第一章 航海雷達基本原理

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 pr

2、esentation 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 syst

3、em 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.Marine Radar and ARPAChapter 1Basic Principle of RadarThe characteristic of electromagnetic wave: ReflactionFind: ReflectRelayRadiateTargets: All

4、the objects that can be found by radar. Targets information/data: position speed, course, collision avoidance informationconstant speedstraight lineMarine Radar and ARPAChapter 1Basic Principle of Radar雷達是一種主動遙感設備，它利用電磁波的二次輻射雷達是一種主動遙感設備，它利用電磁波的二次輻射、轉發(fā)或固有輻射來探測目標，并測定目標的空間坐、轉發(fā)或固有輻射來探測目標，并測定目標的空間坐標、速度及避

5、碰參數的一個無線電技術范圍。稱為標、速度及避碰參數的一個無線電技術范圍。稱為“雷雷達達”?！岸屋椛涠屋椛洹保豪走_發(fā)射電磁波到目標后、目標產生：雷達發(fā)射電磁波到目標后、目標產生“二二次輻射次輻射”，其中一小部分被雷達天線接收，稱為目標回，其中一小部分被雷達天線接收，稱為目標回波波, 雷達收到回波便可發(fā)現目標。雷達收到回波便可發(fā)現目標。“轉發(fā)轉發(fā)”： 來自應答器（來自應答器（Transponder），），“識別器識別器”，后者收到雷達信號后發(fā)射經過編碼的后者收到雷達信號后發(fā)射經過編碼的“應答波應答波”被雷達被雷達所接收，從而發(fā)現目標。所接收，從而發(fā)現目標。“固有輻射固有輻射”：來自具有固有輻射

6、源的目標（如飛機、：來自具有固有輻射源的目標（如飛機、發(fā)動機、核爆炸、目標上無線電裝置等）雷達接收目發(fā)動機、核爆炸、目標上無線電裝置等）雷達接收目標的固有輻射波而發(fā)現目標標的固有輻射波而發(fā)現目標。Marine Radar and ARPAChapter 1Basic Principle of Radar現代雷達與電子計算機、圖象處理、數據處理、自現代雷達與電子計算機、圖象處理、數據處理、自動控制等技術結合，又具有自動信息處理功能及智動控制等技術結合，又具有自動信息處理功能及智能化顯示終端，可自動、迅速、準確地完成測量、能化顯示終端，可自動、迅速、準確地完成測量、顯示、控制和管理。顯示、控制和管

7、理。Marine Radar 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 (ra

8、nge, direction) systembasic radar. 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. Moder

9、n radar/ARPA: With computer, integrated navigation 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

10、 Radar and ARPAChapter 1Basic Principle of Radar雷達發(fā)展歷程雷達發(fā)展歷程模擬信號處理模擬信號處理數字信息處理數字信息處理計算機信息處理計算機信息處理Marine Radar and ARPAChapter 1Basic Principle of Radar模擬信號處理模擬信號處理20世紀世紀90年代前，雷達設備采用電子管或晶體管，發(fā)年代前，雷達設備采用電子管或晶體管，發(fā)射功率較大，回波信號經接收系統(tǒng)實時處理，直接顯射功率較大，回波信號經接收系統(tǒng)實時處理，直接顯示在徑向圓周掃描顯示器（平面位置顯示器，示在徑向圓周掃描顯示器（平面位置顯示器，Plan

11、 Position Indicator - PPI）優(yōu)點：技術成熟，具有良好的探測的分辨目標的能力優(yōu)點：技術成熟，具有良好的探測的分辨目標的能力，接收信噪比高，抗干擾能力強，故障率低，目標圖，接收信噪比高，抗干擾能力強，故障率低，目標圖像穩(wěn)定清晰，操作簡單方便，因而被稱為駕駛員像穩(wěn)定清晰，操作簡單方便，因而被稱為駕駛員“眼眼睛睛”缺點：采用實時的模擬信號處理系統(tǒng)和徑向圓周掃描缺點：采用實時的模擬信號處理系統(tǒng)和徑向圓周掃描顯示器，熒光屏的顯示亮度和對比度受到限制，無法顯示器，熒光屏的顯示亮度和對比度受到限制，無法實現彩色顯示實現彩色顯示Marine Radar and ARPAChapter 1

12、Basic Principle of RadarMarine Radar and ARPAChapter 1Basic Principle of Radar數字信號處理數字信號處理雷達設備進步雷達設備進步采用數字處理技術采用數字處理技術采用高亮度光柵掃描顯示（采用高亮度光柵掃描顯示（TV顯示）顯示）實現實現ATT和和ARPA功能功能Marine Radar and ARPAChapter 1Basic Principle of Radar計算機信息處理計算機信息處理隨著傳感網技術、現代通信技術、信息處理技術和衛(wèi)隨著傳感網技術、現代通信技術、信息處理技術和衛(wèi)星定位技術的發(fā)展，雷達功能更加強大星定

13、位技術的發(fā)展，雷達功能更加強大Marine Radar and ARPAChapter 1Basic 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),directi

14、on( distance, targetsof parameters theMeasure visibilityoflimitation 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 24

15、5EBL901802700Bearing markerChart formRadar pictureFig. Range & bearing 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 A

16、RPAChapter 1Basic Principle of Radar雷達圖像特點雷達圖像特點雷達圖像不同于海圖，也不同于日常生活中的視覺雷達圖像不同于海圖，也不同于日常生活中的視覺圖像；雷達圖像與設備自身性能、大氣船舶條件、圖像；雷達圖像與設備自身性能、大氣船舶條件、目標反射特性以及周圍環(huán)境變化有關；目標反射特性以及周圍環(huán)境變化有關；雷達探測到的回波圖像與真實目標相比，可能有較雷達探測到的回波圖像與真實目標相比，可能有較大的變形，表現在：大的變形，表現在：P6Marine Radar and ARPAChapter 1Basic Principle of Radar1. Range mea

17、surement t: during which radio wave to and form the target, C: electromagnetic 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 v

18、ery 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 targ

19、et at a chosen range.Marine Radar and ARPAChapter 1Basic Principle of RadarAn 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. Marine Radar and ARPAChapter 1Basic Principle of RadarBearing measurement By way of directional antenna (Scanner , Aeria