1、中文 3252 字 附录 A:外 文文献 Development of new geodetic coordinate datum management system Abstract： Current situations of geodetic coordinate datum development procedures and China were presented The precisions of astronomic geodetic network and space geodetion Geodetic datum requirements under the curren
2、t and future new surveying technologies and their applications were discussed The necessity for upgrading national astronomic geodetic network and development of a new open coordinate geodetic datum management method was investigated Key words： Geodetic Datum； Geodetic Network； Management INTRODUCTI
3、ON Coordinates are the reference for surveying and mapping The development for a high quality coordinate datum is one of the important tasks for surveyors over the world and also a reflection to the survey technologies in state Currently， World Geodetic System 1984(WGS-84)is the most popularly used
4、coordinate system internationally There are two nationally used coordinate system， in 1954 Beijing system and 1980 Xian systern There are lots of local coordinate systems developed with different methods in some areas Considering the importance of coordinate system， a high quality coordinate datum w
5、ith modern management method is essential 1、 GEODETIC COORDINATE SYSTEM STATUSIN CHINA At the beginning when founding our state former Soviet Union Krasovskys ellipsoid was used for the development of reference coordinate system The origin of this system was in former Soviet Union The iointly survey
6、ed coordinates of former Soviet Union geodetic coordinate network and the three points at Huma， Jilalin， and Dongning in Northeast of our country were taken as our astronomic starting reference data Then a point in Beijing was calculated accordingly and was so called 1954 Beijing coordinate system S
7、ince the founding of the state， a lot of surveying and mapping tasks were completed with this coordinate system despite some problems existed due to the technological restrictions at that time These prob1ems are： （ 1） The reference ellipsoid semi-major axis is more than 100m longer than modern preci
8、sely surveyed size （ 2） The reference ellipsoid used is not identicall with the geoid of our counter The elevation abnormity in Eastern is as high as 68 m （ 3） The ellipsoid reference axis direction is not precisely defined （ 4） Error accumulations are large and accuracy is low To overcome these pro
9、blems and provide better services for economic development， national defence， and geodesy as well as space research， the Nation al Surveying Bureau did adjust in one cast to national astronomic geodetic network in the end of 1970s and the beginning of 1980s The 1980 Xian coordinate system was develo
10、ped IUGG-75 ellipsoid was used in this system The difference between ellipsoid and geoid is within 4-20 m and the side accuracy is 1/500 000 after adjustment A new geodetic coordinate system is planning to meet the scientific needs in our country as the developments of new technologies such as very
11、long base interfere(VLBI)and global positioning Systems(GPS) The classes A and B GPS network were completed and put in use respective in 1996 and 1997 The space geodetic network developments entered a new phase with these progresses It is not only with higher accuracy than former systems but also wi
12、th three dimension coordinates which developed on internationaly defined ITRF frame This high accuracy 3D space geodetic coordinate system will guarantee the infrastructure surveying for the first 10 years of twenty-first eentury After adjustment， the plate coordinate overlap accuracy of class A GPS
13、 network is better than 210。 Elevation accuracy is better than 710 Absolute accuracy is better than 41.2 m For class B network， these accuracies are better than 410， 810， and 1 m， respectively The completion of national class A and class B geodetic control network indicates that we have developed de
14、cimetre absolute 3D geodetic control net work A new reference system is available for our space technology， and spatial data as well as real Proceedings of ISM 12th International Congress time dynamic positioning A lot of local coordinate systems were developed besides national plane coordinate syst
15、em These systems served national economic developments in some sense Considering the importance of coordinate system to economic developments and national defence， coordinate system factors are confidential data The national and local governments control the geodetic coordinate factors strictly and
16、data processing is also charged by relative government agencies 2 MODERN SURVEYING TECHNOLOGY REQUIREMENTS FOR COORDINATE SYSTEM MANAGEMENT Requirements with advances and applications Of GPS GPS has been playing an important role in surveying and mapping from 1990 s and the accuracy is getting bette
17、r The US GPS real time positioning accuracy is 3 m As a military targeted system， SA was carried out on the beginning of GPS system and was removed on May 2000 to meet its economic benefits The US government provides higher accuracy of 30 m from earlier 100 m total standard users A new Global Naviga
18、tion Satellite System(GNSS)was in March 26， 2002 by European Union(EU)to meet their own benefits Galileo is a program independent of US GPS developed by EU According to its plan， Galileo program will include 30 satellites with four phases The first phase is system evaluation period(completed in 2000)； the second phase is development and test period(from 2001 to 2005)； the third phase is implementation period(2006 to 2007)； and the fourth phase is commercial
