【正文】 Summarizing The Global Positioning SystemAbstract: Global Positioning System is based on the background of the United States Department of is designed,invested,developed,and operated by the United States Department of Defense ,GPS is a satellitebased positioning and time transfering GPS positioning function has a wide range of applications in the modern measurement and a more modern technology is also widely used in modernization building, and now GPS has also been shown to be an important civilian munities of interest, and increasingly wide range of applicated.Keyword:GPS,Locating，RTK，Lay out，Survey1. Background The 50s, the former has not launched humanities first artificial earth satellite, the American scientists in along its track research in, had discovered the Doppler shift phenomenon, and has facilitated Doppler satellite navigation posi tioning system pleting using this principle, has obtained the enormous success in the military and the civi aspect, was in a navigation localization history leap, our country once has also introduced many Doppler receiver, applied to the island association measured, the Earth explored and so on the applied to the island association measured, the Earth explored and so on the domain. But because Doppler satellite orbit highly low, signalcarrier frequency low, the track precision enhances with difficulty, causes the pointing accuracy lowly, satisfies the geodetic survey or the project survey request, is more impossible to use in the astronomy Earth dynamics research. In order to enhance the satellite positioning the precision,US started from 1973 to prepare for construction global positioning system GPS (Global Positioning System).After has entered the plan proof, the system test stage,started in 1989 to launch the official work satellite,and pletely pleted in 1994, investment use. The GPS system spaceartially is posed by twenty one satellites, evenly distributes in six orbit, the ground level is 20,000 Kilometers, the inclination of orbit is 55, the flat heart rate approximately is 0, the week contract is 12 hours, the satellite to the earth launching two wave bands intelligence signals,the intelligence signal frequency respectively is mega cycles per second (the L2 wave band), on the satellite has installed the precision very high atomic clock, guarantees the frequency the stability, modulates in the carrier has the expression satellite position the broadcast star experience, use in the range finder C/A code and P yard, as well ad other system information, can in the global scope, to willfully multiuser provide the high accuracy, allweather, is continual, realtime three dimensional measures fast, the three dimensional localization and the time service. The GPS system control section by is located in the American foundations of the states 5 monitoring stations to be posed, these stand did not ask breaks Carries on the observation to GPS satellite, and will calculate and the forecast information by the infusion stands renews to the satellite information. The GPS system user is extremely covert, it is one kind of oneway system,the user only receives but does not need the transmitting message, and therefore user39。 s quantity also is not limited. Although GPS is the unification starts is, but very quantity also is not limited. Although GPS recei ver and processing software emerge in abundance. At present the receiver which appears in the Chinese market mainly has ROGUE,ASHTECH, TRIMBLE, LEICA, SOKKIA, TOPCON and so on.. Can carry on the observation to two frequencies the receiver to be called the double frequency receiver, only can carryon the observation to a frequency the receiver to bee the inference. Says regarding the mapping user, GPS has caused the revolutionary change in the mapping domain, at present, in the scope several thousand kilometers controls network, in the precision from hundred to the millimeter level localization, generally all GPS took the first choice method, is day by day mature along wi th the RTK technology, GPS started to decimeter and even a centimeter level layout, domain seepage and so on high accuracy dynamic localization. The international GPS geodetic survey served IGS with Earth dynamics from 1992, has established many data storage and the processing center in the whole world, year to year observed a station with hundred, our country has also set up Shanghai Yu Shan, Wuhan, Xian, Taiwan and so on many year to year measuring platforms station, these stations observation data passed on every day through the internet net to US39。 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 num