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Sichuan Network GPS Service Introduction Sichuan Seismological Bureau 2006.8

Sichuan Network Gps

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Page 1: Sichuan Network Gps

Sichuan Network GPS

Service Introduction

Sichuan Seismological Bureau 2006.8

Page 2: Sichuan Network Gps

Review of PositioningReview of Positioning

► Single PointSingle PointUsing only one receiver to Using only one receiver to receive signal (C/A code). receive signal (C/A code). Position information is calculated Position information is calculated independently.independently.Advantage:Advantage:

Distance:Distance: UnlimitedUnlimitedCommunication: No neededCommunication: No needed

Complexity: LOWComplexity: LOWDisadvantage:Disadvantage:

Accuracy: 10M, LOWAccuracy: 10M, LOW

Page 3: Sichuan Network Gps

► Single Base DifferentiationSingle Base DifferentiationOne receiver as base One receiver as base station and another as station and another as rover station. Rover rover station. Rover receives the position receives the position correction data to improve correction data to improve its accuracy.its accuracy.DGPS AND RTKDGPS AND RTKThe accuracy of DGPS is The accuracy of DGPS is 3m(C/A code) or 50cm 3m(C/A code) or 50cm (C/A code + L1). (C/A code + L1). RTK(L1,L2) can reach 3cm RTK(L1,L2) can reach 3cm accuracy.accuracy.

Page 4: Sichuan Network Gps

Note :Need to set up a base station. Note :Need to set up a base station. Need a data link for communication.Need a data link for communication.

Single base differentiation is base on the high correlation of Single base differentiation is base on the high correlation of GPS signal on high correlation of GPS signals in nearby area. GPS signal on high correlation of GPS signals in nearby area. Taking the data link in account, the distance between rover Taking the data link in account, the distance between rover station and base station is less than 15km. station and base station is less than 15km.

Problem:Problem:

Uneven Accuracy—degrade as distance increaseUneven Accuracy—degrade as distance increaseLow reliability—Low reliability—Single reference; No integrity monitoring; Single reference; No integrity monitoring; May import error when setting reference stationMay import error when setting reference station

Frequent resetting base stations.Frequent resetting base stations.

Page 5: Sichuan Network Gps

Network GPSNetwork GPS

As the technology of satellite positioning, wireless As the technology of satellite positioning, wireless communication and computer networks process, in communication and computer networks process, in the 1990s, Network RTK was proposed. In early the 1990s, Network RTK was proposed. In early 2000s, as commercial software of Network RTK being 2000s, as commercial software of Network RTK being developed, Realtime differentiation technology is developed, Realtime differentiation technology is moving rapidly into multi-base Network RTK. The moving rapidly into multi-base Network RTK. The most interested is virtual reference station (VRS) most interested is virtual reference station (VRS)

Page 6: Sichuan Network Gps

Formation:Formation:1 A base station network 1 A base station network

made by more than 2 made by more than 2 running GPS base running GPS base stations.stations.

Number of stations:≥3Number of stations:≥3

Distance:50km—70kmDistance:50km—70km

Page 7: Sichuan Network Gps

FormationFormation22 A control center A control center

running Network RTK running Network RTK system softwaresystem software

Page 8: Sichuan Network Gps

FormationFormation33 Reliable data linkReliable data link

Page 9: Sichuan Network Gps
Page 10: Sichuan Network Gps

AdvantageAdvantage1 Increase working range, improve efficiency1 Increase working range, improve efficiency2 Significantly lower system error and initiation 2 Significantly lower system error and initiation

time, improve accuracytime, improve accuracy3 All users are in the same coordinate system3 All users are in the same coordinate system4 Personal surveying system, no local reference 4 Personal surveying system, no local reference

station neededstation needed

Page 11: Sichuan Network Gps

Introduction to Sichuan Province Introduction to Sichuan Province Network GPS Service SystemNetwork GPS Service System

Page 12: Sichuan Network Gps

Reference Station Reference Station NetworkNetwork

13 Stations13 StationsDistance:Distance: Min 42kmMin 42km Max 132kmMax 132km Avg. 86km Avg. 86km

Page 13: Sichuan Network Gps
Page 14: Sichuan Network Gps

交换机

中国地

震局DDN

Lan1 Lan2

寿

数据分流器

系统主交换机MP9400

三楼通讯机房

泸州

宜宾

乐山

内江

绵阳

数据库

(1)

GPSNet(2)

GPSNet(1)

GPStream 数据库

(2)

SCGNet

系统主交换机

系统主路由器

交换机

八楼数据中心

GPSNet路由器 SCGNet路由器

Internet

网桥卡

Control CenterControl Center

Page 15: Sichuan Network Gps

► Control center and Control center and users communicate users communicate thought Internet and thought Internet and wireless networks. wireless networks.

