MINISTRY OF EDUCATION AND TRAINING
HANOI UNIVERSITY OF MINING AND GEOLOGY BUI THI HONG THAM

RESEARCH ON THE THEORETIC BASE FOR THE
MODERNIZATION OF THE NATIONAL GEODETIC
CONTROL NETWORK IN VIETNAM BY GLOBAL
NAVIGATION SATELLITE SYSTEM GNSS
Specialty: Geodesy and Mapping
Code: 62520503
SUMMARY OF THE THESIS SUBMITTED FOR THE
DEGREE OF DOCTOR HANOI – 2014
The thesis has been completed at the Department of Geodesy
surveying, of Surveying Faculty, Hanoi University of Mining and
Geology.

Scientific Supervisors:
1. Prof. Dr.Sc. Dang Hung Vo
Association of Geodesy, Maps and Remote Sensing of Vietnam
2. Dr. Vu Van Tri

Currently, national coordinate network in the world are ordinarily
built on GNSS continuously operating reference stations with
consistent density, appropriated accuracy, reliability, safety and multi
– purposes. This is called the GNSS CORS network. The name
describes technologically "continuous observation to connect points in
an online network system." Density and distribution of points varies
from country to country.
In Vietnam, the traditional network was upgraded preciseness,
improved and modernized by GNSS technology to become national
georeference system VN - 2000. This made a milestone of surveying
and mapping science of our country.
In face of the achievements in the world, it is essential to build
continuously the geodetic coordinate network by GNSS technology to
replace traditional geodetic network and meet the modern demands of
the coordinates. GNSS technology applications are the most basic
component of geographic information infrastructure and become a
trend in the world, so we have to integrate without any other options.
The Ministry of Defense has been executing the project of
constructing the military georeference system GNSS CORS network
(finished on 1/2 block workflows), Ministry of Natural Resources and
Environment has built and implemented Strategy of measuring and
mapping development, of which the modernization of coordinates and
leveling network system is the main point (consideration to approval).
Although there are scientific basis and practical studies to apply, there
has been no thesis which does research in a systematical way of
2
building modern geodetic coordinate network, multi-purposes to meet
the demand and integrate development of geographic information in
the world. "Research on the theoretic basis for the modernization of
the national geodetic control network in Vietnam by global

methods, especially the group of methods to measure real time area.
- The format (structure and density) GNSS CORS network
serving the purpose of geodesy and mapping (basic terrain mapping,
3
cadastral and construction), monitoring crustal movements, building
the national reference system according to the dynamic point of view.
- Process data of measurements of national GNSS CORS network
simultaneously with IGS data to link international coordinates, update
on coordinates according to the dynamic reference system point of
view, and observation of modern crustal movements.
6. The methodology
The dissertation using the following methodologies:
- Methods of synthesis, analysis and inheritance: Collect the
historic documents; update the information on the internet, synthesis,
analysis of resources and research results, inherit selectively
achievements related to the subject.
- Methods of collection and processing GNSS data: static
measurements, session 24/24 at the continuous measurement points.
Processing of measurements and IGS data by Bernese 5.0 software,
connect coordinates, velocities with IGS network, scalability
coordinates, and velocities in the typical dynamic coordinates system
ITRF.
- Methods of comparisons: Compare the advantages and
disadvantages of building geodetic control network according to the
traditional method and the method using GNSS technology.
- Methods of expert: Learn more knowledge and experience from
experts.
- Method of application of information technology: using
programming languages; setting up spreadsheets to automate the
calculation process.

