national gnss/bds cors services in china · 2. gnss/bds cors service system national gnss/bds cors...

National GNSS/BDS CORS Services

in China

Prof. Yamin Dang Chinese Academy of Surveying & Mapping

E-mail：dangym@casm.ac.cn

Outline

Wide Area CORS Service in China 3

Local Area CORS Service in China 4

GNSS/BDS CORS Service System 2

Reference Frame in China: CGCS 2000 1

1. Reference Frame in China: CGCS 2000

A geocentric coordinate system,

coincides with the IERS ITRS

(International terrestrial

reference system)

The origin is the geocenter (the

whole Earth body, including

oceans and atmosphere)

equator

Z

X

Y

Geocenter

IERS IRM

IERS IRP

Reference ellipsoid

Reference ellipsoid

a =6378137.0 m

GM=3986004.418108m3s-2

J2 = 1.082629832258

=7292115.010-11rad s-1

1. Reference Frame in China: CGCS 2000

The orientation is aligned to ITRF97, at epoch 2000.0

The CGCS2000 frame is constrained by 12 IGS CORS stations

IGS CORS

1. Reference Frame in China: CGCS 2000

Initial realization of the

CGCS2000

• Fist level: CORS network,

including 25 CORS stations

• Second level: National GPS

geodetic network 2000, over 2500

points

• Third level: National astro-

geodetic network , over 50, 000 points

1. Reference Frame in China: CGCS 2000

The extended frame of CGCS2000

• 360 national CORS stations

• Over 1800 provincial CORS stations

• 360 CORS stations were

newly established by the

China modern datum

construction project

• 1800 provincial CORS

stations are utilized

1. Reference Frame in China: CGCS 2000

National basic surveying and mapping

Datum transformation between national and provincial

datum

Hazard monitoring

Scientific research

Public services

China plate model

China crustal motion

monitoring

Public

users

2. GNSS/BDS CORS Service System

Global GNSS CORS Stations

Global GNSS Data Center

Global GNSS Data Analysis

Centers

Users, including scientific researchers, IERS, PPP users, industry users

IGS reference frame and products • Station coordinates and velocities

• Orbit and clock products

• ERP (earth rotation parameter)

• Global ionosphere

• …

Service Network and Websites

Rele

asin

g

2. GNSS/BDS CORS Service System

GBAS (Ground-based Augmentation System)

SBAS (Satellite-Based Augmentation System)

•WAAS (Wide Area Augmentation System, USA)

•EGNOS (European Geostationary Navigation Overlay Service, Europe)

2. GNSS/BDS CORS Service System

National GNSS/BDS CORS

service is GBAS-based and official–

controlled, covering the mainland of

China

Provincial services is RTK(Real

Time Kinematic)–based, covering

most provinces in China

Commercial LBS (Location

Based Service), developed by many

companies

National CORS DC and AC located in

NASG (National Administration of

Surveying, Mapping and

Geoinformation of China)

2. GNSS/BDS CORS Service System

National CORS network

GNSS data center

GNSS analysis center

Users

Service network 通信链路

通信链路

接收机

接收机

接收机

接收机

服务器

计算机

防火墙

基准站网

数据中心

用户系统

GPS卫星系统 北斗卫星系统

通讯卫星

通信

卫星

通信

链路

北斗产品

GNSS data center

CORS network

GNSS

Analysis center

Service network

Service network

Users

3. Wide Area CORS Service in China

410 national CORS stations

• 360 stations from the

China modern datum

construction project

• 50 stations located in

the China sea area

National data

center

Provincial data

center

Provincial data center

Communication

network

3. Wide Area CORS Service in China

Primary DC, located in NGCC

(National Geomatics Center of China,

Beijing)

Backup DC, located in the

Geodetic data processing center,

Xi’an

Managing and storing GNSS/BDS

data from 410 national and over

1800 provincial CORS stations

Releasing and broadcasting the

national wide area CORS service

3. Wide Area CORS Service in China

Located in CASM (Chinese academy

of surveying and mapping)

Data analysis and processing

Producing national wide area CORS

service products, including

Station coordinates and velocities

Orbit and clock products

ERP (earth rotation parameter)

Ionosphere

…

3. Wide Area CORS Service in China

Real-time orbit using over 100 CORS stations

GPS: 2cm, vs. IGS

GLONASS: 4cm, vs. IGS

0

5

10

15

20

25

30

35

G01

G03

G05

G07

G09

G11

G13

G15

G17

G19

G21

G23

G25

G27

G29

G31

0

20

40

60

80

100

R01 R03 R05 R07 R09 R11 R13 R15 R17 R20 R22 R24

mm

mm

3. Wide Area CORS Service in China

Real-time orbit using over 100 CORS stations

BDS, VS. GFZ

GEO: 200cm

BDS IGSO/MEO: 15cm

GALILEO, 15cm, VS. GFZ

0

200

400

600

E11 E12 E19

mm

0

500

1000

1500

2000

2500

C01

C02

C03

C04

C0

5

C06

C07

C08

C09

C10

C11

C12

C14

mm

3. Wide Area CORS Service in China

Real-time orbit (forecasting )

GPS: 5cm, vs. IGS

GLONASS: 8cm, vs. IGS

0

50

100

150

200

G01

G03

G05

G07

G09

G11

G13

G15

G17

G19

G21

G23

G25

G27

G29

G31

0

20

40

60

80

100

120

140

160

R01 R03 R05 R07 R09 R11 R13 R15 R17 R20 R22 R24

mm

mm

3. Wide Area CORS Service in China

Real-time orbit (forecasting )