► For wireless networks, For wireless networks, system support system support GPRS/CDMA/GSMGPRS/CDMA/GSM 。。 ..

► Terminals require Terminals require wireless support wireless support hardware such as hardware such as GPRS/CDMA modules GPRS/CDMA modules and GSM Modemand GSM Modem

Sichuan Province Network GPS Service SystemSichuan Province Network GPS Service System

Page 16: Sichuan Network Gps

►The system RTK service area 4.5 万 km 2, covering

major developed area. RTK accuracy±2.5cm(better than±3.0cm) RTD service area36 万 km2

RTD accuracy ±33cm(better than±50cm)

Page 17: Sichuan Network Gps

► To reach the accuracy 0f ±3cm in Chendu, 44 GPS/Geodesy sites are set in 12km distance grid. 8 GPS/Geodesy sites are set randomly in the area for counter check

► To reach the accuracy of ±5cm in Ya’an, 20 GPS/Geodesy sites are set in 10km distance grid.

► All sites perform a 4-hour GPS static observation and level 2 geodesy observation

GGeodesyeodesy Determination Determination

Page 18: Sichuan Network Gps

成都地区外检验不符值的成都地区外检验不符值的

Max 5.7cmMax 5.7cm 平均差值为平均差值为 2.1cm2.1cm 中误差为中误差为 ±2.5cm±2.5cm 。。

1 0 3 . 5 0 1 0 3 . 7 5 1 0 4 . 0 0 1 0 4 . 2 5 1 0 4 . 5 0 1 0 4 . 7 53 0 . 0 0

3 0 . 2 5

3 0 . 5 0

3 0 . 7 5

3 1 . 0 0

3 1 . 2 5

³ É ¶ ¼ Ê Ð × î Ö Õ Ë Æ ´ ó µ Ø Ë ® × ¼ Ã æ µ È Ö µ Ï ß Í ¼µ ¥ Î » £ º Ã ×

Í ¼3

雅安地区外外检验不符值的

最大值为 6.2cm 平均差值为 2.5cm 中误差为±3.2cm 。

1 0 2 . 8 5 1 0 2 . 9 0 1 0 2 . 9 5 1 0 3 . 0 0 1 0 3 . 0 5 1 0 3 . 1 0 1 0 3 . 1 5 1 0 3 . 2 0 1 0 3 . 2 52 9 . 7 5

2 9 . 8 0

2 9 . 8 5

2 9 . 9 0

2 9 . 9 5

3 0 . 0 0

3 0 . 0 5

3 0 . 1 0

3 0 . 1 5

3 0 . 2 0

3 0 . 2 5

Ñ Å ° ² Ê Ð × î Ö Õ Ë Æ´ ó µ Ø Ë ® × ¼Ã æµ È Ö µ Ï ß Í ¼µ ¥ Î » £ º à ×

Í ¼3

Page 19: Sichuan Network Gps
Page 20: Sichuan Network Gps

System Accuracy Evaluation System Accuracy Evaluation

►Two accuracy evaluationsTwo accuracy evaluations First evaluation after 4 GPS reference sites and First evaluation after 4 GPS reference sites and

control center are constructedcontrol center are constructed Second evaluation done after 12 reference Second evaluation done after 12 reference

stations are networkedstations are networked

Page 21: Sichuan Network Gps

► First evaluation uses RTK accuracy from GPSNet First evaluation uses RTK accuracy from GPSNet systemsystem