b. New contributions
- To put forward a GNSS CORS network in Vietnam with full
scientific and practical foundations.
- To prove the necessity of building a dynamic reference system
in Vietnam by specific data.
- To propose the time to update the new coordinates for the GNSS
CORS network in Vietnam.
- To put forward the workflow of coordinate transformation,
velocities of GNSS points between international terrestrial reference
frames ITRF using 14 transformation parameters.
- To establish the velocity diagram of GNSS points in Vietnam in
a coordinate system.
9. Structure of dissertation
The structure of dissertation includes three main parts:
introduction, content as well as conclusions and
recommendations, which is presented on 132 pages, 25 drawings
and diagrams, 34 tables.
5
Chapter 1
OVERVIEW OF APPLICATION OF GPS TECHNOLOGY
IN BUILDING COORDINATE NETWORK SYSTEM
1.1. Application of GNSS technology in the construction of
geodetic network in the world
GNSS has become a major technology and has gradually replaced
the traditional measurement technology in the construction of geodetic
network.
1.2. Application of GNSS technology in the construction of
geodetic network in Vietnam
From the overview picture of the development of GNSS
technology in the world and the process of applying GNSS technology

2.1. The general problem
2.1.1. Conception changes of form, structure, precision of control
network since the GNSS technology was born
- Changes of the application structure of GNSS

Figure 2.1. The application structure of GNSS technology [50]
Currently, there have been fundamental changes in GNSS in terms
of technology on promoting positioning under the new approach. With
the present concept, the application structure of GNSS technology is
expanded (Figure 2.1).
- Development trends of measurement methods.
The principle of measuring real-time NRTK starts with all
reference stations in these network online observing satellites
continuously with the software system installed on the master system
of NRTK center.
GNSS
Augmentation system
User segment
Basic system
Control
segment
SBAS
receivers
software
Space
segment

GPS
GLONASS
GALILEO

As a result, geodetic control network under standpoint ensures the
capacity to provide data about the shape, size, gravity field of the
Earth, as well as the volatility of quantities over time. This network
has the following tasks:
- Navigation and tracking: error millimeters.
- Surveying and mapping: error position about centimeters.
- Research and identify crustal movements: error millimeters.
- Supporting research atmosphere,
2.1.2. The method of construction GNSS CORS network playing
basic geodetic plane network in the world and Southeast Asia
Today, so many GNSS CORS networks have been established in
the world, which are the major infrastructure to provide the necessary
applications with high accuracy in surveying, mapping, navigation and
the Earth science applications. The countries which have set GNSS
CORS network have to follow the legal and the rules of the countries.
Moreover, the countries with great potential of sharing the network
also cooperate to form GNSS CORS networks of the region.
8
2.1.3. Some features when building GNSS CORS network
The main advantages of the GNSS CORS network: reducing
depended error sources due to the connection of the permanent stations
to produce the network, the longer distances of points in the GNSS
CORS network results in decreasing the number and density of the
points, and automating the GNSS measurements referencing ,
calculation results to unified reference frame.
2.2. The ability to change the horizontal control network in
Vietnam by the method of construction GNSS CORS network
The control plane network in Vietnam in the future will be the
GNSS CORS network (NRTK CORS), which has distance and
appropriate accuracy to satisfy most missions.

78
6
80
5543
60
7
90
7015
47
8
100
8660
38
9
150
19486
17
10
200
34641
10
11
250
54127
6
2.3. Construction GNSS CORS network in Vietnam
2.3.1. The idea of the tier the national GNSS CORS network,
structure, density and accuracy
The idea of construction GNSS CORS network in Vietnam must
be multi-purposes network service, and satisfy most missions

To connect with IGS, the network has some
points of attributes IGS to resolve international
scientific tasks regionally and globally
about mm
To form the national GNSS CORS network serving multi-
purposes, the ideas of designing network are proposed:
- Calculation 0f number of points in the GNSS CORS network
bases on missions and accuracy requirements of each tier in the
network.
- The sum of the national GNSS CORS network is calculated
when this network satisfies the requirements of measurement basic
maps - the third GNSS CORS stations.
- Some of the third GNSS CORS stations will be selected to meet
the mission of the first and the second GNSS CORS stations.
- Some of the second and the third GNSS CORS stations will be
selected to meet the mission of the first stations.
- One GNSS CORS station is able to satisfy many different tasks.
Table 2.3. Recommended the number of GNSS CORS stations
Vietnam
Area
(km
2
)
Distance
(km)
Control area of a
GNSS CORS
(km
2
)

