【正文】
美國(guó)己經(jīng)廣域增強(qiáng)系統(tǒng)WAAS (即將廣域差分系統(tǒng)中的發(fā)送修正數(shù)據(jù)鏈轉(zhuǎn)為地球同步衛(wèi)星發(fā)送,使地球同步衛(wèi)星也具有C/A碼功能,形成廣域GPS增強(qiáng)系統(tǒng))計(jì)劃發(fā)展成國(guó)際標(biāo)準(zhǔn)。許多商業(yè)和政府機(jī)構(gòu)也使用GPS 設(shè)備來(lái)跟蹤他們的車輛位置,這一般需要借助無(wú)線通信技術(shù)。(3)放樣放樣是測(cè)量的一個(gè)應(yīng)用分支,它要求通過(guò)一定方法,采用一定儀器把人為設(shè)計(jì)好的地位在實(shí)地給標(biāo)定出來(lái),過(guò)去采用常規(guī)的測(cè)量放樣方法很多,如:經(jīng)緯儀交會(huì)放樣,全站儀的邊角放樣等等,一般要放樣出一個(gè)設(shè)計(jì)點(diǎn)位時(shí),往往需要來(lái)回移動(dòng)目標(biāo),而且要23人操作,同時(shí)在放樣過(guò)程中還要求點(diǎn)與點(diǎn)間通視情況良好,在生產(chǎn)應(yīng)用上效率不是很高,有時(shí)放樣中遇到困難的情況很復(fù)雜,要借助于很多方法才能放樣,如果采用RTK技術(shù)放樣時(shí),僅需把設(shè)計(jì)好的點(diǎn)位坐標(biāo)輸入到電子手薄中,背著GPS 接收機(jī),它會(huì)提醒你走到要放樣點(diǎn)的位置,即迅速又方便,由于GPS是通過(guò)坐標(biāo)來(lái)直接放樣的,而且精度很高也很均勻,因而在外業(yè)放樣中效率會(huì)大大提高,且只需一人操作。流動(dòng)站不僅通過(guò)數(shù)據(jù)鏈接收來(lái)自基準(zhǔn)站的數(shù)據(jù),還要采集GPS 觀測(cè)數(shù)據(jù),并在系統(tǒng)內(nèi)組成差分觀測(cè)值進(jìn)行實(shí)時(shí)處理,同時(shí)給出厘米級(jí)定位結(jié)果,歷時(shí)不到一秒鐘。相對(duì)定位(差分定位)是根據(jù)兩臺(tái)以上接收機(jī)的觀測(cè)數(shù)據(jù)來(lái)確定觀測(cè)點(diǎn)之間的相對(duì)位置的方法,它既可采用偽距觀測(cè)量也可采用相位觀測(cè)量,大地測(cè)量或工程測(cè)量均應(yīng)采用相位觀測(cè)值進(jìn)行相對(duì)定位。GPS接收機(jī)對(duì)碼的量測(cè)就可得到衛(wèi)星到接收機(jī)的距離,由于含有接收機(jī)衛(wèi)星鐘的誤差及大氣傳播誤差,故稱為偽距。雖然GPS系統(tǒng)一開(kāi)始是為軍事目的而建立的,但很快在民用方面得到了極大的發(fā)展,各類GPS 接收機(jī)和處理軟件紛紛涌現(xiàn)出來(lái)。GPS是以衛(wèi)星定位和時(shí)間傳輸為基礎(chǔ),GPS定位功能在現(xiàn)代測(cè)量和現(xiàn)代建設(shè)中有較為廣泛的應(yīng)用,GPSRTK技術(shù)也在現(xiàn)代化建設(shè)中有著廣泛的應(yīng)用,現(xiàn)在GPS 也已經(jīng)顯示出對(duì)平民社區(qū)的一種重要的利益,且其應(yīng)用范圍越來(lái)越廣泛。 will use in to forecast the future for several months the satellite to locate the summary position forecast star experience。 Uses in calculates when the localization to need the satelli te coordinates the broadcast star experience, the precision is (each satellite is different several meter to several dozens meters~changes as necessary)。關(guān)鍵詞:GPS、定位、RTK、放樣、測(cè)量背景五十年代末,原蘇聯(lián)發(fā)射了人類的第一顆人造地球衛(wèi)星,美國(guó)科學(xué)家在對(duì)其的跟蹤研究中,發(fā)現(xiàn)了多普勒頻移現(xiàn)象,并利用該原理促成了多普勒衛(wèi)星定位導(dǎo)航系統(tǒng)的建成,在軍事和民用方面取得了巨大的成功,是導(dǎo)航定位史上的一次飛躍,我國(guó)也曾引進(jìn)了多臺(tái)多普勒接收機(jī),應(yīng)用與海島聯(lián)測(cè)、地球勘探等領(lǐng)域。能對(duì)兩個(gè)頻率進(jìn)行觀測(cè)的接收機(jī)稱為雙頻接收機(jī),只能對(duì)一個(gè)頻率進(jìn)行觀測(cè)的接收機(jī)稱為單頻接收機(jī),他們?cè)诰群蛢r(jià)格上均有較大區(qū)別。