►Evaluation contentEvaluation content RTK/RTD accuracy inside the network(20 km RTK/RTD accuracy inside the network(20 km

from border )from border ) Analysis of uniformity of accuracy inside the Analysis of uniformity of accuracy inside the

networknetwork Analysis of distance correlation of accuracy Analysis of distance correlation of accuracy

outside the networkoutside the network

Page 22: Sichuan Network Gps
Page 23: Sichuan Network Gps

Attenuation with distance in N axis (m) Attenuation with distance in E axis (m)

Attenuation with distance in height (m)

Page 24: Sichuan Network Gps

Result of the two evaluationsResult of the two evaluations

By using Sichuan Network GPS Positioning By using Sichuan Network GPS Positioning ServiceService

The RTK accuracyThe RTK accuracy Better than Better than ±2.5cm±2.5cm in horizontal direction and in horizontal direction and

even inside networkeven inside network Attenuate rapidly 50 km outside the networkAttenuate rapidly 50 km outside the network

Page 25: Sichuan Network Gps

Features and ApplicationsFeatures and Applications

Page 26: Sichuan Network Gps

1.Combination of fix stations and 1.Combination of fix stations and portable devices. The system not only portable devices. The system not only monitors active rift in Plain Chendu monitors active rift in Plain Chendu and southern area of Sichuan Province and southern area of Sichuan Province but also helps in scientific but also helps in scientific researches and commercial uses. researches and commercial uses.

Page 27: Sichuan Network Gps

With 86km average-distance With 86km average-distance between reference stations, the between reference stations, the network GPS system still satisfy network GPS system still satisfy the design requirement, which the design requirement, which makes our system the largest makes our system the largest area per station among known area per station among known GPS networks. In this way GPS networks. In this way investment efficiency is achieved.investment efficiency is achieved.

Page 28: Sichuan Network Gps

The network GPS positioning service software The network GPS positioning service software using VRS technology, using VRS technology, VRSNET, VRSNET, has achieve has achieve comparative performance through long term comparative performance through long term parallel test with Trimble GPSNet and Leica parallel test with Trimble GPSNet and Leica Spider.Spider.

During the software development, a lot of During the software development, a lot of researches are done. Such as “Modified model of researches are done. Such as “Modified model of distance correlation”, “Optimized network RTK distance correlation”, “Optimized network RTK arithmeticarithmetic”, “Modeling arithmetic for correcting ”, “Modeling arithmetic for correcting network error” and “Implementing internet real-network error” and “Implementing internet real-time service”.time service”.First VRS service software ever developed in First VRS service software ever developed in China.China.

Page 29: Sichuan Network Gps

Bring forward solutions for evaluating Bring forward solutions for evaluating network GPS positioning service using network GPS positioning service using distribution curve of uniformity of network distribution curve of uniformity of network accuracy and attenuation along the accuracy and attenuation along the distance from the network.distance from the network.

Page 30: Sichuan Network Gps

In Chengdu and Ya’an, geometry is In Chengdu and Ya’an, geometry is determined, making “Using GPS determined, making “Using GPS Technology to obtain real 3D Terrestrial Technology to obtain real 3D Terrestrial Information” a reality.Information” a reality.

Page 31: Sichuan Network Gps

Network GPS user management system is Network GPS user management system is effective and secure. Feasible for effective and secure. Feasible for commercial usage. commercial usage.

Page 32: Sichuan Network Gps

Multiple communication method for Multiple communication method for terminals. Users can select one from terminals. Users can select one from GSM/CDMA/GPRS depending their GSM/CDMA/GPRS depending their requirement and the quality of service in requirement and the quality of service in the area.the area.

Page 33: Sichuan Network Gps

The problem with different data transmit The problem with different data transmit standards is solved. Easy and reliable for standards is solved. Easy and reliable for users with different system.users with different system.

Page 34: Sichuan Network Gps

Balanced Power System is a low cost, high Balanced Power System is a low cost, high reliability power supply for man-free GPS reliability power supply for man-free GPS observation station. It solves the problem observation station. It solves the problem of lighting strike and ripple in the power of lighting strike and ripple in the power line.line.

Page 35: Sichuan Network Gps

Using the observation record, the atmosphere Using the observation record, the atmosphere water vaporwater vapor level can be determined for short- level can be determined for short-time weather forecast. time weather forecast.