【正文】 ber 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 precise false distance survey, but American military and special permission user not these polices influences, but US in order to obtain the bigger mercial interest, these policy ends are cancelled. 2. GPS localization principal The GPS receiver may receive and use in the time service accurately to the nanosecond level time information。 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)。 As well as GPS system information, like satellite condition and so on. The GPS receiver may obtain the satellite sign to the code to the receiver distance, because includes the receiver satellite clock the error and the atmosphere propagated error, therefore is called the false distance. The false distance obtains which to the OA code is called the UA code false distance, the precision approximately is about 20 meters, obtains the false distance to P yard to be called P yard false distance, the precision approximately is about 2 meters. The GPS receiver to the satellite signal which receives, carries on the decoding or uses other technologies, will modulate after the carrier the information removes, will be allowed to restore the carrier. Strict says, the carrier phase should be called the carrier beat frequency phase, it is receives produces the Doppler shift influence satellite signal carrier phase and receiver this machine vibration difference of the signal phase. Generally experience Yuan time which determined in the receiver clock surveyed, maintains to the satellite signal track under, may record the phase change value, but starts time the observation receiver and the satellite oscillator phase change value is does not know, namely misty degree of whole week, only can calculate in the data processing as the parameter solution. Phase observation value precision high to millimeter, but the premise is solves misty degree of whole week, therefore only has when the relative localization, and has a section continuously observes the value can use the phase observation value, but must achieve meters down to themillimeter level also only to be able to use the phase observation value. According to the locate mode, the GPS localization divides into the simple point localization and the relative localization (difference localization). The simple point localization is according to a receiver observation data determined the receiver position the way, it only can use the false distance view survey, may use in Chef Chuan and so on the summary navigation localization. The relative localization (difference localization) is according to two above receivers observation data determined between the observation point the relative position method, it already may use the false distance view survey also to be possible to use the phase view survey, the geodetic surveyor the project survey should use the phase observation value to carryon the relative localization. Has contained the satellite and receiver ZhongChai, the atmospheric dissemination in the GPS view survey retards, error and so on multipart effect, when localization error the influence, when carries on the relative localization the majority of public errors are counterbalanced or weaken, therefore the pointing accuracy greatly will enhance, the double frequency receiver will be allowed to act according to two frequencies in the view survey counterbalance atmosphere the ionospherepath error main part, will request high in the precision, between the receiver the distance wi11 be farther when (atmosphere will have obvious difference), will be supposed to select the double frequency receiver. When localization observation, if the receiver is opposite to the earths surface movement, then is called the dynamic localization, like uses in summary navigation localization the and so on Chef Chuan precision is 30100 meter false distance simple point localization, either uses in the city vehicles navigation localization rice level precision false distance difference localization(RTK), the realtime difference localization needs the data chain realtime transmits two or many stations observation data calculates together. When localization observation, if the receiver is opposite to the earths surface static, then is called the static localization, when carries on controls the net observes, generally selects this method by several receivers also to observe, it can maximum limit display GPS the pointing accuracy,specialpurpose Yu Zheizhong the goal receiver is called the earth receiver,is in the receiver a performance best kind. At present, GPS already could achieve the earths crust performance observation the precision request, IGS year to year the measu