【正文】
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 measuring platform already can constitute millimeter level the global coordinates frame. 3. RTK technologies The conventional GPS measuring technique, like the static state, the fast static state , the dynamic survey all~eed afterwards to carryon the solution to calculate can obtain a centimeter level the precision, but RTK is can realtime obtain the centimeter level pointing accuracy in the open country the measuring technique, it has used the carrier phase dynamic realtime difference (Realtimekinematics) the method, is the GPS application significant milestone, its appearance for the project layout, the terrain mapping, each kind of control survey has brought the new dawn, enormously enhanced the field operation work efficiency. The high accuracy GPS survey must use the carrier phase observation value,the RTK localization technology, it can realtime provide in assigns in the coordinate system the three dimensional localization result, and achieves the centimeter level precision. Under the RTK work pattern, the datum stands through the data chain transmi ts together its observation value and the survey station coordinates information for the mobile station. Mobile stands not only receives the data through the data link which stands from the datum, but also must gather the GPS observation data, and poses the difference observation value in the system to carryon the realtime processing, simultaneously produces the centimeter level localization result, a lasted. The mobile station may be at the static condition, also may be at the state of motion。 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 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 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。 May first carryon the initialization after the fixed point to enter the dynamic work again, also may under the dynamic condition directly opening machine,and pletes the week fuzziness search solution under the dynamic environment. After end knows the number solution to be fixed, then carries on each calendar Yuan realtime processing, so long as can maintain four above satellites phases observation value the track and the