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2014-10-23 18:20:31????Դ: ?????̳?????ߣ?
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ժҪ????????Ҫ??ʲô??????????????????GPS???ǵĹ㲥????????????????????GPS?㲥???????Ե??㶨λ??Ӱ?켸???????˽?????????֪ʶ??ͨ?????ģ??????˶?GPS?????????ʶ???˽⡣ ?ؼ??֣?????   ?㲥????  ????????  ???   һ??ʲô?????????????????????䶨??????? ???????????ֳ?Ϊ???й?????ݣ?TLE??Two-Line Orbital Element??????????celestrak??????????     ??????????????????̫?շ?????λ?ú??ٶȵı???ʽ———????ʽ???????ϵͳ?????ǡ??????????????һ??????̫?գ?????????NORAD???????????Ŀ¼??????NORAD???????????Ŀ¼??̫?շ????彫?????????١????ǡ?????к??ȷ??????Ϊ̫??????ʱ???Ա?????NORAD???DZ??Ŀ¼??ֱ??Ŀ????ʧ???????????Կ????ն??ɵ?6 ?????????֮?????ѧ??ϵȷ?????????ʱ?䡢???ꡢ??λ???ٶȵȸ???????????м??ߵľ??ȡ??????????ܾ?ȷ???㡢Ԥ?⡢??桢???????ǡ????????ʱ?䡢λ?á??ٶȵ?????״̬???ܱ??????塢???ǡ???????????????̫???????ȷ?????ľ?ȷ???????ܽ?????????????ά?Ŀռ䣻??ʱ?????????????Ĺ?ȥ?????ںͽ???????????????ʱ?䰴?????׼ʱ?䣨UTC?????㡣     ??????????ʱ???¡?     ??????????Ӧ???ھ??¡????ġ????졢????????Ԥ?⡢??λ??????????١???????̫???????ļ??㡢Ԥ?⡢??桢???١?   ?????????????????????????õ??????ǵĿռ?λ????ʵ??λ??֮???Ϊ?????????? ???????????ɵ?????վ???ټ???????󶨵ġ???????????????Ҫ?ܵ??????㶯???ĸ???Ӱ?죬??ͨ????????վ?????Գ?ֿɿ??زⶨ??Щ?????????????????ù??ɣ??????????Ԥ??ʱ??????ϴ??????һ???۲?ʱ????ڣ????????????ϵͳ????һ??????????????????????Ӱ?쵥?㶨λ?ľ??ȣ?Ҳ?Ǿ?????Զ?λ????Ҫ?????Դ??   ?????????Խ??Ƶ???Ϊ???ߵ???Ծ??Ƚ??Ƶص???????????Ծ??ȣ??????????߶? 20200km֮?ȣ??????ϸ???ԣ????????Ի??ߵ?Ӱ???????Ǻͻ??ߵ???Լ??ηֲ??йأ????Ѿ?????????С?????۲???????????4??ʱ??????????Ӱ?콫???ؼ?С??   ?㲥?????;?????????????????GPS???Ƕ?λ?е???Ҫ???ݡ???????????????????????λ???????ǵ?ʵ??λ??֮???Ϊ??????????GPS???ǵĹ㲥????????ȫ??λϵͳ?ĵ?????Ʋ?????ȷ?????ṩ??,??GPS??????ȫ???????û???????????һ??Ԥ??????,?侫?ȽϲSA????ȡ????,?㲥???????????????ǵĵ?λ?????Ϊ5~7m??   ????GPS???ǵĹ㲥??????????? ?㲥?????Ƕ?λ???Ƿ????????ߵ??ź???????Ԥ??һ??ʱ???????Ǹ????ĵ?????Ϣ?? ?㲥?????ľ????Ǽ????ȶ??ģ????????????䡢????Ƿ???????Ƿ??ڵ????????????Ӱ???Ⱥܶ???û???????żȻ???ص?Ӱ?죬??ʹ????SA???ߣ??㲥????Ҳ???ܻ???? 1(Xhn????۲?һЩ????????߾??ȡ??????CPS???ǹ??ʱ???㲥????ֻ??ȷ????ֵ?????ã?lOOm?ľ?????ȫ?㹻?ˡ????????˶???ģ?͵??????𶨳?????????????ڳ????붨λʱһ??Ӧ???þ?????????ͬʱ???졣   ?㲥????????ǵ?ǰGPS??λ????Ҫ?????Դ֮һ??????SA????ȡ????,GPS???ǵĹ㲥????????GPS?????Լ????º??ز???λ???GPS???ݾ??ȵ?Ӱ??̶Ⱦ??????,??ȱ?????ݵ??????ֻ????????????????ṩ?Ĺ???ֵ,ͨ?????۷??????º????ݴ????ķ????Թ㲥???????Ӱ??GPS???㼰?º??ز???λ˫?λ???ȵij̶?չ???о???     ???????????? ?????????????Ǿ??ܶ?λ??ʹ?õ????ǹ????Ϣ?????????????????????Ǹ???վ?Ĺ۲????ݣ????º?????õĹ????Ǿ??