* Comment
Figure 2.2 shows that the application of GNSS technology has
changed the traditional network in both structure and density. The new
one is multi-purpose network; satisfies the requirements of modern
surveying; guarantees for solving the task of verifying and maintaining
the reference frame, coordinate system; satisfies the requirements of
measurement basic mapping; navigation and tracking; researching
modern crustal movements.
79 points in the national GNSS CORS network are designed on
the base map of Vietnam. Some points in the network serve many
objectives when building the GNSS CORS (eg. points in MongCai
cover five functions: join IGS, build the national geodetic reference
frame, research modern crustal movements, navigation and tracking
and serves basic mapping).
In the process of building the national modern geodetic network,
some points in VN - 2000 satisfying the requirements will be selected
as the points of the national GNSS CORS. These points in two
networks will serve for the determination of coordinate transformation
parameters. This will ensure that close link between the old and new
network as well as the unified use of two networks.
The above analysis proves the capacity and accuracy of GNSS
technology in the current period, shows technical efficiency (improves
11
the accuracy and expands the technical scope, timely updates,
automation, ) indisputable of this technology when applied for the
construction of the national geodetic network in Vietnam.

Figure 2.2. The GNSS CORS network in Vietnam
Note: : Function set up the national reference frame; :
Research function geodynamics; : DGPS function; : Joined on


12
0

8
0

TRUNGQUOC
THAILAN
Hainam
HoangSa Islands
(Vietnam)
CAMPUCHIA
MALAYSIA
TruongSa Islands
(Vietnam)
12
Chapter 3
THE NATIONAL HORIZONTAL NETWORK FOR MORDEN
CRUSTAL MOVEMENTS RESEARCH
3.1. Scientific and practical significance of researching modern
crustal movements in intercontinental and global scale
Over time, GNSS technology is growing and perfect, problems of
geometry and physics of the Earth is resolved. Until now, this
technology has completely satisfying scale of studies, the accuracy
required for the job posting. This is the basis to take form concepts of
dynamic geodetic.
3.2. The network monitors modern crustal movements and
achievements when applying GNSS technology
The determination of the Earth's crustal movements requires the

x
x

x
x
x
x
2
2/12/2010
336
x
x
x

x
x
x
x
3
3/12/2010
337
x
x
x

x
x
x
x
4

x
x
13
7
3/6/2011
154
x
x
x
x
x
x
x
x
8
4/6/2011
155
x
x
x
x
x
x
x
x
9
5/6/2011
156
x
x

63
x

x
x
x
x
x
x
13
4/3/2012
64
x

x
x
x
x
x
x
14
5/3/2012
65
x

x
x
x
x
x

-1521499.8762
6094084.7056
1104443.9268
4
TSRS
-2354092.2732
5850302.4095
952491.9085
Table 3.3. Absolute velocity of points DGPS/CORS
N
0
Point
V
B
(mm/y)
V
L
(mm/y)
V
H
(mm/y)
V
(mm/y)
Azimuth
(
0
)
1
DNRS
34.7

- Thus, the national DGPS CORS network has been computed
processed and connected to IGS. Measurement and support data were
selected to fully satisfy the task of establishing geodetic reference
frame and identify modern crustal movements during the processing.
- The process was carried out according to strict procedures.
- The velocity of points: MCRS (MongCai), DNRS (DaNang),
PQRS (PhuQuoc) and TSRS (TruongSa) determined by the integration
of standard equations is about 3 cm/year. Error of the vertical and
latitude, longitude velocities are approximately 3 mm/year and 1
mm/year, respectively. The result is high accuracy in comparing to the
3 cm velocity.
- Movements in the different regions of the territory are various:
40.3 mm/year in the Central region (the largest value), and the velocity
movement in the MongCai is faster than PhuQuoc and TruongSa 31.8
LAO
TRUNGQUOC
THAILAN
HoangSa Islands
(Vietnam)
CAMPUCHIA
MALAYSIA
TrươngSa Islands
(Vietnam)
(TB-BTB)
(NTB-NB)
Hainam
(ĐB
)
(MT
)

30 mm/year
MALAYSIA
15
mm/year. The modern crustal movements are similar in PhuQuoc area
and TruongSa Islands.
- The velocity vectors indicated the study area tends to movement
towards Northwest – Southeast connecting to the other published
results both in direction and value.
- In addition, the results also give the coordinates of the points in
the ITRF05 reference frame related to international time 2010 - 03-04
00:00:00. The software also allows determining coordinates in relation
to any selected point.
- The velocity vector obtained through the processing practically
of the dissertation is recognized as a scientific contribution to research
modern crustal movement map on the territory of our country.