BDS, VS. GFZ

GEO: 250cm

BDS IGSO/MEO: 25cm

GALILEO, 30cm, VS. GFZ

460

480

500

520

E11 E12 E19

mm

0

1000

2000

3000

C01

C02

C03

C04

C05

C06

C07

C08

C09

C10

C11

C12

C14

mm

3. Wide Area CORS Service in China

Real-time clock

GPS: 0.25 ns, vs. IGS

GLONASS: 0.3 ns, vs. IGS

0

0.2

0.4

0.6

0.8

G01G03G05G08G10G12G14G16G18G20G22G24G27G29G31

ns

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

R01 R03 R05 R07 R09 R11 R13 R15 R17 R20 R22 R24

ns

3. Wide Area CORS Service in China

Real-time clock

BDS, VS. GFZ

GEO: 0.5~4.5ns

BDS IGSO/MEO: 0.2~2.0 ns

GALILEO, 0.6 ns, VS. GFZ

0

0.5

1

1.5

2

2.5

3

C01 C02 C03 C04 C05 C06 C07 C08 C09 C10 C11 C12 C14

ns

0.56

0.58

0.6

0.62

0.64

0.66

E11 E12 E19

ns

3. Wide Area CORS Service in China

Final orbit and clock

Product Orbit (cm) Clock (ns) Delay

Fast

GPS:1.5 GPS:0.25

13 h BDS: MEO/IGSO:12; GEO:300 BDS:0.54

GLONASS: 3.9 GLONASS:0.48

GALILEO:9.7 GALILEO:0.27

Final

GPS:1.2 GPS:0.16

10 day BDS: MEO/IGSO:10; GEO:250 BDS:0.48

GLONASS:3.3 GLONASS:0.39

GALILEO:6.3 GALILEO:0.22

3. Wide Area CORS Service in China

Global ionosphere

Modeling：Spherical Harmonic Functions Model

Resolution: 2 hours, 5 degrees in longitude, 2.5 degrees in latitudes

Precision: 2-8 Tecu, compare with IGS

Global product(UTC 12:00) Global product(UTC 24:00)

3. Wide Area CORS Service in China

Troposphere

Resolution: 2 hour

Precision: 6mm, VS. IGS

RM

S(m

m)

DOY

356-363 days of 2015, 8 CORS stations

3. Wide Area CORS Service in China

ERP(Earth rotation parameter)

PM (pole motion), UTC, UT1-UTC products

Precision:

PM (VS. IGS) mas

DOY

dif

fere

nce

PM Rate(VS. IGS) mas/d

dif

fere

nc

e

LOD(VS. IGS) ms/d

dif

fere

nce

DOY

UT1_UTC(VS. IGS) d

iffe

ren

ce

ms

DOY

DOY

3. Wide Area CORS Service in China

Communication between CORS station and the data center

A private network communication

Communication between the data center and user via:

Internet /GPRS

Radio broadcasting

Websites

…

3. Wide Area CORS Service in China

We developed a software

package, compatible with multi-

platforms including Windows,

Windows mobile and Android

Pseudo-range positioning

precision is better than 2 meters

PPP precision is from

centimeters to decimeters

Software embedded

in Windows mobile

platform

Software platform embedded

in Android platform

3. Wide Area CORS Service in China

Tested in Gan Su province CORS network, 16/11/2015

GPS positioning precision components are 0.08m, 0.07m and 0.12m,

for N, E, U

Station GSSB

1.2

1

0.8

0.6

0.4

0.2

0

-0.2

-0.4

-0.6 98000 10300 10800 11300 11800 12300 12800 98000 10300 10800 113000 11800 12300 12800

1.5

1

0.5

0

-0.5

-1

-1.5

-2

-2.5

98000 10300 10800 113000 11800 12300 12800

0.6

0.4

0.2

0

-0.2

-0.4

-0.6

-0.8

m m

m

N E

U

3. Wide Area CORS Service in China

Hand-hold terminal:

MG858

24/11/2015, 1.5 hours

observation

GPS positioning precision

components are 0.57m, 0.40m

and 1.0m, respectively for N,

E, U

MG858 Test field

0 1000 2000 3000 4000 5000 6000-5

0

5

epoch

dN(m

)

0 1000 2000 3000 4000 5000 6000-1

0

1

epoch

dE(m

)

0 1000 2000 3000 4000 5000 60000

2

4

epoch

ds(m

)

4. Local Area CORS Services in China

CORS stations

System center

(SC)

Users

4. Local Area CORS Services in China

Station to SC

Network Router

Reference

Station n

Reference

Station 3

Reference

Station 2

Reference

Station 1

SC to User

SC User

4. Local Area CORS Services in China

Nowadays, more than

6000 CORS stations

within China’s mainland

In the east coastal of

China, average distance

of the CORS network

reach about 70km

SiChuan CORS (over 100 GNSS/BDS station)

HeBei CORS

4. Local Area CORS Services in China

h

dif

fere

nce

cm

h

dif

fere

nce

cm NE U

CORS

User

N(cm) E(cm) U(cm)

2.15 2.72 6.66

GPS positioning accuracy (RMS)

4. Local Area CORS Services in China

h

dif

fere

nce

cm

h

dif

fere

nce

cm

U

U

NEN

E

CORS

User

N(cm) E(cm) U(cm)

1.72 2.27 10.37

BDS positioning accuracy (RMS)

4. Local Area CORS Services in China

h

dif

fere

nce

cm

h

dif

fere

nce

cm

U

U

NEN

E

CORS

User

N(cm) E(cm) U(cm)

1.38 3.71 4.51

GPS/BDS positioning accuracy (RMS)

4. Local Area CORS Services in China

CORS

Route

N(cm) E(cm) U(cm)

3.06 2.5 5.30

GPS/BDS positioning accuracy (RMS)

Remarks