ܶ?λ??ʹ?õ????ǹ????Ϣ??   ??????????Ϊ?????ز???????????ѧ?о??Ⱦ???Ӧ?????????Ҫ?????ơ???????һ?ָ߾??ȵ??º???????Ŀǰ??GPS??????????Ҫ??????:????????????ͼ??(DMA)?????ľ????????Լ??ɹ???GPS????IGS(International GPS Serv-ice)?????ľ?????????ǰ?ߵ?????????ԼΪ2cm,???ߵ?????????ԼΪ5cm?????þ???????ʱӦ??ע?⣬???? GPS???ϴ????????ṩ?ľ???????????????ֵ?Ϻܽӽ????????ڸ??Բ??õ??????˶???ģ ?Ͳ?һ?£????ܻ?Ի??߽??????ϵͳ?ԵIJ???.   ?ģ??й??????????????????   GPS?㲥?????Ĺ???????? ?????????????Ƕ?λ??ǰ??ͻ????????????ȵĺû???ֱ??Ӱ?춨λ?ľ??Ⱥͽ????GPS?㲥??????Ȼ???ȽϾ????????ͣ?????Ϊ?????ʵʱ???׻?ȡ???ص㣬?ѱ??ڶ?ʵʱ?????Ͷ?λ?û????㷺ʹ?á?David L.M. Warren??John F. Raquet??1993?굽2002???ڼ??GPS?㲥?????Ĺ??????????????˷??????õ???һЩ????Ľ??ۡ?2002?꣬Ϊ?????GPS?Ķ?λ???ȣ?NGA(National Geospatial-Intelligence Agency)??AII??һЩ?Ľ??ɹ?Ӧ?õ?????վ?ϣ???NGA??JPO֧?ֵ?????ƻ????ճɹ?ʵ?У???L-AII??Legacy Accuracy Improvement Initiative???ƻ???????Ҫ????[4]???ٽ?NGA?۲?վ??GPS???ǽ??и??ٹ۲?????????ӵ????Ƕ??졢Ԥ???????У????Ҽ???Ĺ۲?վ??Ŀ?᲻?????ӣ??ɿ?ʼ6??վ?????11??վ??ʹ?????е?GPS??????????ʱ????????һ?????????վ??????й۲⡣????ǰ??GPS???и??ٹ۲??ֻ??OCS??5?????վ???ڶ????Ƕ???/?ƹ?????????ʹ?õĶ???ѧģ?͵ĸĽ????Լ???????single partition????????Ե?ʵ?С?  ?ڸ???????Ŭ???£??ر???L-AII?ƻ???ʵʩ???㲥?????Ĺ?????????˺ܴ????ߣ??ӳ????????п??Կ??????????????ϵ?ƫ?????ƽ??ֵ???ӽ???0???Զ?λ????Ӱ?????ľ????????վ?????????2002???0.8m???ҽ??͵???2006???0.6m???ң?????????Լ????????Ҳ?ֱ???2002???4m??2.5m???ҽ??͵???2006???1.5m??0.9m???ң????ڲ??????Ӳ??????£?SISREҲ??1m???ҽ??͵??ӽ???0.7m????2006??׼??????????ǵ???άƫ???RMS???ﵽ??2m???ҡ??????ڴ?????????ػ????Ľ?һ??Ŭ???£??Լ????ܸ?Ϊ??????????ǵ?½?????գ?GPS?Ĺ㲥?????Ĺ?????Ƚ???õ?????һ??????ߡ?   GPS?㲥???????Ե??㶨λ??Ӱ?? ?ڵ??㶨λ??,???????????Խ?????Ӱ??ϴ?.??ͨ???㶨λ?????ܵ??㶨λ????ѧģ??,ͨ???㲥?????????????????ݵĽ???,???????????ȶԵ??㶨λ??Ӱ??.??????????,ʹ?ó??????????????վ??ܽ??о??ܵ??㶨λ?ǿ??е?.   IGS???????????????? ???ø߾??ȵ?ITRF2000ȫ??ο???ܡ??µĵ???????ģ?ͺ???????ģ?͡?ͳһ?????ǹ???????͵?????תģ?͡?ͳһ?????ݴ??????ԣ????´?????IGSȫ?????վ?????????1994—2004???GPS???ǹ????ͨ??????Ƚ???????IGS??????????ϵͳƫ????????????IGS??????????ƾ??Ⱥ?ʵ?ʾ??ȴ??ڲ??죬?ر??????ڽ????IGS?????????ڲ?ͬʱ?ڴ??ڲ?ͬ??ϵͳƫ???Ҫ?????ڲ?ͬʱ?ڲ??õIJ?ͬITRF???вο????֮??IJ???????IERS??????ת????????????ȫ????ITRF???м?IJ??졣??????ؽ⾫ȷ?????IGS????????????????ʱ???𽥼?С??1994??Ϊ15—20cm??1998???𽥼?С??6??8cm??1998???Ժ?С??5cm??   ???????ͨ????һЩGPS????֪ʶ?????????????׵IJ????????ó????????????????о??˽??µķ??????????۷????????˵Ĺ۵㣬?????˶?GPS??????????⡣   ?ο????ף? ??GPS?㲥?????Ĺ????????????????????????            ??GPS?????????ݴ???????????
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