Chapter 4
CONSTRUCTION OF THE NATIONAL HORIZONTAL REFERENCE
SYSTEM ACCORDING TO DYNAMIC POINT OF VIEW
4.1. The process of forming the dynamic geodetic reference system
in the world
The implementation of the ITRS is to determine International
Terrestrial Reference Frame (ITRF) with 7 parameters including 3
parameters of original geocentric, 3 of axis orientation angle
parameters and 1 parameter of the difference in length. These
parameters are updated base on the observation data every year. It is
necessary to consider the rate of change of the 7 parameters because
they are always in a state of dynamic (Earth exists in the dynamic)
.Thus, a number of parameters is 14.
4.2. The necessity of the construction of the dynamic reference

d
max
1
8.5
15.9
16
16
2
17
31.8
32
32
3
25.5
47.7
48
48
4
34
63.6
64
64
5
42.5
79.5
80
80
6
51
95.4

period of updating the coordinates of the GNSS CORS network is
reasonable by calculation specifically. There are two reasons for this;
firstly, if the update of coordinate is not done, the GNSS network will
be deformed and do not guarantee the accuracy of the measurement of
basic maps; secondly, if its updating is always done so difficult for
measurement mapping, economically costly.
To propose the updating time for the new national coordinate
GNSS CORS network guaranteeing for surveying terrain mapping
1:500 in all conditions (barren or bushy area), the dissertation choices
maximum error 100 mm.
The deviation presented on table 4.1 shows that movement
velocity of the largest annual tectonic blocks in the 6
th
and 7
th
years are
96 mm and 112 mm, respectively; meaning the velocity in 7
th
year
(d
max
) is greater than 100 mm. Therefore, the interval of time required
to update the new coordinate for the national GNSS CORS network is
recommended 7 years.
4.3. Construction of the dynamic reference system in Vietnam
The GNSS CORS network is the realization of the national
coordinate system according to the dynamic view. This network will
maintain the national geocentric coordinate frame 3D and support for
in real-time positioning, navigation and monitoring applications. In
addition, measuring precision leveling, measuring gravity points in its

(t - t
0
)

)2(
ITRFZYX
)V,V,V(

)2(
ITRFZYX
)V,V,V(

)2(
ITRFHLB
)V,V,V(

)1(
ITRFHLB
)V,V,V(

X(t
0
)
(1)
X(t)
(1)
)1(
ITRFHLB
)V,V,V(


X (m)
Y (m)
Z (m)
1
XUYO
-1606525.3107
5700807.4794
2358910.3445
2
OAN0
-1566459.7943
5711793.1162
2359391.0194
3
DOI0
-1554911.1281
5722287.9981
2341248.9526
4
SOC1
-1621267.4901
5719456.3583
2303158.3259
5
TAM2
-1601083.2914
5719707.1284
2318672.4007
6
HUN1

-1480436.1083
5741958.4656
2342822.2803
13
NGA1
-1353072.7825
5749668.0049
2402462.2895
14
HAM1
-1355321.3541
5762376.1094
2367436.5756
15
DON1
-1334851.1103
5758491.9047
2387972.1199
16
LEM1
-1335854.0006
5773067.2098
2353215.1336
17
MON1
-1464209.0062
5767238.2661
2291232.1061
18
NOI1

-1726969.5917
5714864.9568
2237081.3908
25
NT03
-1844373.6094
5997105.5965
1142317.0439
26
NT04
-1575936.5479
6075089.2127
1132070.0742
27
QT01
-1339440.8883
5788398.0139
2313170.2549
20
28
QT03
-1916791.4419
5822974.9368
1754668.6848
29
VUNT
-1849617.0276
5995299.9136
1143372.7201
30

