測繪英語unit15

1、Unit 15 The Global Positioning SystemUnit 15 The Global Positioning SystemUnit 15 The Global Positioning SystemNew words and ExpressionsDoppler： 多普勒效應(yīng)predecessor n.前輩；（被取代的）原有事物shift the scene： 換布景；換幕；改變環(huán)境implication n. 牽連；含意；推論，結(jié)論no longer： 不再，已不，已criterion kraitirin n. （批評判斷的）標(biāo)準(zhǔn)；準(zhǔn)則；規(guī)范；準(zhǔn)據(jù)field oper

2、ation： 野外操作not merely： 不只是，不單effective ifektiv adj. 有效的，起作用的；實(shí)際的，實(shí)在的；給人深刻印象cancellation knslein n. 取消；刪除with the result that： 因此；從而；其結(jié)果是part per million： 一百萬分之一Unit 15 The Global Positioning SystemNew words and Expressionscompete with： 與競爭essentially isenli adv. 本質(zhì)上；本來；基本上ephemeris n. 星歷表be referred

3、 to as： 被稱為monograph mnr:f, -rf n. 專題著作，專題論文progressively prgresivli adv. 漸進(jìn)地；日益增多地；逐漸的favorable feivrbl adj. 有利的；良好的；贊成的，贊許的；令人滿意的as it happens： 碰巧；偶然發(fā)生equally i:kwli adv. 同樣地；相等地，平等地；公平地mutual mju:tul, -tjul adj. 共同的；相互的，共有的regress rires vi. 逆行，倒退；復(fù)歸，復(fù)原；n. 回歸；退回as with： 正如；與一樣；就來說Unit 15 The Globa

4、l Positioning SystemNew words and Expressionsconsequently knsi,kwntli adv. 因此；結(jié)果；所以data acquisition： 數(shù)據(jù)采集，數(shù)據(jù)獲取geodetic datum： 大地基準(zhǔn)；測地基準(zhǔn)點(diǎn)contaminated kntmineitid adj. 受污染的；弄臟的；被污染的namely neimli adv. 也就是；即是；換句話說resection risekn n. 后方交會not nearly： 遠(yuǎn)非，相差很遠(yuǎn)，遠(yuǎn)不及impediment impedimnt n. 妨礙；阻止，阻礙vulnerable v

5、lnrbl adj. 易受攻擊的,易受的攻擊;易受傷害的;有弱點(diǎn)的differential mode： 差分式；差分法terminology n. 術(shù)語學(xué)；術(shù)語，專門名詞epoch n. 時代；歷元；（信號）出現(xiàn)時刻；恒定相位延遲Unit 15 The Global Positioning SystemNew words and Expressionsionospheric a. 電離層的pseudo-ranges：偽距（觀測）Integer cycle ambiguity:整周不定值，整周模糊度Standard positioning service: 標(biāo)準(zhǔn)定位服務(wù)Precise posit

6、ioning service:精確定位服務(wù)simultaneous a. 同時的；聯(lián)立的；同時發(fā)生的modulate v. 調(diào)節(jié)；（信號）調(diào)制； constellation n. 星座；星群oscillator n. 振蕩器quadrant n. 象限Unit 15 The Global Positioning SystemNew words and Expressionsencrypt v. 把編碼；把加密multipath effects： 多路徑效應(yīng)antenna n. 天線configuration n. 配置；立體基陣carrier phase： 載波相位ambiguous v. 模

7、糊不清的；引起歧義的；不明確；模棱兩可的transition signal： 中繼信號機(jī)；電子 過渡信號susceptible to： 易受.影響的；對敏感的Unit 15 The Global Positioning SystemNotes to the Text1.But GPS is not merely a replacement for TRANSIT. The simultaneous visibility of multiple satellites allows effective cancellation of the major sources of error in sa

8、tellite observations, with the result that with GPS, relative positioning accuracies of one part per million (ppm) or better over distances from one kilometer to thousands of kilometers are possible. This means that GPS can compete with terrestrial techniques over short distances, and can achieve mo

9、re accurate results in less time than TRANSIT observations over longer distances.譯文譯文:但GPS不只是代替中天儀。多個衛(wèi)星同時可視可以有效消除衛(wèi)星觀測中主要誤差源，因此，用GPS其相對定位精度從一公里到數(shù)百公里范圍內(nèi)有可能達(dá)到百萬分之一。這就意味著GPS在短距離上可以與地面測量技術(shù)相當(dāng)，在長距離上比中天儀用時更少，并能得到更高的精度。Unit 15 The Global Positioning SystemUnit 15 The Global Positioning System2.The satellite

10、signals consist of the L-band carrier waves modulated with a “Standard “or S code (formerly called the C/A code ), a “precise “ or P code and a Navigation Message containing, amongst other things, the coordinates of the satellites as functions of time-the “Broadcast Ephemerides . The S code which is

11、 intended mainly for civilian use , yields a range measurement precision of about 10 m , The navigation service provided by this code is referred to as the Standard Positioning Service (SPS), The P code is therefore referred to as the Precise Positioning Service (PPS). Although both codes can be use

12、d for surveying , a more accurate method is to measure the phase of the carrier signal. For this reason, we will not discuss the detailed characteristics of the codes in this monograph.Notes to the TextUnit 15 The Global Positioning System譯文譯文:衛(wèi)星信號由調(diào)制的L-波段載波組成，它是用一個“標(biāo)準(zhǔn)的”或稱S的電碼(以前稱為C/A碼，一個“精確的”或稱P的電碼

13、以一個導(dǎo)航信息調(diào)制的，衛(wèi)星的坐標(biāo)作為時間“廣播星歷”的函數(shù)。S碼主要是為民用，它可得到大約10m的距離測量精度，由這個碼提供的導(dǎo)航服務(wù)為標(biāo)準(zhǔn)定位服務(wù)(SPS)，因此P碼就是精確定位服務(wù)(PPS)。雖然兩個碼都用于測量，但更精確的方法是測量載波信號的相位。因此，在本文中我們將不詳細(xì)討論碼的特點(diǎn)。Notes to the TextUnit 15 The Global Positioning System3.All satellite positioning systems provide ground coordinates of a receiver (or the baseline vecto

14、r between a pair of receives) in an earth-centered coordinate system. The orientation of the system is determined by the tabulated coordinates or ephemerides of the GPS satellites. In order to relate coordinates determined by GPS surveying to the local geodetic datum a transformation relationship ne

15、eds to be established. 譯文譯文:所有衛(wèi)星定位系統(tǒng)都提供接收機(jī)的地心坐標(biāo)系的坐標(biāo)(或兩個接收機(jī)之間的基線矢量。系統(tǒng)的定向由坐標(biāo)表或GPS衛(wèi)星的星歷確定。為了將GPS測量確定的坐標(biāo)與地方大地基準(zhǔn)聯(lián)系起來，需要建立起轉(zhuǎn)換關(guān)系。Notes to the TextUnit 15 The Global Positioning SystemNotes to the Text4.When four satellites are observed simultaneously, it is possible to determine the three-dimensional posit

16、ion of the ground receiver, and the receiver clock offset, at a single epoch. This is simply resection by distance, in surveying terminology, with the technique the precision is a function of the geometry of the receiver in relation to the four visible satellites. The best geometry would be when the satellites are in each of the four quadrants and each at an elevation angle of 4070 above the horizon. However, pseudo-range measurements are not nearly as precise as phase measurements of the