對(duì)OA碼測(cè)得的偽距稱為UA碼偽距,精度約為20米左右,對(duì)P碼測(cè)得的偽距稱為P碼偽距,精度約為2 米左右。在GPS觀測(cè)量中包含了衛(wèi)星和接收機(jī)的鐘差、大氣傳播延遲、多路經(jīng)效應(yīng)等誤差,在定位計(jì)算時(shí)還要受到衛(wèi)星廣播星歷誤差的影響,在進(jìn)行相對(duì)定位時(shí)大部分公共誤差被抵消或削弱,因此定位精度降大大提高,雙頻接收機(jī)可以根據(jù)兩個(gè)頻率的觀測(cè)量抵消大氣中電離層誤差的主要部分,在精度要求高,接收機(jī)間距離較遠(yuǎn)時(shí)(大氣有明顯差別),應(yīng)選用雙頻接收機(jī)。流動(dòng)站可處于靜止?fàn)顟B(tài),也可處于運(yùn)動(dòng)狀態(tài)。GPS的應(yīng)用GPS 最初就是為軍方提供精確定位而建立的,至今它仍然由美國(guó)軍方控制。一些GPS接收器集成了收音機(jī)、無(wú)線電話和移動(dòng)數(shù)據(jù)終端來(lái)適應(yīng)車隊(duì)管理的需要。我國(guó)目前也有一些單位生產(chǎn)車載GPS 系統(tǒng)。(3)發(fā)展GPS產(chǎn)業(yè)今后GPS 將像目前汽車、無(wú)線電通信等一樣形成產(chǎn)業(yè)多元化。用于測(cè)定航空航天攝影瞬間的相機(jī)位置,實(shí)現(xiàn)僅有少量地面控制或無(wú)地面控制的航測(cè)快速成圖,導(dǎo)致地理信息系統(tǒng)、全球環(huán)境遙感監(jiān)測(cè)的技術(shù)革命。(2)地形測(cè)量過(guò)去測(cè)地形圖時(shí),一般首先要在測(cè)區(qū)建立圖根控制點(diǎn),然后在圖根控制點(diǎn)上架上全站儀或經(jīng)緯儀,配合小平板測(cè)圖,現(xiàn)在發(fā)展到外業(yè)用全站儀和電子手薄配合地物編碼,利用大比例尺測(cè)圖軟件來(lái)進(jìn)行測(cè)圖,甚至于發(fā)展到最近的外業(yè)電子平板測(cè)圖等,都要求在測(cè)站長(zhǎng)測(cè)四周的地形、地貌等碎部點(diǎn),這些碎部點(diǎn)都與測(cè)站通視,而且一般要求至少23人操作,需要在拼圖時(shí)一旦精度不合要求還得到外業(yè)去返測(cè),現(xiàn)在采用RTK 時(shí),僅需一人背著儀器在要測(cè)的地形地貌點(diǎn)呆上一二秒鐘,并同時(shí)輸入特征編碼,同過(guò)手薄可以實(shí)時(shí)知道點(diǎn)位精度,把一個(gè)區(qū)域測(cè)完后回到室內(nèi),由專業(yè)的軟件接口就可以輸出所要求的地形圖,這樣用RTK僅需一人操作,不要求點(diǎn)與點(diǎn)間通視,大大提高了工作效率,采用RTK 配合電子手薄可以測(cè)設(shè)各種地形圖,如普通地測(cè)圖、鐵路線路帶狀地形圖的測(cè)設(shè),公路管線地形圖的測(cè)設(shè),配合測(cè)深儀可以用于測(cè)水庫(kù)地形圖,航海海洋測(cè)圖等等。在RTK 作業(yè)模式下,基準(zhǔn)站通過(guò)數(shù)據(jù)鏈將其觀測(cè)值和測(cè)站坐標(biāo)信息一起傳送給流動(dòng)站。單點(diǎn)定位就是根據(jù)一臺(tái)接收機(jī)的觀測(cè)數(shù)據(jù)來(lái)確定接收機(jī)位置的方式,它只能采用偽距觀測(cè)量,可用于車船等的概略導(dǎo)航定位。以及GPS系統(tǒng)信息,如衛(wèi)星狀況等。GPS系統(tǒng)的用戶是非常隱蔽的,它是一種單程系統(tǒng),用戶只接收而不必發(fā)射信號(hào),因此用戶的數(shù)量也是不受限制的。This generally needs to draw support from wireless munication GPS receiver integrated radio, radio telephone move data terminal is it meets need, motorcade of management to e.(2) Appearance of the resource environment of pluralistic spaceAt present, GPS, GLONASS, INMARSAT waits for the system to all possess and navigate to orient the function, formed the pluralistic room resource environment. This pluralistic space environment ,has impelled and fumed a piece of mon tactics internationally and folly, namely on one hand fully utilize the existing system, on the other hand prepare to