and ARPAChapter 1Basic Principle of RadarThe Development&Principle of Marine Radar Radar ConceptThe development of radar techniqueThe use of radar at sea General DescriptionThe principle of range and bearing measurement Display pres
2、entation of a basic radarMarine Radar and ARPAChapter 1Basic Principle of RadarRadar ConceptGeneral Concept RadarRadio detection and rangingFrom 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 wh
3、ich can be used to find the targets and to measure or determinate the targets information/data by way of the characteristics of electromagnetic wave.Marine Radar and ARPAChapter 1Basic Principle of RadarThe characteristic of electromagnetic wave:ReflactionFind:ReflectRelayRadiateTargets:All the obje
4、cts that can be found by radar.Targets information/data:position speed,course,collision avoidance informationconstant speedstraight lineMarine Radar and ARPAChapter 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、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
5、围。称为标、速度及避碰参数的一个无线电技术范围。称为“雷雷达达”。“二次辐射二次辐射”：雷达发射电磁波到目标后、目标产生：雷达发射电磁波到目标后、目标产生“二二次辐射次辐射”，其中一小部分被雷达天线接收，称为目标回，其中一小部分被雷达天线接收，称为目标回波波,雷达收到回波便可发现目标。雷达收到回波便可发现目标。“转发转发”：来自应答器（来自应答器（Transponder），），“识别器识别器”，后者收到雷达信号后发射经过编码的后者收到雷达信号后发射经过编码的“应答波应答波”被雷达被雷达所接收，从而发现目标。所接收，从而发现目标。“固有辐射固有辐射”：来自具有固有辐射源的目标（如飞机、：来自具有
6、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标的固有辐射波而发现目标。Marine Radar and ARPAChapter 1Basic Principle of Radar现代雷达与电子计算机、图象处理、数据处理、自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、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。显示、控制和管理。Marine Radar
7、 and ARPAChapter 1Basic Principle of Radar1886-1888 Hertz(Germany):realized electromagnetic wave oscillating,transmitting,receiving.1914(American):Echo sounderProto-model of radar.1922 Marconi(Italy):Suggested a practicable radar system.1930 Blair:Pulse echo measurement(range,direction)systembasic r
8、adar.Marine Radar and ARPAChapter 1Basic Principle of RadarRCA 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 na
9、vigation system(Loran,GPS,ECDIS,AIS),colour TV display Automatic bridge navigation system.Marine Radar and ARPAChapter 1Basic Principle of RadarRadar/ARPA,ECDIS,GPS/DGPS and data auto-pilot combined together will be future major navigation systemMarine Radar and ARPAChapter 1Basic Principle of Radar
10、雷达发展历程雷达发展历程模拟信号处理模拟信号处理数字信息处理数字信息处理计算机信息处理计算机信息处理Marine Radar and ARPAChapter 1Basic Principle of Radar模拟信号处理模拟信号处理20世纪世纪90年代前，雷达设备采用电子管或晶体管，发年代前，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，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优
11、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，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，因而被称为驾驶员像稳定清晰，操作简单方便，因而被称为驾驶员“眼眼睛睛”缺点：采用实时的模拟信号处理系统和径向圆周扫描缺点：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，无法实现彩色显示实现彩色显示Marine Radar and ARPAChapter 1Basic Principle of RadarMarine Radar and ARPAChapt
12、er 1Basic Principle of Radar数字信号处理数字信号处理雷达设备进步雷达设备进步采用数字处理技术采用数字处理技术采用高亮度光栅扫描显示（采用高亮度光栅扫描显示（TV显示）显示）实现实现ATT和和ARPA功能功能Marine Radar and ARPAChapter 1Basic Principle of Radar计算机信息处理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，雷达功能更加强大星定位技术的发展，雷达功能更加强大Marine Radar and ARPAChapter 1Basic
13、 Principle of RadarThe use of radar at sea Marine radar:Centi-metric wavelength pulse transmitting navigational radarFor our major:The use of radar at sea.Three main applications:fixposition(2)collision anti-(1).course velocity,bearing),direction(distance,targetsof parameters theMeasure visibilityof
14、limitation of free(2)detection range long(1)possible asearly as targetsFind(3)Navigating the ship Marine Radar and ARPAGeneral DescriptionScan directionRange:Echo(at 10 nm)t123.5ss Periphery of CRTOwn shipTargetIsland12 nmTarget90 245 245EBL901802700Bearing markerChart formRadar pictureFig.Range&bea
15、ring measurementSweep line(Length 148.2s Equivalent 12 nm range)Ring(6 Total)HLIslandOwn shipRadar cannot“feel”the back side of a target,therefor target distortion is inevitable.Chapter 1Basic Principle of RadarMarine Radar and ARPAChapter 1Basic Principle of Radar雷达图像特点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雷
16、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、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；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：大的变形，表现在：P6Marine Radar and ARPAChapter 1Basic Principle of Radar1.Range measurement t:during which radio wave to and form the target,C:electromagne
17、tic wave travel velocity in free space.R=slant range(antenna aim)Marine Radar and ARPAChapter 1Basic Principle of Radart: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
18、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.Marine Radar and ARPAChapter 1Basic Principle of RadarAn echo
19、 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.Marine Radar and ARPAChapter 1Basic Pr
20、inciple of RadarBearing measurement By way of directional antenna(Scanner,Aerial).Marine Radar and ARPAChapter 1Basic Principle of RadarMarine Radar and ARPAChapter 1Basic Principle of RadarBearing measurement By way of directional antenna(Scanner,Aerial).Marine Radar and ARPAChapter 1Basic Principl
21、e of RadarMarine Radar and ARPAMarine Radar and ARPA1.2.2 The echo principleThe 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.