ITRF08
N
0
Point
V
L

(mm/y)
V
B

(mm/y)
V
H

(mm/y)
V
(mm/y)

Azimuth
(
0
)
1
XUYO
-10.8
35.1
0.6
36.7
107.1

-10.0
33.2
-5.1
34.7
106.8
7
NTHO
-10.5
33.4
-10.6
35.0
107.4
8
SON1
-10.4
32.9
-3.6
34.5
107.5
9
LAP1
-10.9
33.0
-4.7
34.8
108.3
10
BAVI
-9.4
32.2

104.9
15
DON1
-10.4
35.3
15.3
36.8
106.4
16
LEM1
-9.4
34.9
12.0
36.2
105.1
17
MON1
-11.7
32.5
-1.0
34.6
109.8
18
NOI1
-10.4
33.1
-4.3
34.7
107.4
21

-8.0
27.6
16.7
28.8
106.2
24
NT01
-11.7
36.3
7.6
38.1
107.9
25
NT03
-11.7
27.1
18.8
29.5
113.4
26
NT04
-9.8
15.9
-14.5
18.6
121.6
27
QT01
-10.3
30.2

115.7
32
BLO1
-14.1
24.1
2.6
27.9
120.3
33
ALO1
-15.4
29.5
19.5
33.2
117.6
34
LNI1
-13.5
26.1
3.9
29.4
117.3
35
THN1
-13.2
25.5
2.7
28.7
117.4
36

21.9
-7.5
24.2
115.2
41
CDA1
-7.4
20.7
-9.6
22.0
109.7
42
HOCM
-11.5
22.0
-3.0
24.8
117.6
43
CAMP
-4.4
47.7
28.1
47.9
95.3
44
NONN
-0.2
44.5
24.6

22
* Establish diagram the absolute movement velocities on the
territory of Vietnam
coordinates and velocity of some GNSS points on the territory of
Vietnam transferred from ITRF94, ITRF00, ITRF05 to ITRF08 on
18
th
, july7, 2012 base on Vietnam and international data. The results
are shown in Figure 4.3. The transformation method allows applying
to coordinate and velocity between the dynamic national reference
frame (eg. tied to ITRF).
This result is not only theoretical but also practical contribution to
the study of modern crustal movements and construction of the
dynamic coordinates system in future in our country.

Figure 4.1. The diagram of movement velocities of GNSS points LAO
16
0

104
0

108
0

112
0

(1) The dissertation gives overview of infrastructure development
process of geodetic engineering in the world and Vietnam.
Construction of the GNSS CORS network and the support techniques
is a vital trend of all countries to reach the real-time kinematic and
multi- purposed network in the way of the dynamic geodetic network
4D without datum points.
(2) It is necessary to modernize the geodetic control network of
Vietnam according to new trends (GNSS CORS network) to satisfy
multi-purposes: requirements of measurement of basic maps,
navigation and tracking, modern crustal movements, setting up the
national geodetic reference and connect to IGS.
(3) The GNSS CORS network includes 3 tiers with total 79
points: 4 points on IGS participation; 8 point setting up the national
geodetic reference; 11 points serves for research modern crustal
movements, 4 points function navigation and tracking and 79 points
serves for measurement basic maps. A point can satisfy many different
tasks.
(4) The data at 4 points in the national GNSS CORS network
located on 4 plate blocks: North East, North West - North Central,
South Central - South and South Sea are adjusted in the international
coordinate system. The results showed that movements of points on
the plate blocks in Vietnam are uneven. The analysis and calculation
based on the real data prove necessity of build the dynamic coordinate
reference frame in our country.
(5) Coordinates of the national GNSS CORS network will be
published each term to serve for surveying basic maps. If the
difference of coordinates between the new date and the published date
is greater than allowed threshold, coordinates of GNSS CORS points
used will be the later value. The dissertation researched a case and
recommended updated interval of time the new coordinate for the