establish folk GNSS system actively ,by the tome around the2010,GNSS folk system build our purely, the woke world form the tendency that GPS/GLONASS/GNSS stood like the legs of a tripod, could get rid of the reliance on the single system fundamentally, form owning in mon, security resource environment which world shares of can is it is it use realm at most as single navigation means to navigate satelli te to enter. This international and folk strategy, there id influence and force to use the policy to make more omen adjustment to its GPS converselu. Inaword , because of the establishment of the resource environment of pluralistic space ,have created an unprecedented gapped international environment for the development and application of GPS.(3) Develop gaps industryGPS Will form industrialization like the automobile, wireless munication at present in the future, USA strengthen wide area systematic WAAS (namely wide area is it revise date chain transfer to already, it make geostationary satellite it have C? A yards of function too, form wide area the GPS strengthen system of) plan international standard of developing into of. Some units produce carmounted GPS system too at present in our GPS industry of developing our country, already China GPS project centrehas been established in Wuhan.全球定位系統(tǒng)概述摘要:全球定位系統(tǒng)是以美國(guó)國(guó)防為背景,由美國(guó)國(guó)防部設(shè)計(jì)、投資、開(kāi)發(fā)、和運(yùn)行的。 S data storage center, IGS also nearly realtime synthesizes various data processing center the result, and the participant international earth rotation served the IERS global coordinates reference system maintenance and the earth rotation parameter issue. The user also may free online obtain product and so on observation data and precise star experience from internet. The GPS system realtime navigation pointing is very high,US hasimplemented the socalled SA policy in 1992, namely reduces the broadcaststar to undergo the star posi tion precision, reduces the star clock to change thepositive number the precision, adds on the high frequency vibration to thesatellite datum frequency (to cause false distance measuring accuracy to reducewith phase ), latter has implemented the AS policy, soon P yard change is Y yardnamely further limi ts to the prec