Establishment of Geodetic Coordinate Systems - Geodesy: Introduction to Geodetic Datum and Geodetic Systems - page 373

2. Geocentric coordinates obtained by dynamic satellite geodesy (seven points
nationwide)
3. Global astro-geodetic geoid undulations (referenced to the XAS80)

DX-2 consists of seven transformation parameters. The XAS80 coordinates and
the new BJS54 coordinates can both be transformed into geocentric coordinates
based on DX-2 transformation parameters, and the corresponding system is called
the Geocentric Coordinate System 1988. Thus, DX-2 has two sets of transformation
parameters, i.e., DX-2 new1954 and DX-2 1980 ; the geocentric coordinates obtained are
completely coincident.
The origin of the Geocentric Coordinate System 1988 is the Earth's center of
mass. The Z-axis is directed towards the CIO (BIH1968); the X-axis is directed
towards the international zero-longitude (BIH1968); the Y-axis, Z-axis, and X-axis
constitute a right-handed coordinate system. The unit of length is the meter. If
represented by geodetic coordinates, the ellipsoidal parameters are those of GRS75,
as shown in Table 4.1 .
When the Cartesian coordinates in XAS80 or in the new BJX54 are transformed
into the coordinates in the Geocentric Coordinate System 1988, the formulae for
computation are:

9
=
;

0 Z 00 00 X 00

X D ﾼ X 1 ð þ m Þþ Y ʵ =ˁ Z ʵ =ˁ þ Δ X 0

0 Z 00 00 X 00

Y D ﾼ Y 1 ð þ m Þ X ʵ =ˁ þ Z ʵ =ˁ þ Δ Y 0 , ð 7 : 40 Þ

00
Y

00 00

X

00

Z D ﾼ Z 1 ð þ m Þþ X ʵ =ˁ Y ʵ =ˁ þ Δ Z 0

where X D , Y D , and Z D denote the coordinates in the Geocentric Coordinate System
1988, and X,Y, and Z represent the coordinates in XAS80 or in the new BJS54,
respectively. Their corresponding transformation parameters are DX-2 1980 or
DX-2 new1954 .
It is estimated that the mean square error of each component of the geocentric
coordinate obtained from DX-2 is better than 5m.

7.5.6 China Geodetic Coordinate System 2000

Since the 1980s, under the concerted efforts of the Chinese State Bureau of
Surveying and Mapping (SBSM), the Surveying and Mapping Bureau of the
General Staff Headquarters (SMBGSH), China Seismological Bureau (CSB), Chi-
nese Academy of Sciences (CAS), and some other units, China has established in
succession first- and second-order nationwide GPS networks, order A and B
national GPS networks, GPS continuously operating reference station (CORS)
networks, and Crustal Movement Observational Network of China (CMONOC).
A large-scale combined adjustment between terrestrial and spatial networks has
been carried out. These achievements have marked the mature technological